Third-Gens are plentiful in the boneyard but they don't last forever. This GTA was ripe fo
Though junkyard pickin's for muscle-era Pontiacs are almost non-existent these days and Fourth-Gen Birds are a little too new to be relegated to the recyclers, there is still a good supply of Third-Gen Firebirds, T/As, GTAs and Formulas from which to choose. Hobbyist interest and aftermarket support for Third-Gens continues to grow, albeit slowly, as many love these cars for their great value, hearty performance-when properly modified and tuned-and great budget upgrade potential. Although junkyards and specialist recyclers offer up a banquet of excellent parts, how does one know which to harvest and which to let the reaper till back under? To that end, we did a bit of footwork in an effort to provide a sampling of practical upgrades to benefit your project.
The Third-Gens were produced in a variety of guises from 1982 through 1992. During those years, although many details and components were upgraded, the basic body structure remained the same. It's also shared with the Camaro, so parts availability and interchange between the two brands is excellent.
An "Australian 9-bolt" can be easily identified by counting the rear cover bolts and notin
To upgrade your Third-Gen Firebird, many desirable performance, style and comfort features can be harvested from GTAs, which were built from '87 through '92. Although most of these parts were Trans Am options as well, they were standard equipment on the GTAs. Additionally, the fact that GTAs were produced in significant numbers makes the hunting much easier.
Desirable Rear Ends
One of the most effective performance upgrades to a Pontiac with highway gears is swapping to a limited-slip differential with steeper gears. The first order of business is to determine what gear ratio you already have, then you can decide on what you want.
Even the GTAs have the standard 10.5-inch brake rotors and single-piston calipers (right),
GTAs, and the corresponding Chevrolet IROCs, often came with a Borg-Warner "Australian 9-bolt" rear end, which will bolt right into any Third-Gen Firebird. Though the 9-bolt was a bit stronger than the 10-bolt and considered a good upgrade back in the day, there are very few parts available for it today and the 10-bolt can be built stronger. The lack of parts commonality with the 10-bolt means the 9-bolt's gears and limited-slip carrier will not swap into your 10-bolt. So if you desire the 9-bolt rear simply to upgrade the gear ratio from whatever you have, make sure the entire rear is already in good working order. Both 9- and 10-bolt designs are available with different series limited-slip or open (nonlimited-slip) third members and gear ratios, and either will bolt into your Third-Gen.
The steepest ratios are for manual transmissions, which are very rare in a GTA. (It required ordering a 305 in place of the 350.) Most rear ends will have a metal tag-held on by a differential cover bolt-showing the gear ratio. If your tag is missing, you can still quickly determine your gear ratio. (See sidebar.)
As the number value gets higher, the gear ratio allows quicker acceleration, but results in higher engine rpm at any given road speed, when compared to numerically lower gears. For example, a 2.73:1 ratio will provide poorer acceleration off idle, around town and for drag racing, but will provide a higher top speed than a 3.42:1 ratio. Conversely, the 3.42:1 will offer higher rpm at any given road speed for better acceleration, yet reduce top speed when compared to the 2.73:1 ratio.
This photo shows an '87 GTA rear end with disc brakes. These are the smaller pre-'89 10.5-
Many junkyards charge a core fee for rear ends. If you recoup your core fee by trading in your old rear, it's often much cheaper to buy an entire junkyard limited-slip rear with the gearing that you want than to buy a new limited-slip differential and gears for your present rear-end housing and have them set up.
Keep in mind that when changing gear ratios, you need to swap the corresponding speedometer gears inside the transmission to correct the speedo reading, or it will be wildly inaccurate. To get these parts, follow the speedo cable to the transmission and remove the driven gear housing on the side of the trans. The driven gear will come out with it. Then remove the crossmember bolts and unbolt the trans tailshaft housing to remove the speedo drive gear from the tailshaft.
Installed exclusively on Chevrolet IROC Camaros-but also quite effective on any Third-Gen
Give 'Em A Brake
Scoring an entire rear end also provides a great opportunity to upgrade rear drum brakes to discs, or increase the size of your rear disc rotors. The '89-and-up aluminum PBR calipers and 11.655-inch diameter rotors are considered the best (earlier rotors are about 10.5 inches).
