4. Fourth Generation (1993 - present)


4.1 General Information

Q: What models are/were available?

A: Chevy:

Camaro - base model which comes with a Series II 3800 3.8L V6 engine rated at 200 HP. Prior to 1996, the standard engine was a 3.4L V6 with 160 HP with the 3.8L being an option in mid-1995. A 5-speed manual or 4-speed automatic (4L60E) transmission is available. A performance package (Y87) is also available starting in 1996 which includes a posi rear, rear disc brakes, 3.42 gearing in the A4, exhaust pipes/tips on both sides, and sport steering ratio.

RS - appearance package available starting in 1996 for the base Camaro (V6) only. It includes ground effects and an up-level spoiler. "RS" badges are located on the front fenders and rear passenger bumper.

Z28 - high end model which comes with the 5.7L V8 (LT1) engine rated at 285 HP. Prior to 1996, it was 275 HP, but the a second catalytic converter added 10 more HP. A black roof treatment was standard on all 1993 and 1994 Z28s, and 1995 models and later offered a roof that was the same color as the rest of the body as an option. A 6-speed (Borg-Warner T-56) or 4-speed automatic (4L60E) transmission is available. The suspension and brakes are enhanced for improved handling. Two available Preferred Equipment Groups make the car either moderately or fully loaded. "Z28" badges are located on the front fenders and rear passenger bumper. In 1993, an Indy 500 Pace Car version (with automatic transmission) was made with a black and white paint scheme and mutli-colored paint stripes along each side of the car.

SS - available as an upgrade to the Z28 model starting in late-1995 (as a 1996 model). The package include a functional ram air hood scoop and reworked exhaust manifolds resulting in 305 HP and 335 ft-lbs of torque. An optional freer flowing exhaust system brings HP to 315 and torque to 342 ft-lbs. The stock wheels and tires are replaced with 5-spoke 17" ZR-1 style wheels with 275/40ZR/17 tires. Hurst shifter and Torsen differential were available options. Bilstein shocks, stiffer rate springs/bushings, and a larger front sway bar make up the optional Level-II suspension. The stock spoiler is replaced with sleeker looking one. "SS" badges replace the "Z28" badges on the front fenders and rear passenger bumper. All cars were shipped as stock Z28s to Street Legal Performance (SLP) Engineering where the above modifications were made through 1997. After that, GM made the modifications on its own assembly line.

SS/LT4 - available only in 1997 with all of the standard and optional SS equipment, but the LT1 was replaced by a balanced and blueprinted LT4 engine with 330 HP. Additionally, they got a new stainless steel exhaust system and exhaust manifolds, and a new Bilstein performance suspension set-up. The cars had to be special ordered as 30th Anniversary cars with a 6-speed tranny, and no T-tops or convertible, and they were then sent to SLP for modification. Production was limited to 100 cars.

30th Anniversary - appearance package upgrade available only in 1997. All white exterior (plus white 5-spoke 16" wheels) and two orange stripes (about 6" wide) running from nose to tail. The interior got white leather appointments and houndstooth seating surfaces with 30th Anniversary logos. A '96 Brickyard 400 Pace Car version got teal and gold decals on each door and rear quarter panel. 1000 of 30th Anniverary Z28 cars were sent to SLP for conversion into SS's (with 100 of the 1000 being SS/LT4's).

Convertibles - available on all models starting in 1994. The Z-rated tires are a must in order to avoid a speed governor.

Pontiac:

Firebird - base model which comes with a Series II 3800 3.8L V6 engine rated at 200 HP. Prior to 1996, the standard engine was a 3.4L V6 with 160 HP with the 3.8L being an option in mid-1995. A 5-speed manual or 4-speed automatic (4L60E) transmission is available. A performance package (Y87) is also available starting in 1996 which includes a posi rear, rear disc brakes, 3.42 gearing in the A4, exhaust pipes/tips on both sides, and sport steering ratio.

Formula - high end model which comes with the 5.7L V8 (LT1) engine rated at 285 HP. Prior to 1996, it was 275 HP, but the a second cat converter added 10 more HP. A black roof treatment was standard on all 1993 and 1994 Z28s, and 1995 models and later offered a roof that was the same color as the rest of the body as an option. A 6-speed (Borg-Warner T-56) or 4-speed automatic (4L60E) transmission is available. The suspension and brakes are enhanced for improved handling. Two available option packages make the car either moderately or fully loaded. "Formula" badges are located on the front driver headlamp and rear passenger bumper. 1993 and 1994 car badges also had a "V8", and white cars with the white wheels for those same years got badges on the front-lower part of each door. A performance package (WS6) is also available starting in 1996 which includes a ram air hood and intake, freer flowing exhaust, and upgraded suspension.

Trans Am - same setup as the Formula, but with specific nose (fog lights and air dam), tail (contoured lower valance), and side ground effects. It has same rear spoiler as the Formula, although an "up-level" spoiler is an available option. A performance package (WS6) is also available starting in 1996 which includes a ram air hood and intake, freer flowing exhaust, and upgraded suspension.

Trans Am GT - available only in 1994, same as the regular Trans Am, but with all the options including "up-level" rear spoiler and GS-C tires coming standard on the car. All 1993 Trans Ams had the GT treatment as standard, but they were not referred to as GTs. In 1995 and after, the treatment got broken down into a number of options like on the Formula.

Firehawk - available as an upgrade to the Formula model starting in 1993. The package include a functional ram air hood scoop and reworked exhaust manifolds (starting in 1995) resulting in 305 HP and 335 ft-lbs of torque (300 HP and 325 ft-lbs prior to 1995). An optional freer flowing exhaust system brings HP to 315 and torque to 342 ft-lbs. The stock wheels and tires are replaced with 5-spoke 17" ZR-1 style wheels with 275/40ZR/17 tires. Hurst shifter and floor mats were available options starting in 1995. Bilstein shocks, stiffer rate springs/bushings, and a larger front sway bar make up the optional Level-II suspension which was an available option starting in 1996 along with a Torsen differential, up-level (Trans Am) spoiler, fog lamps, and car cover (all separate options). "Firehawk" badges replace the "Formula" badges on the front fenders and rear bumper. Badges are also added to the front-lower doors. Stickers showing the HP rating were placed on each side of the hood scoop from 1993 to 1995. All cars were shipped as stock Formulas to Street Legal Performance (SLP) Engineering where the above modifications were made through 1997. After that, GM made the modifications on its own assembly line. Production is limited: 1993 = 250, 1994 = 500, 1995 = 1,000, and 1996 = 500. Twelve 1994 Trans Am GTs were shipped to SLP as pilot cars and were equipped with the Firehawk setup, of which two are 25th Anniversary convertibles and three are 25th Anniversary hardtops. Some of these pilot cars also had headers installed bringing them up to 325 HP (although it's more like 340 HP).

Firehawk/LT4- available only in 1997 with all of the standard and optional Firehawk equipment, but the LT1 was replaced by a balanced and blueprinted LT4 engine with 330 HP. Additionally, they got a new stainless steel exhaust and exhaust manifolds, and a new Bilstein performance suspension set-up. The cars had to be special ordered with a 6-speed tranny, and no T-tops or convertible, and they were then sent to SLP for modification. Production was limited to 100 cars.

Comp T/A - available only in 1995 and 1996 as a Trans Am with all of the standard and optional Firehawk equipment. Silver exterior (plus 5-spoke 17" x 9" wheels and BFG P275/40ZR/17 Comp T/A tires) and a gray stripe (about 6" side) running from nose to tail. The floor mats and headrests got Comp T/A logos stitched in to them. Logos were also painted below the Trans Am badges on the doors and on the front driver headlamp. Production was limited to 200 cars (72 in 1995 and 128 in 1996).

25th Anniversary T/A - appearance package upgrade to the Trans Am GT available only in 1994. All white exterior (plus white 5-spoke 16" wheels) and blue stripe (about 6" wide) running from nose to tail. The interior got white leather seats and appointments with 25th Anniversary logos. Logos were also painted below the Trans Am badges on the doors. Production was limited to 2000 cars (1750 coupes and 250 convertibles).

Convertibles - available on all models starting in 1994. The Z-rated tires are a must in order to avoid a speed governor.


Q: What's the difference between the '93s and '94s?

A: Main mechanical differences include: a change from Multi-port to Sequential Fuel Injection (including an upgrade from 22 lb. fuel injectors up to 24 lb. injectors), a change from Speed Density to Mass Air Flow (MAF) Control, the EPROM computer chip became soldered to the main computer board making it no longer removable, the 4 speed automatic (4L60) was upgraded hydraulic controls to electronic controls (4L60E), 6 speeds got a 3.42 rear (up from 3.23 in '93), the first gear ratio of the 6 speed was changed so that the overall ratio in first gear was almost identical for both years, a change from single wire O2 sensors to 3 wire heated ones, the air openings on the exhaust manifolds are in a different place, and a dampner was added to the yoke assembly on the prop shaft (this acutally went into production in the later '93 LT1 cars). Additionally, the '94 Pontiac Formulas and Trans Ams with automatic trannys had a switch added to the center console allowing the selection of "normal" or "performance" mode.


Q: What's the difference between the '94s and '95s?

A: No major changes were made to the '95 cars. GoodYear 245/50 16" RS-A All- Season tires became an available option on the LT1 cars. On the Formulas and Trans Ams, 5-spoke 16" polished aluminum wheels became standard (chrome option is set for next year). On Z28s. the black roof and side mirror treatments can be deleted such that they will be the same color as the body of the car. In mid-year '95, a version of the Buick 3800 3.8L V6 is being offered as an option in the base Camaro and Firebird (estimated at 200 hp). A power antenna was added to the hi-end stereo package and the Pontiac steering wheel was redeisgned (which was actually taken from the Grand Prix). The Trans Am GT (name) was dropped and the wild wing and upgraded stereo/performance options which made up the 94 GTs became an option to add to the base Trans Am. The Formula badges on driver headlamp and rear bumper only said "FORMULA" (whereas they had "FORMULA V8" in the past).

The camshaft, distributor, and drive mechanisms for the distributor and water pump are different. The changes were basically made to improve the distributor by adding a ventilation system that is connected to the air intake. This draws air through the distributor to eliminate moisture buildup in the optical mechanism. With the low distributor mounting, plus the water pump being directly overhead, there was a tendancy for moisture and coolant to seep into the distributor leading to the infamous "optispark" problems. The drive mechanism between the cam, distributor, and water pump was also improved.

California, New York, and Mass. emission options add an extra catalytic converter connected at the end of the driver's side header pipe. This gives an estimated 10 HP extra. But such an increase was not advertised.


Q: What's the difference between the '95s and '96s?

A: Dual catalytic converters became standard on all Z28s, Formulas, and Trans Ams. This raised the advertised HP up to 285 from 275 for all such cars. The oil cooler (KC4) was dropped altogether. Recyclable cooper/lead bearings replace cadmium/lead bearings. Low-resistance ignition wires were designed to improve idle quality and cold-start performance. A redesigned ignition coil has half of the primary inductance as the previous coil allowing the primary current to "pour in" much quicker for much improved output at higher RPMs. Revised pistons used a new positive-twist top ring that improved the piston-to-cylinder seal and reduced blow-by emissions at high speeds. The pushrods were no longer hardened as they were in previous years. The exhaust manifolds got tri-layered stainless steel gaskets for improved durability and reduced leaks. The biggest change was that of the on-board computer. 1996 was the first year of OBD-II ECM technology to better diagnoses engine problems. This was good for reliability, but bad for some modifications in that some heavy modifications to the engine could result in a Service Engine Soon light. OBD-II also required oxygen sensors just before and after the catalytic converter for before and after measurements. Although the ones after the converter really only measure the performance of those before it.

