Our '01 WS-6 has been on hiatus for a few issues, but we're happy to report that all is well on the Firebird front. Having completed the installation of a homebuilt 383 back in the January 2007 issue ("My First Stroker, Part 4"), we've logged a few thousand miles in this Trans Am without a hiccup. So far, we have been thoroughly enjoying the car's newfound power and sound, and continue to be pleased with its retained driveability. There have even been attempts at traversing the quarter full-bore, but with the stock 10-bolt still out back, adding sticky tires and "going for broke"-literally and figuratively-could be a folly of the expensive-and-dangerous sort.
Fear not, race fans: a tough rear and the obligatory aftereffects (like reactivation of our direct-port nitrous) are on the way. But let's not forget the raison d'tre of this project vehicle-to be a daily-driveable muscle machine-and that translates to a car that's equally at home on the twisties (be it on the Jersey backroads or otherwise) as it is in a straight line. So, while awaiting drivetrain parts that will withstand the test of the strip, why not add some chassis and suspension upgrades that will pay dividends in all areas of performance?
Pontiac did a pretty respectable job on the WS-6 Performance Package, with its specifically tuned suspension upgrades like deCarbon shocks and stiffer antiroll bars. Never looking to mess with success, we've decided to leave the good stuff alone and replace only what we consider true shortcomings in the factory's design. BMR Fabrication is no stranger to the late-model GM performance market, and it offers more than a few performance parts for the beloved Fourth Gen F-body. A pick-through of the company's online catalog revealed just what we were looking for: a bevy of chassis and suspension upgrades that would be equally at home on the street and at the track, be it a dragstrip, road course, or anything in between. After some careful selection, we came up with a set of items we thought would best address factory F-car failings, without going overboard into the oft-traversed realm of "too much is never enough."
The unibody construction of an F-car isn't without its share of flex, and an ideal chassis provides virtually none whatsoever. That's why we grabbed a BMR shock tower brace and a set of subframe connectors to help eliminate it. On a similar note, BMR's Panhard rod relocation kit stiffens the Panhard-rod mounting location, although it is primarily aimed at providing more room for the F-body's much-maligned single-overaxle pipe routing (we were experiencing exhaust rattle that no amount of adjustment seemed to cure). To better keep rear axle movement in check, a set of tubular lower control arms and a Panhard rod were selected, the latter being adjustable to allow precise rearend alignment. Finally, a set of beefier antiroll bars was chosen to reduce body roll on cornering-bars that are reportedly 40 percent stiffer than the popular GM 1LE units. With one exception you'll read about in the captions, all suspension parts include low-deflection, high-durometer polyurethane bushings made especially for BMR, and they only add to the increased rigidity and control that these parts provide.
Check out the install photos for a full review of each of these BMR components. Although some of the items we selected could technically be considered a compromise between street and race needs, that assessment would only be from the perspective of the most extreme race enthusiast (who may have, for example, chosen rod-ended LCAs over bushed ones for his 8-second Z28). Indeed, the beauty of these parts is how well they work in a variety of applications, and this holds true whether we're talking about drag racing, road racing, autocrossing, or just spirited driving on the way home from a hard day at work. While our set of parts represents what we feel offers the best overall performance improvement for our application, we should also note that BMR offers pre-selected "packages" of its own, catering to those in search of vehicle weight savings, high-g handling, or the ultimate in traction at the drags. See the company Web site (www.bmrfabrication.com) for more information.
You'll be pleased to hear that not only do our new BMR parts look sweet hanging under the Trans Am, they have also significantly improved its on-road performance as well. One of the most substantial and immediately noticeable differences is that the car is more composed over road irregularities, like potholes or railroad crossings. This is surely a result of the improved chassis rigidity provided by the BMR subframe connectors, but it's likely just as attributable to our stiffer suspension parts and poly bushings (good riddance, sloppy factory rubber!). Best of all, ride quality has not suffered, which is exactly what we had in mind when we decided to leave our factory springs and shocks alone. Only the occasional one-sided hard hit to the tires causes perhaps a bit more of a jounce than before, and that is likely due to the stiffer antiroll bars transferring more motion to the opposite side of the vehicle.
All in all, the best description is probably that the car is much more taut than it was before, making it feel like a more expensive and refined vehicle. And it still retains excellent ground clearance and ride quality-features that probably would have suffered had we decided to replace more of our factory suspension hardware. We'd probably need a full alignment to make best use of our improved vehicle dynamics, but for now, we're happy with the street and autocross results, and future drag testing should show reduced on-launch wheelhop, too.
We hope we've shown that with some careful parts selection (and a moderate investment of a little more than $1,200), you can improve F-car vehicle dynamics of all types, without compromising daily streetability. "Wolde ye bothe eate your cake, and haue your cake?" In this case, we can answer in the affirmative.