Though there is no difference between the drum and disc brake rear-end housings, each rear (9- or 10-bolt) requires different backing plates, brackets and the correct axles for its particular type. As the different caliper designs also require different rotors, axles, and brackets to fit correctly, your best bet is to get the entire assembly, if possible. If upgrading from drums to discs, you will also need the proportioning valve. All rear-brake upgrades require the parking brake cables specific to the new brakes.
Upgrading the critical front brakes using factory parts is tougher, because only the 1LE (factory road-racing package) cars and '89 Turbo Trans Ams used twin-piston calipers on larger 11.86-inch diameter rotors, as opposed to the non-1LE 10.5-inch rotors and single-piston calipers. Unfortunately, the 1LE brakes are a rare find due to low production-only about 3,000 cars total between Firebirds and Camaros were built with this option, primarily Turbo T/As.
Stiffer urethane sway bar bushings were available on performance Third- and Fourth-Gens. T
As performance increases quickly overtax the braking on a Third-Gen car, and "boneyard bolt-on" upgrades are extremely scarce, we looked into other options. The cheapest and most expedient was to upgrade the stock front system to HPS pads, slotted rotors and steel braided brake lines, for an improvement in both stopping power and pedal feel. Another option was to purchase a complete 1LE front brake setup from Hawks Third Gen for about $850, but keep in mind that you will need to drill out your stock spindle bolt holes to the larger size for the 1LE brakes. All of the shops we spoke to offered this as a service with a spindle exchange.
An excellent low-cost brake upgrade option offered by Ed Miller involves buying the more widely available C4 Corvette 12x0.81-inch rear rotors and calipers from a junkyard and adapting them to the Third-Gen spindles for use up front. The 12-inch C4 caliper is essentially a slimmer 1LE caliper (same diameter pistons), so the Firebird's stock master cylinder is properly sized and proportioned to handle it. Paired with the '89-and-later aluminum PBR rear calipers and rotors, they're essentially a full 1LE brake setup, provided you find a decent deal on a serviceable set of rotors and calipers. Any of these options will still require adaptor brackets, hubs, and drilling of the stock spindles, so consult Ed Miller about price and availability of parts to bolt them on.
Third-Gen Firebirds have earned a reputation as great handlers, thanks in large part to Pontiac's WS6 suspension package. Standard on GTAs and Formulas, and optional on Trans Ams, it consists for the most part of a quick-ratio steering box, upgraded front and rear sway bars, stiffer front and rear springs-which lowered the car about 1.5 inches-and higher-rate gas shocks/struts. The icing on the cake is larger 16x8-inch wheels and 245/50x16 Goodyear "Gatorback" tires.
Always bring your calipers when shopping for sway bars, as all are not created equal. On t
This photo shows a WS6 aluminum driveshaft on a non-junkyard car, so it's clean. When it's
Large-for-the-day, 16x8-inch wheels came on many later performance-package cars, such as t
A simple way to identify a prospective "roller 350" is by the steel coolant lines (highlig
A raised "5.7L" or "5.0L" cast into the block behind the driver-side cylinder head (green
Another desirable option that will require some wiring to install on a standard Third-Gen
The N10 dual exhaust y-pipe was available on '89-and-later cars, and is reputed to be wort
Although the tires and shocks will be of little use after 20 years of service, the front and rear sway bars will make substantial improvements in handling, even with otherwise stock Firebird springs. They're also an easy bolt-on, with the correct bushings and end links. With the addition of high-quality shocks, struts and tires, installing the WS6 suspension package will result in an excellent handling budget-based Third-Gen Firebird.
Though further improvements can be made via additional chassis reinforcement, such as subframe connectors and strut tower braces, these were never made by the factory. However, a suspension component that is unique to the Chevrolet IROC-Z-but is also effective on Firebirds-is the steering brace or "Wonder Bar."