Physically there's not much different. The exhaust tips on the Pontiacs changed from the dual-circles to single oval outlets on each side. The year brought a number of new packages. The Buick 3800 3.8L V6 was the only engine in the base Camaro and Firebird. There was also the return of the Ram-Air Pontiac (originally debuted on the late '60s GTOs). This was part of the WS6 performance package. It's just like the Firehawk except the openings on the hood are a little more forward. The package had a freer-flowing exhaust, tighter suspension (32mm front sway bar, 62 Nm front springs, 23-30 Nm variable-rate rear springs, and new valved shocks), and 17" 5-spoke wheels. HP was rated 305. SLP made the WS6 modifications at their plant after the cars left GM's factory.

Other new options included a remote, factory installed, 12-disc compact disc changer (U1S), content theft alarm requiring keyless entry (UA6), 5-spoke chrome wheels (P05). The base Firebird and Camaro models could get a sport package (Y87) with a posi rear, rear discs, 3.42 gearing in the A4, exhaust pipes/tips on both sides, and sport steering ratio. It required the 235/55 16 inch tires (QBC) though. Interior colors available on all cars were graphite, taupe (tan), and red (leather only). A new exterior color of red-orange metallic replaced medium red. As for the 1LE option, it came with A/C for the first time which was standard on all Z28s and Formulas.


Q: What's the difference between the '96s and '97s?

A: No major mechanical changes. The Chevy's got a moderate facelift in the interior with a new instrument panel and dash more like that of the Pontiac. The Chevy's rear taillights were sectioned differently with the outter half as the brake light (red, of course) and the inner half being split (top and bottom) as the turn signal (amber) and revese light (white). Additional cup holders were integrated with the redesigned console on Chevys and Pontiacs. An auxiliary power outlet was added. The vent and climate controls were all backlit and the instrument cluster was redesigned with new 3-D graphics. The high-end stereo systems were also upgraded. The Ponitacs could get the new 500-watt, 10-speaker Monsoon system and the Chevys could get the new 200- watt, 6-speaker system (plus a 12-disc CD changer was available for each. Daytime running lamps arrived (using the parking/turn signal lights on the Pontiacs due to the pop-up headlamps).

As for colors, bright green metallic replaced teal/aqua and bright purple replaced dark purple. A new dark pewter interior replaced the graphite interior, and the medium gray interior color was revised. Also the wipers were redesigned having a lower profile than previously.

Engines remain the same, but the 3800 in the base Firebird and Camaro get a vibration damper. The automatic became the standard transmission in all cars. A manual had to be specifically ordered (like the automatic used to be). This also meant the price of the automatic was built into the base price of the car and thus owner's opting for the manual tranny didn't get any type of price break.


Q: What's included in the B4C police package?

A: According to "The Genuine Camaro White Book" by Michael Antonick, on a 93 Camaro, the B4C "special service" option included:

The term "performance suspension" refers to the suspension which normally comes on a Z28, as opposed to the suspension which comes on the base non-Z28 Camaro or on the 1LE Z28. One other enticing thing is the package is cheaper than the regular Z28 options in order to give law enforcement and local goverment a break. Good luck trying to order one though. First, you have to find a dealer who will do a fleet order for you. The B4C is a "special services package" that is only orderable under a fleet number. It has no "stated" restrictions in the order book, but currently Chevy will not build one for a non-police department. And that means providing documention indicating delivery to a police station.


Q: What's included in the 1LE performance package??

A: The package required these options (Z28/Formula, respectively):

and it consisted of:

The 1993 1LE cars had the same springs and deCarbon shocks (but with much stiffer valving) as on the stock Z28s and Formulas. Initial 1994 1LE cars received the same set-up, but sometime during model year (between Dec 94 and Mar 95), the 1LEs received stiffer (higher/variable rate) springs and the shock valving was slightly reduced (but still considerably stiffer than the stock deCarbon valving). Due to the stiffer springs and modified valving, the 21mm rear sway bar was dropped in favor of the 19mm bar (which was the same as on the stock Z28s and Formulas). In 1996, the Koni double adjustable shocks became standard on the 1LE cars. Increased cooling on 1995 and after models was accomplished by the addition of an air conditioning radiator baffle even though no AC was available in 1995. Also, after 1995, in order to get the 1LE on the Firebird or Trans Am you had to order the WS6 package.

Here's a list of suspension parts and prices for 1994 models:

   Part No.            Description           Wholsale / List Price
   ---------------------------------------------------------------
   22145653  Left front upper control arm     $109.50    $146.00
   22145654  Right front upper control arm    $109.50    $146.00
   22145389  Left front lower control arm     $111.75    $149.00
   22156436  Right front lower control arm    $111.75    $149.00
   26032907  Front stabilizer bar             $67.37     $89.70
   26039956  Stabilizer bar insulator (2)     $7.20      $10.00
   10262147  Rear axle tie rod                $33.94     $45.25
   10164151  Rear lower control arm (2)       $49.31     $65.75
   10021221  Rear stabilizer bar              $45.94     $61.25
   22124790  Rear shock absorber (2)          $57.75     $77.00
   22132561  Front springs (2)                $80.00     $100+
   22132562  Rear springs (2)                 $80.00     $100+

The Lou Fusz automotive network of dealers have items at the wholesale price.


Q: What's included in the WS6 performance package??

A: The package was available starting in 1996 on Formulas Trans Ams only. Included in the package were:

The intake and exhaust add an 30 extra HP giving WS6 cars a total 305 HP.


Q: What's included in the F1-Camaro/Firebird-GT package?

A: This is a package available through most dealerships. It offers a variety of performance and costmetic parts from the GM Performance Group. The following is a list of the parts for the F1-Camaro (and for the Firebird-GT) and can be ordered for your Z28 or Formula through your dealership:

   Part No.  Description
   -------------------------------------------------------------------------
   12363906  32mm front stab. bar, bushings, link kit, and track bar
   12364002  17"x9"x50mm ZR-1 style wheels with P275/40ZR-17 Comp T/A tires
   12363998  16"x8"x66mm ZR-1 style wheels with P245/50ZR-16 Comp T/A tires
   12363902  6-speed Hurst shifter (leather wrapped shift knob)
   12363925  cat-back performance exhaust (dual single-side outlet)
   12363940  3 piece rear spoiler (primed)
   12363915  4 piece ground effects package (primed)
   12363978  cold air induction packge (1993, for use with MAP)
   12363979  cold air induction packge (1994 and up, for use with MAF)
   12363910  F1 Specialty Vehicle Package - everything above (1993)
   12363911  F1 Specialty Vehicle Package - everything above (1994 and up)
   123638xx  coup floor mats (xx is 94-graphite, 95-gray, 96-beige, 97-neutral)
   123638xx  conv floor mats (xx is 98-graphite, 99-gray, 00-beige, 01-neutral)


Q: What special aftermarket cars were available?

A: In 1996, the Harley Davidson Edition Trans Am was available. Harley took a black Trans Am equipped with the WS6 Ram Air package (without the interior from the the factory) and added leather/fabric seats which are embroidered with the Harley Davidson logo. The car also has Harley Davidson decals on the front quarter panels just behind the tires. Only 40 are known to have been made with most of them being distributed in Southern California.

In 1997, the Lingenfelter Hurst Firebird was available. Lingenfelter took a black Firebird Formula with the WS6 Ram Air package and added a 58mm throttle body, LPE intake manifold, LPE CNC ported LT4 heads with hardened pushrods and guideplates, Competition Cams 1.6:1 roller rocker arms and heavy duty dual valve springs with titanium retainers, aluminum driveshaft, Hurst shifter, shorty headers and Borla cat-back exhaust. Power was set at 350 HP. The exterior has a wide gold stripe running the length of the car with Lingenfelter Hurst/Firebird decals and ground effects package. Inside, the head rests and floor mats we embroidered with logos and the car came with a dash plaque, alarm, and custom car cover. The price tag was $44,458.

In 1997, Dennis and Kyle Mecham, of 2nd and 3rd gen Macho Trans Am fame, came back to of produce a 20th Anniversary MACHO Trans Am. The new Macho T/A was available in three stages: Basic, HO, and SD packages. The Basic package included a Mecham-designed rear wing, new fiberglass hood, and painted on Macho graphics. Power modifications include the same bolt-on parts as the Firehawks (315 HP) and was priced around $30,000. The HO package included the Basic upgrades in addition to a cam and head upgrade, raising power to around 400 HP and was priced around $42,000. The SD package included the Basic and HO upgrades in addition to larger/wider wheels, upgraded brakes, and a bored and stroked engine producing up to 500 HP. A wide choice of options was available for the SD and was priced around $60,000 (depending on options). The Macho T/A's were produced at the same location (Glendale, AZ) as the originals of the late-70's and early 80's, although the name had changed from Mecham Pontiac to Biddulph Pontiac. The first three prototypes of the above packages were built, with up to 20 being built in total.

The Pro-Am III Firebird was done by a company in Chattanooga, TN. The cars are base V6 Firebirds with large "Pro-Am III" lettering on the doors. The stock hood got a fiberglass ram air scoop attached to the top (looking the Firehawk/WS6 hood), but it's not functional. It also got side skirts, a dual outlet muffler, a numbered plaque, two-tone paint, chrome 5-spoke 16" wheels (with the original base tires), and different bumper covers.


Q: Why pay more for the Firehawk/SS option than a supercharger would cost?

A: If your only goal is to go fast, don't buy a Firehawk; get a crotch rocket, 454 Vega, or any number of fast vehicles. Different people have different priorities. To some, the Firehawk package offers the perfect balance of performance, good looks, ability to hold its value in the long term, FULL warranty, and price. The same goes for the SS.



4.2 Engine/Induction/Exhaust

Q: What's the difference between the LT1 and its predecessor the L98?

A: There is a recent SAE paper that compares and contrasts the two engines. It discusses history, cooling, lubrication, breathing, ignition, etc. The name of the paper is "New Generation Small Block V8 Engine," SAE paper 920673, by Anil Kulkarni of GM. It can be obtained from the SAE by calling 412-776-4841.


Q: What's the difference between the F-body LT1 and that in the Corvette?

A: The engines are exactly the same with the exception of the air intake and the exhaust. Also the Corvettes have two knock sensors and 4-bolt mains compared to 1 knock sensor and 2-bolt mains on the F-Bodies, repsectively. The Corvette has a larger/wider air intake box plus a dual muffler/exhaust which accounts for the additional 25hp. The F-Bodies are also supposed to have a redesigned oil pan as the Vette one doesn't fit with the F-body crossmember.


Q: Why don't F-Body LT1s get synthetic oil at the factory like Corvettes do?

A: Some Corvette LT1s do not have a engine oil cooler as the f-body cars do. Since this may cause the Vette LT1 to run somewhat hotter, synthetic oil is used for it's ability to withstand higher temperatures without thermal/ viscosity breakdown. Although, Corvettes with the performance suspension are supposed to have oil coolers.


Q: Which cars got an engine oil cooler?

A: Oil coolers were only available on the 1993 - 1995 models. And even then, the oil cooler did not come standard on F-bodies. You got the oil cooler as part of one of the preferred equipment options on a 6 speed car, or if you ordered an automatic equipped car with the performance rear axle. It also came on any car equipped with the 1LE option package.

So, you would not get the oil cooler on an automatic equipped car which came with 2.73 rear end gearing, and you would not get the oil cooler if you order a 6 speed car and then did not order either the 1LE option package or one of the preferred equipment groups.

You can visually inspect your car for the oil cooler. It's simply a metal tube running from above the oil filter to the radiator (carrying antifreeze for cooling) and then back to engine block. The sticker in the glove box should also have a "KC4" which is the option code for the oil cooler.

Some owners of 1995 Formulas and Trans Ams (which should have the cooler based on having an option above), actually claim they don't. It's not yet known why, since sales literature says they should.


Q: Why has oil coated the underside of my engine and transmission?