It's mounted between the front subframe horns and the front sway bar mounts (see photo). The Wonder Bar improves steering manners and prevents cracks in the subframe at the steering box mounts. The stock Chevrolet part is flimsy and most that we've seen in the junkyard are bent, so consider spending $50-$60 on a sturdier aftermarket version from Top Down Solutions, Hawks or BMR Fabrication.
Another simple upgrade is to swap in urethane sway-bar end-link bushings, found on Third- and Fourth-Gen performance package cars. They are only about $15 a side new, with upgraded hardware from Top Down Solutions, so don't sacrifice any limbs to get them at the junkyard.
GTAs or 1LE cars often come with aluminum driveshafts, which are reported to be worth a few horsepower as they require less energy to spin, and are easy to remove and install.
These seats from a Sunfire needed to be cleaned, but fit when bolted onto the Third-Gen se
Many Third-Gen F-bodies suffer from cracks in the fuel tank filler necks because of their unsupported design. This can cause a gas odor and fuel leakage down the outside of the tank and left-rear quarter-panel. Another common issue is fuel starvation on right turns when cornering hard. If you decide to replace your fuel tank, source one from a '90 or later, as all those F-bodies have baffles in the tanks to reduce the fuel starvation. The '90-and-later tanks still have the filler neck cracking problem, so make sure it's properly sealed and supported before installation.
Any WS6 (16x8-inch) wheels are popular junkyard quarry, but beware, as many 16-inch Trans Am/Formula "Hi Tech" wheels look the same at first glance. However, different years have different dishes, cap designs and rim lip treatments, so mismatches are common. All 16x8 wheels for Third-Gens were built with different offsets for front (zero offset) and rear (16mm positive offset), so try to find a complete set off the same car in the yard, or purchase a matched set from Hawks Third Gen. The 16-inch IROC wheels can also be used and have this same offset, but are a very different style than the Pontiac wheels. Using Chevrolet-specific parts could result in a credibility loss for your Pontiac.
Go Big Or Go Home
If you're planning a performance engine build, a great junkyard score is a 5.7L (350) block, as it is exactly the same price to rebuild as a 5.0L (305) and has substantially more performance potential. The 350s are available in automatic transmission-equipped Third-Gens from '87 on. Although external dimensions are identical to earlier Chevy V-8s, all F-body V-8s changed in 1987 to include center-bolt valve covers, a hydraulic roller cam, a single-piece rear main seal crank, a different pattern flywheel and a revised intake manifold/cylinder head bolt pattern, so few internal parts interchange with the '86-and-earlier engines.
To that end, although the later 350 can be swapped in, it's better if it's done as an entire assembly from intake to pan to minimize problems. For the '87-and-later 305 cars, a "roller 350" bolts in and only needs bigger injectors and a 350 PROM for the computer. Regardless of the engine you swap in, be sure that you have a cam designed for fuel injection if you are running TPI, or tuning will be a nightmare.
Automatic trans-equipped GTAs-and many auto trans IROCs-come with 350s, as do some of the "big" sedans of the era, such as police cars and taxis. The big cars are throttle-body injected instead of Tuned Port. Another excellent source for a junkyard 350 is a mid '90's Vortec truck engine. Though it requires a Vortec-pattern intake-available from Scoggin-Dickey or Edelbrock-to run your TPI, the engine is otherwise a bolt-in. You can also swap the earlier bolt-pattern heads onto the Vortech block, so no other modifications will be necessary. In addition, some Vortec truck blocks are not drilled and tapped for the hydraulic roller cam spider, which can be easily done if you're rebuilding.
To find a 350 engine in an F-body or taxi, first look for the coolant tubes to the oil cooler. The very rare 1LE 5.0L in Camaros and Firebirds also have this cooler, so check to verify a 350 by looking on the driver side near the distributor, behind the cylinder head. The block will have either a "5.0" for the 305, or "5.7" for the 350 (see photo) cast into the block.