A: It's most likely that the seal around your intake manifold is leaking. While it was originally thought to be the intake manifold gasket itself leaking, it's now found to be the sealant being used. The reason is a gasket is only applied to the left and right sides of the manifold while the front and back are sealed with RTV sealant. If the sealant is applied to a surface which isn't clean, the oil will be able seep through. This is why the oil leak is usually found at the rear of the engine (dripping down onto the tranny). It can be easily mistaken for a rear main seal leak. And since the RTV sealant is used on the front of the intake manifold, it's not uncommon to find it leaking there, too. A classic symptom of this intake leak is a rough cold idle. There is a Technical Service Bulletin (#476111) which calls for the replacement of intake gasket with a new and improved one, but that's to deal with a problem of the actual gasket (used on the left and right sides of the intake) laminate burning and causing a foul odor to enter the car through the ventilation system. If you have a 1994 F-Body, you might be able to get your oil leak fixed using this TSB (even though it's for a separate, but closely related problem). Otherwise, you'll have to have the dealer verify the leak which will likely be running black-light dye thorugh the engine. The revised gasket kit is part # 12524653.

Other, less common areas to check for leaks include the oil pan gasket, the oil dipstick tube seal (where it enters into the oil pan), and the timing chain cover seal.


Q: Why has my oil pressure reading suddenly started to drop at higher RPMs?

A: A low pressure reading at higher RPMs can be caused by 3 things: worn rod bearings, the oil pump pickup set too low to oil pan, and debris caught in the pump pickup screen. Have you recently had an intake manifold oil leak on your car fixed (as described in above)? If so, it's probable that excess RTV sealant has broken off and got sucked into the engine where it's now lodged in the pickup screen. This will cause oil starvation at higher RPMs. Go back to the dealer and have them check the pickup screen for any clogs.


Q: What's that foul, burnt smell coming in the vents at stop lights?

A: First be sure you don't have the oil leak problem mentioned above. If not, You may have a problem with oil leaking from the O-ring seal around the tailshaft. It drips onto the Y-pipe and burns off with the odor being sucked into the ventilation system. Reports of replacing the seal (part # 8673526) and bushing (part # 6260048) seem to fix the problem. Check with your dealer as these parts are supposed to have been improved/upgraded.


Q: What air intake (induction) upgrades are available?

A: A number of companies sell replacement air intakes for between $130 and $350. Using of one of these intakes along with a K&N air filter can be good for a 10-20 hp increase. An aftermarket exhaust should be installed in addition to an aftermarket induction system for the best performance gains. Although, nothing says one mod should be done before the other. Here are some companies providing systems:

     Arizona Speed&Marine   602-437-2510
     C&L Performance        205-882-6813
     Callaway               800-231-1121
     Car Pro Motorsports    800-670-8862
     GM Performance Parts   (local dealer)
     Hennessey              703-849-5081
     L.G. Motorsports       214-272-7753
     Lingenfelter           219-724-2552
     K&N Filtercharger      (local shop)
     Paxton/Granatelli      805-987-5555
     Random Technologies    770-978-0264
     Saga Enterprises       909-275-0726

Prices range from $150 to $300 depending on the extent and the quality of replacement parts. Kits like Hennessey are plastic and replace the air box right up to the MAF, while Arizona S&M are chrome replacing the air box up to the MAF as well. Saga is a bolt-on scoop which goes under the front driver-side fender, giving a ram-air effect into the stock set-up. One other alternative is the Tornado Air Management System (800-500-8880) which costs around $70. It's a centrifigal air accelerator that fits into the air intake between the air filter and throttle body. It swirls the air, thereby accelerating it (like ram-air) and smooths the flow reducing turbulence and allowing more air to be available per cubic inch for combustion.


Q: How can I make my own air intake without spending a lot of money?

A: While it may not look like the aftermarket chrome and molded plastic ones available, this is a sure-fire, bang-for-the-buck way to create your own air intake for a significantly smaller amount of cash.

Most of the following items can be bought at your local parts store or speed shop for around $50. The K&N filter is going to be 80% of that cost. You will need to buy a K&N filter (RE-0870) 9 inch conical air filter (or one of similar size and shape), a 2 to 3 foot long and 4 to 4.5 inch wide flexible hose (Mighty Flow brand intake ducting (part# 96074) works very well), two 4 inch clamps, a 1 inch clamp, and a small Fram (or other brand) crankcase filter. If the K&N filter includes its own clamp, then you only need to buy one 4 inch clamp. If you can't find any type of intake ducting hose, you can use flexible hosing like that on your clothes dryer, but this type of hose isn't too rigid and can be easily crushed by the hood. Plus it's difficult to clamp since it's relatively soft.

Installation on the the 1993 cars is going to be a little tricky. Since the 93's are speed density, they don't have a Mass Air Flow (MAF) sensor (like the 94+) which connects your intake hose to the rubber snorkle/elbow going into the throttle body. You'll need to find an INFLEXIBLE piece of tube or hose with the same 4" - 4.5" diameter which you can clamp the intake hose and rubber snorkle/elbow to, thereby connecting the two. A piece of PCV pipe will work. Or you can saw off the end of the stock intake piece (which you are removing), and use that as your connection. The 94's and later make use of the existing MAF sensor, so there's no need to find an extra connecting piece.

On those cars with MAF sensors, use the rubber gasket that's on the stock intake piece (which you are removing) by putting it around the MAF. Then put your new flexible hose onto that. It increases the diameter of the MAF from about 3.5" to about 4" which helps the hose fit nice and snug.

Simply clamp the K&N filter onto the new flexible intake hose and drop it down through the hole that the stock intake piece was sitting in. Then connect the other end of intake hose to the MAF (or your make-shift pipe piece for the 93's). Everything should just lay snuggly in place. The last step is to clamp the small crankcase filter to the air pump hose (whch was originally connected to the stock intake piece). Then you're set to go.


Q: What's that plastic tube which runs perpendicular to the air intake?

A: This is a noise reduction tube which comes with cars with air conditioning. It stores air at heavy throttle as it cuts down on the sucking or howling sound some engines produce. It's not evident whether this interferes with air flow, but it's unlikely. From 1996 and on, all cars had the tube since AC became a standard feature that year. Cars with air conditioning "delete" (option C41), like the '93-'95 1LEs, do not get this tube. The piece without the tube can be ordered from a GM dealer. The '93 - '94 part number is 25147210 and '95 is 25157187.


Q: What aftermarket performance items are available for the V6?

A: As with the LT1s, available modifications include K&N free flow filters, air induction kits from API (800-426-8967), Lingenfelter (219-724-2552), and RK Sport (800-214-8030). Dynomax and Borla exhaust systems are available from RK Sport. You can also get JBA headers, Nitrous Oxide systems, shorter rear gears, low temperature thermostats, computer reprogrammers, underdrive pulleys, and subframe connectors. Motorsports Technologies Inc. (MTI) (404-509-3494) carry most of these mods.


Q: What aftermarket headers are available for the LT1?

A: The following shows the current aftermarket header manufacturers and details on their products:

     Manufact.  Size   Flange  Tubing  Stainless  Coating   Dual-cat avail.
     ----------------------------------------------------------------------
     Ariz S&M   1 3/4   3/8     14ga      No     HPC (ceramic)   Yes
     Edelbrock  1 5/8   5/16    16ga      Yes    Black paint     Yes
     Edelbrock  1 5/8   5/16    17ga      No       Pro-Tech      Yes
     Hooker     1 3/4                     No    High temp black  No
     Hooker     1 5/8                                            No
     JBA        1 5/8   3/8     14ga      No                     Yes
     MAC        1 5/8           16ga      No    High temp coat   No
     SLP        1 3/4                     Yes                    Yes

Note the MAC's high temperature coating covers the exterior and 2" of the interior. The Edelbrocks alternate between 1 1/2 and 1 5/8 on a cylinder by cylinder basis, alternating in the firing order. The JBAs are AR (Anti Reversion) style which start out 1 5/8, then into an AR tube, and come out at 1 3/4. The 1 3/4 Hookers are full-length headers with no O2 sensor bungs, no AIR tubes, with a collector exiting near mid-tail of tranny, and requires a custom y-pipe at tail of tranny to connect to stock exhaust system.


Q: What's the size of the LT1 throttle body and can I use a larger one?

A: A stock throttle body inlet is 48 mm in diameter. The matching inlet on the intake manifold which it's attached to is about 52 mm. Therefore, you can safely buy a 52 mm one (like that from TPIS) and bolt it on in place of the stock one without any other modifications. Anything larger (like the 58 mm job from Lingenfelter) would require the intake manifold to be bored out to handle in the increased volume of air. The larger throttle bodies are not physically larger, they've just been bored out making the opennings larger.

The additional amount of HP from the 52mm throttle body is questionable. Some reports show little or no increase, yet others claim up to 10 more HP. And some air foils (to smooth the flow through the throttle body) claim to get another 5 HP. But even that is questionable. A 58mm throttle body (in conjunction with the bored intake manifold) might provide a larger increase in HP, but once again, results usually vary.


Q: Why and how should I bypass the throttle body coolant lines?

A: A small amount of coolant is pass through the small hoses connecting to the throttle body. The main reason is so that during the winter months, the higher temperature of the coolant will keep the throttle body warmer thereby preventing icing. That's where the problem lies during the other months. By warming up the throttle body, you're warming up all of the air passing into the engine and thus losing some power (since cooler, denser air makes more power). It is also believed that during the hot, summer months, the coolant pass-through works to cool off the throttle body. So you must be careful when bypassing this so as not to lose it's benefits.

To do the bypass, first remove the small hose going into the throttle body on the driver side. You will probably have to remove the rubber intake elbow and black altenator brace. Make sure you have some rags handy to catch any coolant that my drip out. On the passenger side of the throttle body there are three hoses. Remove the lower one (which is very short and has a 90 degree turn to connect to a metal intake manifold hose). You may have to remove the other two hoses along with the sensors to get better access to the clamp. Then pull the disconnected driver side hose over, and connect it to the metal intake manifold hose from which you just disconnected on the passenger side 90 degree-turn hose. Hold onto that 90 degree hose in case you need it in the future.


Q: Why and how should I bypass the EGR valve/line?

A: The EGR re-routes some of the exhaust gases back into the intake/combustion chamber. This is basically done to reduce emissions. Blocking it off will temperature of the intake since the gases fed back through the EGR are very hot. Lower intake temperature produces more power, but the amount of gases that are passed through the EGR is VERY minimal and probably won't result in much (if any) performance gain. The drawback is increased emissions.

If you look at the back of the passenger side of the intake manifold. You will see a tube that runs up to the manifold from the exhaust manifold. Take the tube off, pull it back, and look at it. You will see a two bolt pattern with a hole in the middle. Make some kind of plate to block the hole and guided on the bolt hole. You can make the plate out of any piece of scrap metal (sheet metal is fine). Put the tube back on with the plate in place.


Q: Why and how should I relocate my idle air temperature (IAT) sensor?

A: The stock position of the IAT sensor (in the rubber intake elbow just before the throttle body) causes it to pick up a lot of intake manifold heat. This can be an extra 10 degrees F at highway speeds and 30 degrees F (or more) at idle. This causes the computer to retard the timing (zapping power) and causes the engine to run overly rich (since the MAF thinks there's more air going through it than there really is due to artifically high temperatures). By moving the IAT towards the air filter (away from the hot manifold), the ECM will get a more accurate reading of the actual intake temperature and will properly adjust the timing and fuel/air ratio. There's no need to worry about the air heating up more as it passes beyond the new location of the IAT since at wide open throttle, it takes the air 15/1000 of a second to travel from the air filter into the engine.

First, remove the IAT sensor from the bend in the rubber intake elbow. Then plug up the hole on the elbow with something. The site you relocate the IAT to will depend on what air intake (stock or aftermarket) you have. You want it as close to (if not, right in) the air filter. Snip the sensor wires first, as you can splice in lengths of wire after the sensor is in its new location. On a stock air box, you can drill a hole into the back of the box. On aftermarket intakes, try drilling a hole in the bottom of the air filter itself (works best on K+N conical filters) or on the pipe/tube to which the filter is connected. Either way, make sure the hole is placed in location which sees the air AFTER it passes through the air filter (otherwise debris may ruin the sensor). Then insert the sensor into the hole. After that, just splice wires to reconnect the sensor, solder the connections and protect with electrical tape or heat shrink-wrap.

Note, on ram air Pontiac cars (Firehawk and WS6), the IAT sensor is already located in the intake box. On ram air Chevy cars (SS), it doesn't appear you can relocate the sensor since the intake sits right over the hot intake manifold (which you're trying to get away from).


Q: What temperature is the stock thermostat and can I go lower?

A: Stock on the 4th generation cars is a 180 degree thermostat. This should be good enough for any but the most seriously modified car. Although, you can go down to 170 or even 160. Hypertech sells a 160 which is supposed to be combined with their performance chips/programmers. And contrary to some opinions, the vehicle will not drop out of closed loop with 160 degree thermostat since that depends primarily on O2 sensor temperature, not engine temperature.


Q: What performance "chips/programs" are available?

A: For the 1993 cars, Hypertech, Jet Technologies, Z Industried and Superchips make replacement chips. HP increases vary from 15 up to 30. However, in 1994 and after, chips are soldered into the on-board computer and can't be removed. Hypertech gets around this with their Power Programmer, a hand- held "computer" which plugs into the PCM module under the driver-side dash, and reprograms the stock chip. Performance gains are almost the same as replacing the chip. The programmer costs about $300, considerably more than the $150 - $200 you'd expect to pay for a replacement chip.

The Hypertech Program increases redline and shift points (on auto trannies) by about 500 RPM over stock, and it improves the fuel and timing curves. The cooling fans are enduced to coming on at lower temperatures. Any type of speed limiter will be overridden. It can also adjusting the speedometer for changes to aftermarket gears (like a 3.73). However, it doesn't modify the partial throttle shift points on cars with automatic trannies. Thus, even with the programmer, partial throttle shifts will still occur at higher RPMs than with the stock gearing. But most companies can create a custom chip or program to overcome this.

The Programmer can also be sent back to Hypertech to be reprogrammed to take advantage of modifications like headers, camshafts, and superchargers. One other thing to remember is to run 92+ octane fuel with the chip/programmer. Otherwise the engine is probably going to knock due to the timing change.


Q: Can I keep the stock thermostat after installing a performance chip?

A: Yes, however you should do a little research first. Namely, find out if the new chip modifies the temperature at which the cooling fans come on and off. For instance, the Hypertech chip/program lowers the temperature at which the fans turn on and off. It turns the fans off at approximately 175 degrees F. This will a problem with the stock 180 thermostat because once the engine warms up enough to turn on the fans, the thermostat will cycle to bring the engine temperature down to 180 degrees F and keep it there. This could keep the temperature from getting down to 175 where Hypertech turns off the fans, and the fans could run continuously. This isn't bad for the engine, but it is bad for the fans in that it will probably burn out the fan motors.


Q: Can the fans be rigged to come on while the engine is not running?

A: The following instructions are for all mid-1994 to 1995 production models. Slide two wires into the underhood fuse/relay box in the D2 and J2 slots for the #1 fan relay (D) and #3 fan relay (J). Splice them together and run them through a 1 amp fuse. Hook another wire to the ground. Then, with the ignition on, connect the ground wire to the spliced fan wires and both fans come on at high speed. When you're not using the setup, remove the ground wire and tuck it away so you can't see it. The J2 slot is also connected to the F5 slot in the #3 fan relay, so you can use either one, it seems. This essentially provides the ground signal to the relays just like the PCM would when FAN CNTL A10 and FAN CNTL A11 codes are set in the PCM. The relays click when you make the connection, so everything should be working just like if the computer set both codes.

This set-up requires the ignition to be in the "On" position and requires no splicing/cutting of any stock wiring. This works great to cool off your car at the drag strip especially when the engine is off.

1993 and early-1994 cars don't have dual speed fans and therefore have no #3 (J) fan relay. For these cars you can just round a ground to D2 for the primary fan and F5 for the secondary one.

On 1996 and later models, the wiring has changed and the above procedure will blow the fan fuse and turn on the Service Engine Light. So instead, in the underhood fuse box, remove the relay labeled 'F'. Molded into the plastic on the box itself where the relay was is the letter 'F' as well as numbers for each connector. You want to connect the pin labeled '3' with the pin labeled '4'. Note that this is a real feed, and bypasses the relay, so use at least 14 gauge wire. Current is 12A startup, and 8A running. Use a switch that can handle the load.

Solder the wires to the bottom of the fusebox, and put the switch just in front of the box where there already is a unused hole. Black wires and a black switch makes it looks neat. With this setup, you can turn the fan on whenever you want, even with the engine off. Don't forget to put the relay back once you locate the correct connections. Without relay, a code is set and the Service Engine light is lit. If you happen to get a light, it won't go away until you reset the computer. The easiest way to do that is to disconnect the negative battery cable for about 1 minute.


Q: Why am I losing/smelling antifreeze, but nothing seems to be leaking?

A: Assuming you've checked the radiator cap and main hoses, it's possible your water pump is leaking. There's a small (2 mm) weep hole on the bottom of the pump. Black stains surrounding the hole indicate coolant seepage which is an early warning sign of pump failure. Another indication of a pump leak is if there's green-black staining on the small rubber hose that plugs into the engine block (just behind the main crank belt pulley). Any coolant dripping out tends to drip directly onto the rubber hose where it then flows down to the hot engine block and is boils off (leaving the staining). If you smell coolant at stop lights for instance, it's from it burning off on the block. Since the coolant boils off, the slow leak never has a chance to drip onto the ground, so you'll never see it.


Q: What fuel pressure setting will give me the best performance?

A: Stock settings on the 4th gens are around 43 to 45 psi. The best (adjusted) pressure seems to be variable depending on your cars specific modifications. But even cars with similar mods react differently to pressure adjustments. Some people claim 47 to 49 psi is best, while others find a lower setting like 39 to 42 psi is best. From testing, it seems the computer will adjust itself to a fuel mix level it is comfortable with. So even if you turn up the pressure to 53 psi, after a few wide open throttle runs, the computer will lean out with each successive run, bringing itself down close to levels as though you were running 44 psi. So while adjusting the fuel pressure may have some effect, the computer retains a great deal (not 100%) of control as it will adjust the fuel mix based on each run. So you need to make multiple wide open throttle runs between adjustments of pressure to ensure you get to final equalibrium with the computer. The best way to find what's best for your car is trial and error.


Q: How easy is it to change the spark plugs on the LT1?

A: The easiest way is probably to remove the Y-pipe. Soak all the bolts with WD-40 (best done the night before) and remove them. The Y-pipe and cat should drop right out. Doing this, will give you access to all of the plugs from under the car, except for plug #2. For that one, it's easiest to remove the alternator to get at it from the top.

If you're into doing things the hard way (that is, not removing the Y-pipe), make sure you have a lot of time on your hands and a lot of band-aids for your hands and arms. Before you do anything, realize that the plugs are supposed to be good for up to 100,000 miles, but only time will tell.

Here's the best method (without Y-pipe removal) found so far:

   PLUG  ACCESS  TOOLS REQUIRED       COMMENTS
    1     Top     Socket w/ Swivel     Easy
    3     Top     Socket w/ Swivel     Easy
    5     Bot     Socket w/ Swivel     Slightly tricky
    7     Bot     Socket w/ Swivel     Watch out for O2 sensor
    2     Top     Socket w/ Open End   AC & Exhaust AIR Tubes make it NASTY
    4     Top     Socket w/ Swivel     Completely blind on this one
    6     Bot     Socket w/ Swivel     Difficult to reach, but doable
    8     Bot     Socket w/ Swivel     Skiny arms are a MUST

NOTES:
1. Be sure to replace the heat shield covers on plugs 6, 7, and 8.
2. If you're changing the wires, be sure to route the #7 wire through the the factory heat shield that runs between the exhaust manifold and the block. If it makes contact with the manifold, it's going to burn right through.
3. Use anti-seize compound on new plugs. The factory didn't which made removal that much more difficult.
4. You may want to do the easiest plugs first, (saving #2 for last) to give yourself a sense of accomplishment and to boost your self-confidence.


Q: What spark plugs are available for the LT1?

A: Here's cross reference of the different plugs along with the part numbers: Stock heat range:

Colder range:


Q: Why has my car developed a bad hesitation problem (Optispark)?

A: First, check to your spark plugs wires and make sure none have come off. A few people have already experienced this problem. Then rule out any type of problem with the fuel system (injectors or pump) and air intake (loose clamp or hose). If those are okay, it's most likely your Optispark system. It's the pseudo-distributor of the distributorless LT1 where all the spark plug wires connect into. If water gets in there, it's as good as toast. Definitely head to your dealer to get it replaced as it will start eating your plug and wires in no time if there's something really wrong with it. A hesitation problem due to the Optispark will usually be noticed in certain RPM range. Most commonly, it is in the upper range (3500 - 5000 RPM). But it can certainly develop in the lower or mid ranges as well. You might even get some back-firing. The problem is most common on the 1993 and 1994 LT1s, as in 1995 a vacuum line was added from the intake manifold to the Optispark to draw moisture out of the unit. However, excessive water can cause even 1995 and later cars to develop the problem.


Q: Why does my car have a slight stumble upon slow acceleration?

A: If it usually occurs from idle when then engine is warm and you get a short backfiring just before shifts, then it's probably the coil wire or the coil itself. If you notice the headlights flicker or flash at night when the car stumbles, it's almost assured the coil and/or coil wire need replacement.


Q: Should I use self-aligning or non-self-aligning rockers?

A: You can use either since the LT1 has screw in studs, but non-self-aligning rockers require guideplates. This means longer rocker studs are needed as well as hardened pushrods. And that means more money. But the advantage of the non-self-aligning ones is the reduced valve train noise.


Q: What aftermarket camshafts are available for the LT1?

A: The following shows the current cams and their specs:

     Manufact.   Duration  Lift (1.5)  Lift (1.6)  Lobe  Notes
                 Int  Exh   Int  Exh    Int  Exh   Sep         
     ------------------------------------------------------------------------
     CompCams    210  220   500  510    533  544   114
     CompCams    230  244   510  540    544  576   114   heads, headers
     CompCams    230  242   510  510    544  544   112                   
     CompCams    215  224   500  500    533  533   112   custom grind    
     CompCams    215  224   499  499    532  532   114   2200-5700       
     CompCams    220  230   510  510    544  544   114   2500-6000       
     Crane       198  206   480  480    512  512   112
     Crane       214  220   452  465    481  496   112
     Crane       204  214   429  452    458  482   116
     Crane       208  214   438  452    467  482   112
     Crane       214  222   498  509    520  542   112
     Crane       218  218   498  498    531  531   116
     Crane       215  224   499  499    532  532   112   blower, custom
     Crower      219  227   498  515    531  553   108
     Doug Rippie 222  230   508  528    542  563
     GM                     450  450    480  480         LT1 stock ('93)
     GM          201  208   450  460    480  491         LT1 stock ('94-'95)
     GM          205  207   447  459    477  490   117   LT1 stock ('96)
     GM          203  210   446  449    476  479   115   LT4 stock ('96)
     GM                     474  510    506  544   112   ZZ3*
     GM          218  228   492  492    525  525   112   LT4 HOT
     GM(Crane)   214  224   488  509    521  543   112
     GM(Crane)   222  230   509  528    543  563   112
     GM(Crane)   234  242   539  558    575  595   112
     LG Motors   211  220   500  500    525  525   112   1500-6200
     LG Motors   220  220   500  500    525  525   112   1800-6400
     LG Motors   220  230   480  480    512  512   110   3000-6500
     LG Motors   230  230   480  480    512  512   112   3000-6500
     Lingenfelt  211  219   499  525    530  560   112   1600-5200
     Lingenfelt  213  219   462  471    493  502   112   1600-5200
     Lingenfelt  219  219   525  525    560  560   112   1600-6200
     Lunati      213  218   446  468    475  499   110   1500-5300
     Lunati      215  218   489  503    522  537   113   1500-5500
     Lunati      232  242   510  525    544  560   108   2000-6500
     Lunati      242  252   525  540    560  576   108   2200-6800
     MTI         210  220   500  510    533  544   114
     MTI         230  244   510  540    544  576   112
     TPIS        212  226   483  520    515  555   112   ZZ9 ('93-'94)
     TPIS        212  226   483  520    515  555   112   ZZ9 ('95-'97)

Note the ZZ3 requires a longer camshaft dowel pin for use in 1995 and later LT1s (GM part number 10214485). However, the replacement pin requires that the pilot hole on the cam be drilled slightly larger (in depth and width) to accommodate the larger pin. Note also the hole is tapered at the top and the bottom. That is, at the face of the cam, it's 5/8" across, however, as you go in, the width narrows to 1/2". The depth is 1 5/32", however, the very bottom 3/32" is tapered inwards to a point. So if you have a flat pin, then it will only go in 1 2/32" since the tapered part won't be wide enough to accept the pin any deeper.