The overhead console has a built-in flashlight, although this one's map pocket has been to
Moving on to exhaust matters, on a few missions as an automotive recycler I have spotted the '89-and-later dual-cat y-pipe. Although in GM ratings they are worth 10 extra hp, converting to a dual cat y-pipe can be a hassle, as it requires the later "high-flow" exhaust manifolds and a different after-cat system. With that said, many aftermarket exhaust manufacturers offer better flowing and smog-legal headers, y-pipes and after-cats for these cars. Though power increases may be marginal on a stone stock 305, freeing up the exhaust provides a solid foundation on which to build more power with further mods.
Perhaps the biggest issue relating to the value of these cars is the condition of the interior. Most of the "soft" stuff-such as dashes, seats, armrests and consoles-were lightly constructed and easily damaged, so few arrive at the junkyards in presentable condition. Fortunately, excellent resources, such as Hawks Third Gen or YearOne, supply many OEM used or New Old Stock parts to replace discontinued dealer items. A number of troublesome mechanicals, such as convertible top parts, rear hatch pull-down repair kits, door hinge repair kits and sturdier Wonder Bars have been redesigned by Top Down Solutions for added durability.
Since GM was kind enough to design most of its seats with the same bolt pattern, we sourced a good set of air-adjustable GTA-style seats from a Pontiac Sunbird Turbo convertible for $45. After a thorough cleaning with a rental carpet cleaner upholstery tool and a swap to the F-body seat brackets, all wires and air-pump tubes hooked up perfectly-even the color was correct. Another option that looked good were Sunfire seats, which would also have required cleaning and a bracket swap.
The overhead console is one optional interior piece that is usually in good condition because of its location out of harm's way. Incorporating the dome light, the ball-mount map light, mileage and appointment reminder wheels, a stowing flashlight, and a pocket for cell phones or garage door openers, it's not high on the list of "necessity" options, but it gives the car a more "cockpit-like" feel. Beware, as overhead console designs for coupe and T-top cars are different, and will not interchange. These can be scavenged from Camaros as well, but the little flashlight will say "Camaro" on it instead of "Firebird."
Body DoubleMost front-end parts interchange. Fenders from '85-'92 Firebirds will swap, but remember only Trans Ams have front fender vents (just behind the front wheel). Noses and Aero Package components changed mounting type and location in 1985, and again in 1991, so fenders for those year noses and Aero Packages have holes or slots in different places. The basic stampings are the same, and even the '82-'84 fenders can be used with minor modifications. Keep in mind that noses and Aero Packages have usually suffered a hard life by the time they hit the yards.
The doors will interchange, but they are very difficult to access internally to retrofit with electrics, windows, and locks etc., so get a door that is already loaded with what you need.
A problem with '85-and-later"vented" Trans Am/GTA hoods is that they kink in the middle because the holes for the long vents weaken them. The '82-'84 Trans Am and '87-and-up Formula "power bulge" hood is stronger and fits perfectly on any '82-'92 Bird or T/A.
"Aero Wing" rear spoilers are not only prone to cracking and chunking if exposed to the elements, they are also very heavy. Replacing one with an earlier solid pedestal-style spoiler will save you about 40 pounds, and it will hold up much better than the later foam-over-steel Aero Wing. An aftermarket fiberglass "Aero Wing" is available, which saves weight and is more durable, but it's not cheap.
Another source of goodies for the Third-Gen cars is the recent appearance in the yards of the Fourth-Gens. All rear suspension components will interchange, though the rear end is wider and will require Fourth-Gen offset wheels. The front seats bolt in, and the rear brakes, by employing the correct Third-Gen mounting brackets and parking brake cables, can be swapped in as well.
Up front, the suspension is completely different, as is the bodywork. Installing a Fourth-Gen engine (LT1 or LS1) will require significant modifications but makes for a very nimble, light, and easy to service Third-Gen.
Which Rear Gear Do You Have?
To determine the gear ratio in your current rear end if your tag is missing, get both rear wheels off the ground and put the car in neutral. Turning one wheel by hand, look at the opposite side to see if the wheel is turning in the same direction, which is limited-slip. Look at the opposite wheel and if it's not turning at all, it's open differential. If you have an open differential, you'll need to put one tire on the pavement or have someone/something hold it stationary. For a limited-slip differential, you'll need both tires off the ground.