Q: What aftermarket camshafts are available for the V6?

A: The following 2.8L engine cams fit the '93-'95 3.4L engine:

     Manufact.       Duration     Lift
                     Int  Exh   Int  Exh
     -----------------------------------
     GM 12363220     204  216   427  454
     GM 12353919     204  214   420  442
     GM 14031378     196  203   394  410
     Crane 254112    198  204   401  403
     Crane 254122    204  214   423  423
     Crane 253901    204  216   427  454
     Crane 253941    216  228   454  480


Q: What's that knocking noise when the engine is cold?

A: While the fuel injectors have a distinct tapping noise (usually under higher throttle), at a light load and low speed there seems to be "piston slap" on some people's cars. This occurs in some of the Vette LT1s as well. There doesn't seem to be anything in the service manuals. Most dealers seem to acknowledge the problem and say it's normal which it seems to be. For some reason, the pistons shrink enough in the cold weather so as to "slap" around a little. Once the car warms up, the noise should go away.


Q: What's that ticking noise when the engine is under load?

A: It might be the EGR tube. It might sound like an exhaust leak from one of manifolds, but check for a possible crack in the EGR tube.



4.3 Tranny/Drivetrain/Rearend

Q: What are the stock tranny gear ratios and torque capacities?

A: The following were available by year:


   Year Model/Optn     1st    2nd    3rd    4th    5th    6th    Final
   ---- -------------  ----   ----   ----   ----   ----   ----   -----
   1993 Manual/M28     3.36   2.07   1.35   1.00   0.80   0.62   2.73 (GU2)
   1993 Manual/M29     2.97   2.07   1.43   1.00   0.80   0.62   3.23 (GU4)
   1993 Auto/MX0       3.06   1.63   1.00   0.70    --     --    2.73 (GU3)
   1993 Auto/MX0       3.06   1.63   1.00   0.70    --     --    3.23 (GU5)
                                                      
   1994 Manual/MN6     2.66   1.78   1.30   1.00   0.74   0.50   3.42 (GU6)
   1994 Auto/MX0       3.06   1.63   1.00   0.70    --     --    2.73 (GU3)
   1994 Auto/MX0       3.06   1.63   1.00   0.70    --     --    3.23 (GU5)

The '95s and later have the same ratios as the '94s. Aside from the CAGS provision and different gearing/input shaft (on the post 93's), all of the 6-speed transmissions are basically the same.

Because of differences in the ratios, the torque capacities are different for each model. The shorter the tranny gear (higher numerically), the less torque it can handle. Note that these ratings from GM can be are considered conservative as they are most likely measured at normal load over 100,000 miles:


   Year Model/Optn Torque Capacity
   ---- ---------- ---------------
   1993 Manual/M28   360 lbs-ft
   1993 Manual/M29   400 lbs-ft
   1993 Auto/MX0     400 lbs-ft
                       
   1994 Manual/MN6   450 lbs-ft
   1994 Auto/MX0     400 lbs-ft

Note that the '95s and later have ratings that are the same as the '94s as nothing changed.


Q: What's the difference between the 4L60 and 4L60E tranny?

A: The 1993 cars came with the 4L60 automatic tranny while the 1994's and later got the electronic version (4L60'E'). The 4L60E got an electronic valve body which can vary the shifts and feel dynamically to meet the existing driving conditions. Acutally, if you drive a '93 and '94 (under normal conditions), there is a noticable difference in that the 93 shifts are much more firm and abrupt. The 94 (and later) have a "variable" feel depending on throttle position, which of course at wide open throttle, feels like the 93. This electronic valving is also supposed to reduce the wear over the life of the tranny. If you have a 93, you might want to try driving in 3rd (or "D" on the Pontiacs). Once the revs get to high in 3rd, put it into 4th (or "OD") manually. Due to the valving, the shifts should be much firmer at all times in 3rd than 4th.


Q: What's CAGS (skip shift) and how does it work?

A: CAGS stands for Computer Assisted Gear Selection and is on 1994 and on cars with 6 speed transmissions. It's purpose is to improve gas mileage and avoid the "gas-guzzler" new car tax. CAGS comes into play under the following conditions:

This will energize the skip-shift solenoid and force a 1st to 4th shift. What happens is you'll be moving happily along when suddenly the "Skip Shift" light goes on in the dash. At this point you will be locked out of 2nd and 3rd. You simply cannot shift into them. At this point several options are available to you:

Interestingly, 1st gear is determined by the PCM calculating from the speed sensor input and the RPM values. Disconnecting the solenoid connector disables CAGS but an error code 84 WILL be set if the PCM does not measure voltage at the solenoid connection to the computer for a period of 26 secs. This code is stored but will NOT light the Service Engine light. Apparently Chevy correctly anticipated the rush for owners to disable this function. A resistor inserted in the connector will allow voltage to the PCM input and prevent this code setting but who cares since the code is reference only.


Q: How do I disable CAGS?

A: There are several electrical connectors going into the transmission. There are three 2-wire connections on the drivers side of the tranny. Two of them are hooked up to large, brass colored protrusions which are solenoids. The third connection is to a small black box on the tailshaft of the tranny. This is the speed sensor (no speedometer cable on the LT1). Disconnecting this will stop CAGS, but your speedo will also not work and the check engine light will come on. Of the other 2 connections, one is up on the tailshaft. This is the reverse lockout solenoid, although it's really a reverse enable solenoid since when it is not powered on, you are locked out of reverse. The final connection is the CAGS solenoid, the farthest forward of the three in the center of the tranny. Unplug it, tape it, and forget it.

The Service Engine light won't come on if you have a 1994 or 1995 car (note, no CAGS on the '93s), but the PCM stores an error code of 84 indicating the open circuit in the CAGS wiring. Since an open circuit (which a disconnected solenoid would be) using 2 wires can only be detected by no current flow, simply insert a resistance relatively close to the DC resistance of the solenoid coil across those wires. That way the current detector will still see the load, assuming the CAGS solenoid is still there and operational. See below for instructions on this.


Q: Why does my Service Engine Light come on now that CAGS is disabled?

A: You most likely have 1996 or later car. In 1996, GM instituted the OBD-II standard on the F-Body computers. This makes modifying the car much more difficult than in the past. Simple changes (such as disabling CAGS) will cause the computer to sense a problem and light up the service engine light. Luckily, you can fool the computer into thinking CAGS is still connected.

The resistance of the CAGS solenoid is 15 ohms. Assuming 13.5 V, that means about 12 W are dissipated. Go to Radio Shack or any local electronics store and pick up a 15 ohms, 10 W resistor (about $0.50). 10 W should should be fine as it will be mounted to the tranny which will work as a heat sink and the skip shift is only active a few seconds at a time, so there won't be much time for any extensive heat build up. But in hotter environments, you might want to use a resistor of 2200 ohms rated at only a 1/4 to 1/2 W.

Simply put the resistor in place of the CAGS solenoid thereby closing the circuit and making the computer think CAGS is still connected. You can also buy some heat shrink tubing to put around the resistor to protect it. Then take a tie wrap and fasten the "eye" of the wire connector to the tranny so everything is nice and tight. The connection be returned to stock form in less than 5 minutes if needed and easily be duplicated again for $1.


Q: How do disable the Skip Shift light as well?

A: The following procedure requires a 10mm socket, extension, ratchet, and awl (or similar tool with a pointed tip):

  1. Disconnect the battery.
  2. Remove the two bolts holding the PCM to the inner fenderwell. (The PCM is the cigar box sized unit located near the passenger side hood hinge.)
  3. Pull the PCM from its lower retaining slot and position the unit so that the connectors are accessible.
  4. To disable CAGS, remove the 32-Way F Micro-Pack connector marked "Blue" on the PCM. There is a red retaining clip that needs to be removed first. (Once the connector is removed you will be able to see a blue connector pin guide.)
  5. Use the awl to open the gray connector back shell (3 snap latches).
  6. Use the awl again to remove the blue connector/pin guide located on the front of the connector (2 snap latches).
  7. Find the white wire in location 15. The pins are marked on the back of the connector where the wires go in to it.
  8. Gently lift the pin retainer for slot 15 while gently pulling the wire from the back of the connector. Once the wire end is clear of the retaining latches, release the pin retainer. Continue to pull the wire until it is free of the connector body. (There is a seal near the back of the connector that will add a little resistance to the pulling.)
  9. Tape off the wire end.
  10. Reinstall the connector/pin guide. (It only goes on one way.)
  11. Snap the back shell in place.
  12. Reinstall the connector on the PCM.
  13. Reinstall the PCM by reversing the first two steps.
  14. Reconnect the battery.

Even though the procedure looks complicated and intimidating, it should only take about 15 minutes to complete. This will cause error code 91 to be set and stored in the PCM in addition to code 84 set by removing the solenoid.

It is interesting to note that on the pre-OBD-II cars with CAGS (1994-1995), instead of disconnecting the CAGS solenoid from under the car (as described in the section above), CAGS can also be disconnected in a similar way to the shift light disconnection. In addition to removing the connector in location 15 of the "Blue" connection on the PCM, also remove the gray connector at location 13 of the "Black" connection on the PCM. This will disable CAGS without having to disconnect anything under the car. However, on the 1996 and later cars, the service engine light will remain lit upon disconnecting connector 13. So the resistor method as described above is recommended for those cars.


Q: Why is there no selectable 1st gear for my automatic tranny?

A: On cars with automatic trannys and the 2.73 rear (GU2) 1st gear can't be selected because in order to pass the Federal noise pollution tests, GM had to lock out selectable 1st gear. It has to do with downshifting into the lowest selectable gear at some speed as the car goes through the sound traps. With the 3.23 rear end, the required speed is high enough that the tranny won't allow a manual downshift all the way to 1st gear. But with the 2.73 gears, the car will downshift all the way to 1st when manually selected thereby increasing engine and exhaust noise. So GM had to prevent 1st gear from being selected on the 2.73 cars in order to meet the guidelines.

However, making 1st gear selectable on these cars is relatively easy. Lift off shifter cover, locate plastic (nylon) stop at the right side of the notched selector ramp, use a hacksaw or X-acto blade to remove the offending (square) stop. Then you will have first gear.


Q: Why does my automatic tranny have trouble going into and out of reverse?

A: While it's normal to take a second or two for the 4L60(E) to shift in and out of reverse, if you find the duration unacceptable or a problem, then check with your dealer on this as there are Technical Service Bulletins for the problem. TSB #4771120A is for 1993 and 1994 automatics where the car has a delay in shifting from park into reverse or drive. Then TSB #677148 is for 1995 and 1996 automatics with delayed gear engagement with reference to the adjustment or replacement of the clutch spacer plate.


Q: What's that screeching noise from my automatic tranny on hard shifts?

A: If you've ruled out that it's the rear tires chirping, then it's most likely belt slippage. This is common on the Corvette LT1s and even some of the later L98 motors. On hard shifts (auto and manual trannys), the shift in the speed of the pulleys will throw the belt and hence the screech of it slipping. It's pretty harmless, although it can be annoying.

You can check with your dealer as there is a Technical Service Bulletin (#476109) which calls for replacement of the belt tensioner with an improved one (part #10238703). Some people have also replaced the A/C pulley, (part #2724717) and the belt (part #12550149).

Others believe the power steering pump pulley to be the culprit. The do-it- yourself solution is to raise the vehicle and support it with jackstands (or ramps). Either look to make sure you have an underhood sticker that shows the routing of the belt or make yourself a picture. Then get under the car and use the appropriate socket and "tighten" the center bolt on the belt tensioner pulley. As you "tighten", the bolt shouldn't move, but the tensioner will swing out, allowing you to pull the belt off with your other hand. Then take an old toothbrush and soak the head in alcohol. Then, for each pulley, spin it with one hand and hold the toothbrush against the surface of the pulley where the belt normally touches. Repeat this until you are pulling back a relatively clean toothbrush on each pulley. Since you can't turn the main crank pulley, just run the toothbrush around it until the pulley is clean. Note that you can accomplish this cleaning with the belt installed and the engine running if you know what you are doing, but this can be EXTREMELY DANGEROUS if you don't have practice and a steady hand because IT IS EXTREMELY EASY TO GET THE TOOTHBRUSH CAUGHT BETWEEN THE BELT AND A PULLEY WHICH COULD CAUSE SERIOUS INJURY. Try the first way to be on the safe side. After the pulleys are clean and the factory belt is off, you can roughen up the PS pump pulley by simply running sandpaper across the PS pump pulley from above. Watch your hands though, because those hoses up there can be HOT. Just scrape the sandpaper across the top of the pulley in a motion from the front to the back of the car. The trick is, you want to roughen the pulley, putting scratches in it in the opposite direction of the belt's travel. Scratch it just enough to dull the surface all the way around. Use a paper towel damp with alcohol to clean off the pulley all the way around where you sanded it to get the grit off. Finally, install a new belt (preferably, Gates K060637, 21mm x 1635mm) and make sure the routing is correct and the belt is centered on each pulley. Lower your car, start it up, and make sure the belt is staying on. Then you can hit the road and open it up, enjoying your quiet shifts (hopefully).


Q: What's that rattling noise from my manual tranny upon acceleration?

A: This is a common problem among 6-speed cars. GM is aware of the problem. The faint but distinct rattling noise can usually be heard with the tranny in neutral and the clutch out. A few quick revs at about 1/8 throttle and it should get louder for a fraction of a second, then disappear, and then return when the engine drops back to idle. You should also be able to hear it when starting out in first from 0-10 mph.

Unfortunately, there's no Technical Service Bulletin or recall to address this problem. But GM does know about it. In 1993 and 1994 cars, the GM Tech Assistant Group (TAN) called for the dealer to replace the clutch with a revised one. Two different part numbers for the revised clutch were found, (12551803 and 12551809), but no one is sure which is correct or if they really exist. 1995 and later cars are supposed to have a revised clutch (part #12551309), however, even people with these cars report to have same rattling noise. As of now, there seems to be no fix for the problem. It's even accepted to be normal by most dealers considering no one has reported any abnormal wear or damage which might be related to the noise.


Q: What is that vibration I feel around 1800-2000 RPM?

A: This problem is an unbalanced driveshaft. Most people with the problem feel it at its worst between speeds of 90 and 120 MPH. Others claim they can also feel it by slowly bringing the RPMs up to the 1800-2000 range with the car in park or neutral. But that isn't necessarily the same problem. Some even start to feel it as low as 60 MPH. It usually starts with a mild resonating vibration you can feel through the gas pedal. Then in at 80 - 90 MPH, the vibration intensified and feels as though it's coming from the center of the car.

It seems cars are coming off the assembly line with the unbalanced drive shafts. A Technical Service Bulletin (#674101) addresses this calling for replacing the stock driveshaft with a 3rd generation all-aluminum driveshaft (part #10085375) which came with the 1LE equipped cars. Although there have also been instances prior to the TSB where it was replaced with the standard 3rd gen steel driveshaft (part #26004464). Either seems to work just fine (although the aluminum one is lighter in weight). Make sure you let your dealer know what the TSB number is as it will be fixed under warranty.


Q: Why does my manual shifter pop out of gear just after going into 2nd?

A: Check with your dealer on this as there is a Technical Service Bulletin (#477202) which is supposed to fix the problem. You may also want to install a Hurst or B-and-M shifter.


Q: What's the best way to install a Hurst shifter?

A: Open the arm rest and remove the 2 nuts in the bottom. Remove the ashtray and disconnect the ashtray light. Remove the shift knob (unscrew it) and remove plastic trim cover. Remove the nut inside the back of the cassette/ CD holder below the radio. Remove nut inside the ashtry well. The center console should be free of the driveshaft hump. There is a light and switch assembly for the arm rest storage. From underneath the console, push up on the switch. Pull it gently through the top. Remove the black retaining clip from the top of the switch. Be careful not to break the tabs on it. Now you can push the light back through the bottom of the arm rest. Fully raise the parking brake. Lift rear of console up and slide the parking brake through the rubber slit. Tilt the console onto the passenger seat. Be careful not to stretch any wires. This should expose the shifter completely.

Remove the shift lever (2 hex nuts on the side). Remove the large rubber boot. This has approximately six small nuts. Remove the four 13mm nuts on the metal housing. Be careful not to strip these. Lift off the old unit (a rectangle metal plate). Put the Hurst unit in its place. Make sure to line up the round bearing with the mate gasket. Put a bead of silicone sealant around the edge of the metal plate. Replace the four nuts with the new ones supplied. Finally re-assemble everthing.


Q: Why was the rearend ratio on the 6-speeds changed from 1993 to 1994?

A: The only reason GM went to the 3.42 rear differential for all the 1994 and later 6-speed models (versus 3.23 in 1993) was to accomodate CAGS. A lower rear gear ratio would bog the engine down too much for a 1st to 4th shift. Note the tranny gears betweeen 1st and 4th were also made much closer mostly due to a taller 1st gear for CAGS. If you combine both the tranny and rear gear ratios, the '93 6-speeds equipped with a 3.23 actually have a higher overall ratio from 1st to 3rd.


Q: What GM rear gears are available for my car?

A: The following will fit the 4th generation f-bodies. However, if you're upgraded from a stock 2.73 rear to above a 3.23 or above, you'll need to upgrade your 2 series carrier to a 3 series carrier. If have a 3.23 or 3.42 stock rear, you can upgrade as up to a 4.10 with the 3 series carrier.


         Ratio      Part number
        --------    -----------
        2.56 : 1     26019802
        2.73 : 1     26043705
        2.93 : 1     26016282
        3.08 : 1     14089176
        3.23 : 1     26046642
        3.42 : 1     26029418
        3.73 : 1     14091497
        4.10 : 1     26016309

The ratio's and part numbers refer to GM's ring and pinion gears.


Q: What's that clunking noise from the rear when decelerating?

A: This noise is most common on cars with an automatic transmission. It usually occurs at downshift points where the rear gears disengage. Some people claim that changing the rear differential fluid and adding the rear diff additive (aka "limited slip oil") fixes this. But in most cases it's a problem with the PCM downshift program. A Technical Service Bulletin (#477124) addresses this in the 1993 - 1994 LT1 powered cars. The TSB describes a "3rd to 2nd downshift clunk" and calls for the computer program to be updated on all 1993 cars and all 1994 Pontiacs with a VIN sequence lower than 239227 and Chevies lower than 194422. All later cars should have the updated program.


Q: What's that whining/grinding noise from the rear on slow turns?

A: The new 4th gens require rearend service (differential oil change) early in life - usually around 7,500 miles (although some have done it even earlier). When you replace the differential oil, make sure you add GM limited slip additive. (Note, the additive should not be necessary if you use synthetic diff oil.) This should alleviate most of the noises coming from rearend. Otherwise, it's probably standard rear gear noise. GM hasn't changed the F-body rear end since 1982 and they all make some form of noise.


Q: Should I use synthetic rearend gear fluid and limited slip additive?

A: As for the rear differential fluid itself, using a good 75W-90 synthetic is the best way to go. As for using the limited slip additive, that all depends on your application. If you primarily use the car for street and strip driving, then use the additive as it will help prolong the life of the rearend and ensure quiet operation of the gears. If you autocross or do any type road racing on a regular basis, then not using the synthetic is will provide better performance in the tight turns, but theoretically, the life of the rearend will be shortened. How much shorter all depends on the type and amount of driving you do.


Q: What does ASR stand for?

A: It's short for "Acceleration Slip Regulator" - more commonly referred to as "Traction Control".



4.4 Suspension/Tires/Brakes

Q: What are the specs on the stock sway bars and springs?

A: The V6 models have a 30mm front sway bar and a 17mm rear sway bar. The spring rates are 223 pounds per inch in the front and 95.4 pounds per inch in the rear.

The regular V8s have a 30mm front sway bar (same as V-6 model) and a 19mm rear sway bar. The springs are 292 pounds per inch up front and 114 pounds per inch in the rear. The 1LE and WS6 suspension package has a 32mm front sway bar and 19mm rear sway bar (note, 1993 and early 1994 1LEs got a 21 mm rear bar). The springs are 360 pounds per inch up front and 130-180 pounds per inch (progressive) in the rear (note, 1993 1LEs got the same springs as regular V8s).


Q: What are the factory front end alignment specs?

A: The settings are:


     Caster      +3 degrees  +/- .5 degree
     Camber      +1 degree   +/- .5 degree
     Toe in     .15 degree   +/- .5 degree 


Q: What are some suggested front end alignment specs?

A: Based on some list member recommendations:


                         Caster           Camber          Toe Total
                          (deg)            (deg)            (in)
                        L      R         L      R
   Stock suspension     +3.5   +3.5      -.5    -.5           0
   Eibach springs       +4     +4        -.8    -.8           0

Q: What's that hallow clunking noise from the rear over bumps?

A: A clunk is most likely the rear springs which are "popping" over bumps. If you have squeak, it's probably caused by the metal springs rubbing against their metal perches. In either case, a Technical Service Bulletin (#B005001) calls for the placement of rubber isolators at the bottom of the springs to act as cushion. You can probably do this yourself by wrapping some rubber hose around the bottom coil (down by the axle) of each spring.


Q: What are the dimensions of the 16 inch wheels?

A: Their size is 16" x 8 ". The offset is 55 mm. Stud attachment circle diameter is 120.7 mm. Stud size is 5-M12 x 1.5 - 6H THD metric.


Q: What tire options are available?

A: All Z28s, Formulas, and Trans Ams come with Good Year Eagle GA (235/55R16) touring tires as stock. Options for Good Year Eagle GS-C (245/50ZR16) tires (option QLC) or Good Year Eagle RS-A (245/50ZR16) tires (option QFZ) are also available. With either of these Z-rated tires, the car gets a the 155 MPH speedometer and does NOT have a speed limiter. This is because GS-Cs and RS-As are Z-rated for speeds over 165 MPH. In 1993 and 1994, only the QLC option was available. In 1995, the QFZ option became available, but it was required for all cars with traction control (ACS). In 1996, QFZ became the "recommended" tire for traction controlled cars, but QLC could be ordered.


Q: How should I rotate my tires?

A: Wheels on the 4th gen f-bodies have the same off-sets on the front as they do on the back. This is unlike some of the 3rd gen cars which have different front and rear wheel offsets. In this case you have to remove the tires from the wheels and move the tires to a different wheel (while keeping the wheels in their respective place). This is not a problem on the 4th gen since all the wheels are exactly the same. You can rotate from front to back (usually every 5,000 miles), but if you have Good Year Eagle GS-Cs make sure you keep the left side on left and the right on the right, since the tires themselves are directional.


Q: How come my GSC tires are showing such excessive wear?

A: That all depends on your driving habits. Obviously, the harder you drive (take-offs, cornering, etc.), the more wear and tear you're going to put on the tires. Be careful though not to gauge the "wear" based on the outer edge of the tire.

Look at a set of new GSCs carefully. The tread depth of the grooves is shallower on about the outer 1.5 inches of tread. There is a very obvious step in the mold at the bottom of the grooves. This is done to make the tread stiffer at the outer edge to improve performance. But a side effect is that the outer edge is going to look worn out before the tires are used up. In fact, they probably have their best performance when that outer 1.5 inches goes bald. This is how Yokahama 008s autocross tires look when they are new.