Mark the tire you'll be turning and the driveshaft (or yoke) to keep track of the rotations. As you turn the wheel once, count the revolutions of the driveshaft, and at TDC. Again with your turning wheel, estimate the percentage of the last rotation that the driveshaft has made. If your driveshaft has made three full rotations and has turned about 20 percent of another rotation, your gear ratio is in the 3.20:1 range. Looking at the chart, we see that our example of an '88 GTA 9-bolt was available with a 3.27:1 performance gear ratio with automatic transmission, an excellent upgrade for a 2.73:1 rear end. T.A.
|Third-Gen Rear Gear Application Chart|
|Years||Model||Trans||Engine||Displ.||Induction||Manual||Man Perf||Auto ||Auto Perf|
|code/type||Std||Option (G92)||Std||Option (G92)|
|'82-'83||TransAm,||M4,||LU5 V-8||5.0L (305)||CrossFire||3.23||N/A||2.93||3.23|
|'82 Only||Firebird,||M4, A3||LG4 V-8||5.0L (305)||4 bbl||2.73||N/A||2.73||N/A|
|Trans Am, Z28,|
|'83-'85||Firebird,||M5, A4||LG4 V-8||5.0L (305)||4 bbl||3.23||3.73||3.08||3.23|
|Trans Am, Z28,|
|'86-'87||Firebird,||M5, A4||LG4 V-8||5.0L (305)||4 bbl||3.23||3.73||2.73||N/A|
|Trans Am, Z28,|
|'83-'85||Trans Am,||M5||L69 V-8||5.0L (305)||4 bbl H.O.||3.73||N/A||3.42||3.73|
|'85 Only||Trans Am,||A4||LB9 V-8||5.0L (305)||TPI||N/A||N/A||3.23||3.42|
|'86-'92||GTA, Trans||A4/M5||LB9 V-8||5.0L (305)||TPI||3.08||3.45*/-90||2.73||3.42/-88|
|'88-'92||Trans Am,||M5, A4||LO3 V-8||5.0L (305)||TBI||3.08||N/A||2.73||N/A|
| ||Formula,|| |
| ||IROC-Z|| |
|'87-'92||GTA, Trans||A4||L98 V-8||5.7L (350)||TPI||N/A||N/A||3.27*/87||3.27*/88,89|
| ||IROC-Z|| || || || || || || || |
|’89 Only||Turbo||A4||LC2 Turbo||3.8L (231)||SFI||N/A||N/A||3.27*||N/A|
|Trans Am (TTA)||V-6||Turbo|
|*Borg-Warner “Australian 9-bolt” rear axle|
The earlier "pedestal" spoiler is sturdier and much lighter than the later polyurethane ov
Although the entire TPI system can be swapped over to a non-TPI car, this is not only complicated, but stock TPI systems are notorious for choking off high-end power, so it's not a cure-all for a weak performer.
We highly recommend www.thirdgen.org as a great resource for a lot of accurate information. Like any Web site available to everyone, though, there can be some less-than-correct opinions at times.
Most importantly, before you soldier off to the nearest junkyard in search of these crusty jewels, make sure you're bolting them onto a solid car. Also remember that these parts are not going to be around forever-this is a finite window of opportunity in which they are available in quantity. I bought my first GTOs in the early '80s for a few hundred dollars, and the junkyards were full of them. Now original GTO or Trans Am performance options are like gold. Does history repeat itself? I'm betting on it.
| ||Firebird/Formula||Trans Am||Total|
|Total Third-Gen Firebird Production||819,760|
|Third-Gen WS6 Sway Bar Applications|
|Year/Model||Option or standard||Diameter Front||Diameter Rear|
|'82-'84 Trans Am||WS6 Option||32mm||21mm|
|'84 15th Anniv. T/A||15th Anniv. Option||32mm||25mm|
|'85 Trans Am||WS6 Option||34mm||25mm|
|'86-'92 Trans Am||WS6 Option||36mm Hollow||24mm|
|'87-'92 GTA/Formula||WS6 standard||36mm Hollow||24mm|
|'89 Turbo TA||WS6 standard||36mm Hollow||24mm|