You should definately replace your GSC tires once you hit the tread wear indicators on the inner two-thirds of the tire. You might also want to get an alignment with a negative camber (around -0.5 to -1.0) to reduce the amount of uneven wearing.


Q: Is it normal for the rear tires to be rubbing against the wheel well?

A: The rear tires on 4th gen f-bodies will rub at the front of the wheelwell under hard cornering. This is caused primarily by the body moving laterally, due to the soft rubber in the panhard bar bushings, with possibly some panhard bar flex as well. It can be lessened by installing poly bushings or an aftermarket bar (which usually comes with harder bushings).

It is conceivable that there might also be some deflection in the rear control arms/bushings which contributes to this. But in any case, the rubbing is cosmetic only, and it shouldn't be damaging the tires.


Q: How much backspacing is required for the wheels?

A: 5 and 3/4 inches.


Q: What is the widest tire I can use?

A: Assuming you've gone to a 17" wheel, 275s should fit without any problems. You should even be able to get away with 285s. As for 315s, they will stick out from under the wheel well, but not excessively. If you have a stock panhard rod, it's likely they will rub in inner wheel well under hard and uneven cornering, possibly resulting in loss of control of the vehicle. But a stiffer panhard rod and jounce bumper spacers (available from SLP), you'll be much safer. The spacers ensure the tire won't hit the outter lip of the fender. If you go to 315, it's suggestable to go with at least a 1/4" offset spacer on each rear wheel (available through SLP). Mr. Gasket also makes wider spacers. Summit carries them in 7/32" and 7/16" sizes (part number 2370 and 2372, respectively) for $20 a pair. You shouldn't need spacers for the front wheels and it's probably not suggestable because of the additional stress the new angle would put on suspension components.


Q: How can I get another locking lug nut key?

A: When you bought your car, you should have received a small, double-business- card-sized piece of paper that had the serial number of the locking lug nut key for your car. Different cars have different keys. Extra keys can be ordered from Amcor (12955 Inkster, Livonia, MI 48150, 800-831-9604). Their hours are 9AM - 11AM and 1PM - 4PM CST. Keys are $10 each and can be shipped overnight.

If you lost the serial number, Amcor will not give you a key. If you're fortunate enough to still have the original key (but no serial number), then you can send your key to Amcor and they might be able to match it up. But make sure you take off the locking lug nuts first just in case you have to remove a tire while Amcor has your key. And, GM does NOT keep a database of keys to cars. If you loose the key and the serial number, the you're out of luck. You'll have to have the locking lug nuts cut off with a power hammer. This will occasionally ruin the lug stud (requiring its replacement), and it could also damage the wheel. But you really don't have a choice considering you lost both the key and the serial number.

It's highly suggested that you write down your serial number in your owners manual or someplace where it won't be lost. It's also suggestable to order an extra key just in case you lose the original.


Q: Why are 1993 front brake pads different from the 1994 and up models?

A: According to the "Parts & Illustrations Manual", the 1994 front caliper housing for the pads was modified thereby requiring thinner pads. Aside from the housing, all other parts (the piston, seal, pins, etc.) are the same. The 1993 housing asssembly has part numbers 18018730 (right) and 18018731 (left) with the front brake pads as #12510027. The part numbers for the 1994 (and up) housings are 18021251 (right) and 18021252 (left) with the front pads as #12370006. Visually, the 1993 housing is rectangular (looking perpendicular to the hub axis) while the 1994 (and up) housing is more trapezoidal. Also note that these part numbers hold true for both the V6 and V8 models, and that there is nothing different about the rear brake assemblies or pads between these years.


Q: What are the best replacement brake pads to use?

A: GM probably make the best stock replacement pads which will last the longest and provide adequate stopping power. However, if you're looking for improved braking ability from pads, your best bet is go with a set of carbon metallic brake pads. Performance Friction (available through Auto Zone) makes some of the best sets of these pads:


       Pad Type     Front part#/cost   Rear part#/cost
       --------     ----------------   ---------------
       Street        6234 / $39.92      4134 / $49.98
       Z-rated       623Z / $95.62      413Z / $90.62
       90-compound   14.4 / $197.65     13.4 / $128.70
       Winston Cup   702F / $300        702R / $300          

The Street pads are the basic replacements and provide marginally better stopping power over the GM pads. The Z-rated pads are street/strip combo and work excellent with minimal fading and dusting. The 90-compound pads are meant for hard race track driving. They dust a lot, but provide the best stopping power short of the Winston Cup pads. For those, you'll have to talk to Dale Earnhardt.


Q: What's that metal squealing noise from the rear on high speed turns?

A: Assuming that you haven't completely run a brake pad down the metal plate, this noise can come from C-clip axle end play. This moves the rotor closer and father away from the caliper mount. When the edge of the rotor touches the caliper mount, you will hear the noise - usually only when turning in one direction (i.e. rotor moves out enough to hit in only one direction). The Caliper mount can be relieved in the area that it touches or the caliper mount can be shimmed. Keep in mind, if this was not a problem, GM would not have shims. In the 1994 service manual, information on this can be found under "Brake Caliper Alignment" in section 4B - page 27 (4B-27), entitled: "Rear axle assembly with rear disc brakes" (figures 1 through 4 and 38). There is however a Technical Service Bulletin (#474201A) for this which you should advise your GM service person about.


Q: Can I bleed ABS brakes without a problem?

A: Yes, although the preferred method is pressure bleeding and using the Tech1 service tool. But you can do a manual bleed if you make sure the ABS system was not active during the last drive. Just start your car and watch the ABS IN-OP light. If it stays on for 3-4 seconds and goes out, all is fine for a manual bleed. If the light stays lit for 10 seconds or more, an error is logged and the Tech 1 tool must scan and clear the code before you bleed. For manual bleeding, make sure you bleed the system in the proper order. There are 2 bleeder points on the ABS unit itself that must be bled first. Then the bleed each brake in order of furtherest from the master cylinder. Rear passenger first, then rear driver, then front passenger, and finally front driver.


Q: What types of higher performance brake fluid are available?

A: Various ones are available and can be safely used:


       Brand            Dry boil     Wet boil     DOT     Price/pint
       -----            --------     --------     ---     ----------
       Prestone HD         ?           284 F       3         $3.00
       Ford               550 F        284 F       3         $3.50
       PFC Z-rated        550 F        284 F       3         $7.00
       Castrol LMA        446 F        311 F       4         $3.00
       ATE Super Blue     536 F        382 F       4        $12.00 (1 liter)
       Wildwood Hitemp    570 F         ?                    $7.00 (3/4 pint)
       AP550             >550 F         ?                   $13.00
       AP600             >572 F         ?                   $21.79
       Castrol SRF        590 F        518 F                $35.50



4.5 Exterior Related

Q: Where can I find 24 inch replacement wiper blades?

A: You can get them from GM, but be prepared to sign loan papers. Otherwise, check at your local Wal-Mart. It's unlikely you'll be able to find just blades which work with the existing frame, but Lexor makes a blade and frame which can replace the stock ones perfectly.


Q: How can I take my wiper arms off?

A: Stop the wipers in the "up" position by turning off the ignition with the wipers on. Mark their positions on the windshield. (Don't turn on the ignition until reinstalling the wiper arms.) Open the hood. For each wiper arm, first pull up the plastic piece covering the base of the arm. It can be raised by pulling out the two tabs that clip it down to the base of the arm. If you want to totally remove it, pull on the cover to disconnect the hinged end. Remove the nut that holds the wiper arm on and pull the wiper arm to its fully raised position (as if you were cleaning the windshield). Wiggle the arm around while applying a little pulling motion and it should come right off.


Q: Can I replace my fixed mast antenna with a retractable one?

A: Yes. The Pontiac part number for the 95's is 100098596 and the Chevy part is 10269281. The list price is $87.33 and the kit includes everything except the harness from the radio to the antenna. You probably should get that harness (part number 12117322) as it will make wiring the antenna easier. You might also try RK Sport (619-433-1663) for their whole kit.

All radios have a provision for switching the relay on the power antenna. You have to run two wires to the antenna from the front of the interior. This will require removing the radio, passenger seat, passenger side kick panel, rear seat cushion, spare tire, and the spare tire cover. The up-down relay power (orange wire) will come from Pin 8 on the back of the radio. You will find Pin 8 in the upper connector of the two piggy-backed connectors at the back of the radio. (The other connector port on the back of the 1995 and on radios is for the remote CD player.) You can purchase a connector lead from any auto store. Get the ones for the micro-pack connectors. Just crimp these connectors to the proper gauge wire and insert them into the connector body. Then plug the connector into the radio. The other wire (red) that you need to run is for the power. You can run this to the unused radio accessory port on the IP fuse panel. Finally, just ground the third antenna lead (black wire) to the antenna bracket.

Installing the power antenna assembly itself is simple, but it does require drilling a hole for the antenna drain. Below the antenna mounting bracket is a flat area that is used for this. Run your hand across this area and you'll find it. Drill a 1/2 to 3/4 inch hole here. Be careful because the rear bumper facia is on the other side. Once the hole is drilled, trim the drain tube, and install it. The factory antenna comes with this attached. You should also purchase the tool for removing the antenna nut located on the outside of the fender. Call Kent-Moore (800-345-2233) for this tool.


Q: What is causing the scatches on my door window?

A: The window alignment needs to be adjusted from inside the door (taking the inside door panel off). There is a Technical Service Bulletin (#651023) which addresses this problem on 1993 - 1995 cars.


Q: What are the plastic blocks under the car that say "Don't Jack Here"?

A: Those blocks are actually spots for jacking up the car, but the label says 'Do not jack here' really means 'Do not jack in front of the plastic block or at the ridge'. If you refer to the Helm manual, one of the drawings indicated that it is one of the proper front jack points.


Q: How can I change my fog light bulb?

A: You should be able to get at them from under the car (on jack stands). First remove the air dam and then pull 3 of the "pop clips" that connect the black plastic piece to the part of the lower front fascia that curves up under the car. This will expose the washer reservoir (opposite the radiator). There are also a couple of screws on each side that need to be removed. Then pull the whole piece out. You can see the wire loom that goes into the back off the fog lights (one per side). Turn these a 1/4 turn (just like pulling a taillight or turn signal light) and they come out. Unclip the old light (be careful not to break any clips) and install the new one. These light bulbs are halogen and will explode if scratched or dropped and they're expensive (about $9.99). Finally, reinstall the bulb, make sure it works, and then put everything back together.

If your fingers are nimble enough, you can replace them from the front. You just need to pry the two pull-retainers on both sides of the fog light out with a small flathead screwdriver. The one closest to the middle of the car will be the hardest to remove and put back in. You will also need to remove the aiming screw and spring. Then the fog light can be removed. A pair of small needle-nose pliers makes re-installation easier.


Q: Why do my headlights flicker when I drop down to 1500 or 1750 RPM?

A: This seems to be from the electric AIR pump turning on and off while the engine is cold. The pump cycles when the engine is cold (hence set very rich by the computer) to add additional air into the exhaust stream for a more complete burn by the catalytic converter(s). The only reason you notice it more at low RPMs is that the alternator works a little harder to adjust to the change in load. It is not a problem. It is the same effect as your house lights getting dim momentarily when you turn on the vaccum cleaner. You will probably see a momentary dimming of the interior lights as well when this happens. You should also see the flicker when you flip the fan switch at idle.


Q: How can I disable my daytime running lights and ambient light sensor?

A: First, gentlty pry off the plastic plate covering the climate controls and stereo. Next, remove the wire cluster(s) from the light and/or convertible top switch (if applicable) so you can get the plastic plate totally out of the way. Then remove the stereo deck with a 7mm socket. You can let it hang and rest on the seat or remove the wire cluster from the back to completely remove it. If you look directly behind where the stereo deck was mounted, you will see a small black box with two wire clusters attatched to the top of it. This is the daytime running light (DRL)/ambient light sensor module. Remove the module from the back of the vent where it's mounted by pulling up and out. Upon inspecting the two wire clusters connected to the module, you will notice one wire cluster on the right is larger and has a black connecting piece, and the one on the left is the smaller wire cluster and has a blue connecting piece. Pull out the smaller wire cluster with the blue connecting piece (you can tape it to the wire or just let it hang). Finally, snap in the module back in place and reasemble your dash board.

It's important not to remove the large wire cluster (black connecting piece) or the whole module itself, as it controls the turn signals as well.


Q: What are those dimples/dents on the top of my rear quarter panels?

A: These seem to be due to the shock absorber mounts. The rear quarter panels are sheet metal (as opposed to the rest of the body which is fiberglass except for the hood). They do not seem to form or worsen over time so it's most likely they came from the factory this way as "birthing marks". They're not very noticable unless you look at an angle. It's right by the antenna on the right panel and in the same location across on the left panel.


Q: Where can I get a Ram Air, Firehawk, or SS hood?

A: Currently, the Firehawk and SS hoods cannot be ordered without a valid VIN of an existing car with documentation of an accident requiring replacement of the hood. But since the WS6 Formulas and Trans Ams aren't considered special production vehicles, it's likely you'll be able to get the Ram Air hood from Pontiac. Your best bet is to go through Craig Clower at Buz Post Motors, Inc. in Arlington, Texas (800-375-7678) who can order the following:


   Part No.      Description           Wholsale / List Price
   ---------------------------------------------------------
   12529226  Ram Air hood               $1131.00   $1508.00
   12529242  Duct-A/CL                  $67.50     $90.00
   12529240  Hose-Pump                  $25.69     $34.25
   12529235  CVR-A/CL                   $125.25    $167.00
   25096933  Air filter                 $19.11     $27.98
   12529823  Cover                      $162.75    $217.00
   14104835  Bolts and screws (4)       $10.20     $13.60
   12529227  Left screen                $54.00     $72.00
   12529228  Right screen               $54.00     $72.00

Total works out to $1649.50 wholesale and $2201.83 list. If Buz Post ships direct to you, you pay list. If it's shipped to a body shop, then the shop is charged wholesale. This is because selling to the general public at body shop prices (wholesale) is forbidden by the powers above. So you might want to work out a deal with a body shop so that they make the $320 markup on the parts and in exchange, paint the hood at a discount (approx $200). However you work it out, look for a total parts, labor, and materials cost of $1500 to $1700. To save some cash, don't pay to have the induction parts installed as it only requires a screw driver and about 20 minutes of your time. If you are mechanically inclined enough open the hood, you can install these parts.

If you have a Camaro or you're looking for a cheaper set up, there are a number of companies which make aftermarket hoods. American Sports Car Design (800-579-0777) makes a "big-block" hood (very similar SLP hood on the SS) which is available for the Firebird or Camaro. Suncoast PGI (888-255-8900) makes a very close WS6/Firehawk-looking hood also available for the Firebird or Camaro.


Q: What aero (dress-up) kits are available for the Camaro?

A: The following companies offer a variety of kits including ground effects (side skirts), hoods, scoops, and spoilers:



4.6 Interior Related

Q: Which cars came with the speed limiter and 115 MPH speedometer?

A: All cars that came with stock touring tires (Good Year Eagle GA 235/55R16) were speed limited to 108 MPH. In addition, they got a 115 MPH speedometer. Cars opting for the QLC package (Good Year Eagle 245/50ZR16 GS-C tires) or the QFZ package (Good Year Eagle 245/50ZR16 RS-A tires, available in 1995 and after), automatically got the 155 MPH speedometer and did NOT have a speed limiter. This is because GS-Cs and RS-As are Z-rated for speeds over 165 MPH. Any car leaving the factory with a Z-rated tires, should also have the 155 MPH speedometer and no speed limiter.


Q: What's "performance mode" button for on some of the Pontiacs?

A: This button was added to 94 Formulas and Trans Ams with automatic trannys. In "normal mode", the transmission gives much smoother shifts and the shift points were done at a lower RPM/MPH. In "performance mode", shift points were raised to higher RPM/MPH and shift were crisp and quick. At wide open throttle (WOT), 1-2 and 2-3 shifts chrips the tires right from under you. Plus little throttle effort was required to force a downshift to get power right up in the 3-4K RPM range. Z28s do not offer this; however, they are always in "performance mode".


Q: Why does my emergency brake always seem to pull up to a different level?

A: This seems to be normal, although you may want to check the emergency brake cable under the car, on the driver's side in the rear, where it splits into two cables. There's a bracket molded into the floorpan that holds the two cables going to each rear wheel. Check to see if the cables are properly guided through the bracket holes rather than outside of them. If they are not properly guided through, then release the emergency brake, and pull on each cable until they slide back into the holes in the bracket.


Q: Why do objects seem to be distorted through the front windshield?

A: This seems to be a problem due to the rake of the windshield and its general form. The distortion isn't noticable on all cars, but it is turning out to be more common than previously thought. Mostly taller and shorter drivers will notice the distortion because the windshield seems to be distorted at the top and at the bottom. You can have it replaced, but there's a good chance the next one will be distorted as well.


Q: What is the Retained Accessory Power feature?

A: This option leaves accessory power 'on' after you turn off the car and remove the key. For 10 minutes you will have power to operate the stereo, power door locks, and power windows. After 10 minutes (or when you open a door) the power shuts off automatically. This is part of the Power Door Lock Option (AU3) which comes with Preferred Equipment Group 2 (FZA2) on the Z28 and Option Packages B (1SB) and C (1SC) on the Formula.


Q: What type of impact will cause the air bags to deploy?

A: A crash at 14 MPH or greater where the point of impact is within 30 degrees of the front of the car.


Q: What's the purpose of the steering wheel recall?

A: This is recall campaign 96-C-27. GM has determined that certain 1995 - 1996 Firebird (as well as 1994 - 1996 Grand Prix and 1995 Trans Sport) vehicles may have been assembled with steering wheel redundant radio control wires pinched between the steering wheel inner foam and the air bag inflator module backing plate. The insulation on the wires may wear away over time, allowing for a short to ground and possibly resulting in the radio controls becoming inoperative and a noise being emitted from the steering column. There is also a remote possibility that the air bag could inadverdently deploy.


Q: Why has my cruise control suddenly stopped working?

A: Check the third brake light. It seems some cars with a blown brake bulb will disable the cruise control system. If this is not the problem, then check with your dealer as there is a Technical Service Bulletin (#569002A) for this which calls for replacement of the cruise control module with an updated one. Apparently, the stepper motor is too sensitive to input from the brake pedal switch causing it not to work at all.


Q: Why does my "ABS In-Op" light come on intermittently?

A: It's possibly a kink in one of the ABS hoses. Locate the hose that goes from the brake vacuum reserve cylinder (the big black "bowl" just above where the steering linkage comes out of the firewall) to the intake manifold. The hose has aluminized heat tape on it where it crosses the head on it's way to the intake manifold. If the hose is kinked, unkink it to restore proper suction to the reserve cylinder. Also inspect for a loose fitting on both ends of the hose. Sometimes this hose has a tendency to kink up in the middle when the the cylinder fitting rotates around towards the engine too much, resulting low vacuum which lights ABS INOP indicator. If the fitting has rotated, push it back towards the fender. If this doesn't fix it, get to the dealer as you may have an electronic or hydraulic ABS problem.

Also, if you just swapped gears, it could be the ABS reluctor gear. Shorter gears (i.e. 3.23) have a wider reluctor than taller gears (i.e. 2.73). If you don't swap in the correct reluctor, then it won't line up with the ABS sensor and the light will come on.


Q: Why does my "Low Trac" light come on intermittently?

A: This light usually comes on as a result of abrupt changes in speed or road conditions. This could be from slamming the brakes or simple changes in road surface where the speed sensors detect some slip or moderation in the speed at one or both of the rear wheels. It's only a problem if the light stays on or comes on very frequently.


Q: Why is my Pontiac cassette radio displaying a weird error code?

A: The radio will detect a number of conditions based on the tape being used, and if there's a problem, one of the following is displayed: "CLN" for clean the heads, "E10" for the cassette being too tight, "E11" for the cassette being broken, and "E13" for communication problems with the unit. Either try cleaning the unit with a cassette cleaner (available at most record and CD stores) or try a different cassette. Also, pressing the "EJECT" button for 5 seconds will clear the "CLN" message. Otherwise have the dealer check it out as there is a Technical Service Bulletin (#649004) which explains all the codes and necessary corrective actions.


Q: What happens if forget the code to my stereo's anti-theft feature?

A: In a word: DON'T! Write it down. Then again, if you're reading this, it's probably too late (i.e. you didn't write it down) and now the stereo is locked. It's probably locked because you either disconnected the battery or removed the stereo. Well you have 8 tries to put in the right code. After the 8 incorrect time, the stereo will display iNOp and you won't be given any more chances. On cars with a "Mute" button on the steering wheel controls, just press it and that will get rid of the iNOp for another 3 tries. If you don't have the mute button to reset it, turn the car (or at least the accessories) on for an hour and the iNOp will go away giving you 3 more tires. Still no luck? Go for another hour and give it another 3 tries. After that and you still don't get it, you're going to have to go to a dealer where they have a factory code to unlock it.


Q: Why is my CD ejected from the radio when I start up my car?

A: This is believed to be related to humidity. No other details are available, but Delco is currently not going to cover any such problems under warranty. Others have said it's related to a low voltage condition at start up where the CD gets ejected to ensure it doesn't get stuck, but there's no proof of this either. However, try turning your key to the "run" (guages light up), but don't start the car. You should hear the fuel pump priming from the rear of car. After 5 second, then turn the key all the way to start the car. If the CD doesn't pop out, you most likely have low voltage at start- up, and by waiting a few of seconds, you give the voltage time to build up.


Q: Is there a CD changer which works with the steering wheel controls?

A: If you have a '95 (or later) Firebird 10 speaker system, then your car is prewired for the Delco 12-disc CD changer and your current radio and steering wheel controls will all work with it. (This is also true of some other non-Camaro '95 GM cars.) The changer's part number is 12343958. If you have a convertible, you will need a short jumper wiring harness. For coupes, the Delco changer fits perfectly on the shelf in the left rear corner. It's a bit tight, but not terribly difficult to install.

The '94 Pontiac radios were intended to control a CD changer, but they didn't get it worked out in time. If you can find a '95 Pontiac 10 speaker radio to install in your '94, you can use it along with wiring harness part #12344015. The '94 steering wheel controls will work fine with the '95 radio.

Speedometer Service in Atlanta sells the 12 disc changer for $409 and the #12344015 harness for $37. Call Hamp at (800) 241-2385 or (404) 998-1666. You can also ask him if he has a '95 radio for your '94 Firebird if you want to go that route.


Q: Can I upgrade my stock Bose stereo system?

A: There are lots of possibilities. If you just want to replace the head unit, AudioLink (800-327-5905) sells wiring harness adaptors for the Bose systems in the new GM vehicles. Pioneer and Clarion make head units that will fit in the stock location.


Q: Can a pre-96 CD holder piece be retrofitted in to the later Camaros?

A: Yes. The 1994-1995 one will fits in the console opening right under the radio. It has slots to hold 8 CDs standing up. The part number is 10247556 and it costs about $4. The holder has Velcro on the bottom, but you need to put an opposing piece on the bottom of the console opening to secure it properly.


Q: Can I run wires from the engine to the interior without drilling a hole?

A: Yes. Remove the ECM (computer) unit (the box with the metal fins) on the passenger side rear of the engine compartment, and swing it out of the way. Directly behind it, on the firewall, is a grommet with a 1.5 inch hole in it. Punch another hole in the grommet, and put your new wire through it. The wire exits inside the car in the corner of the passenger's feet. Take off the side kick panel inside (which includes the molding on the bottom of the door jam) and you can access it.

Q: Where can I drill a hol