From powered carriages to modern automobiles, the design of the suspension system has always been to keep the occupants of the motorized vehicle reasonably comfortable and safe, while providing isolation from road noise, bumps, and vibrations. Of course, the main combatants in the quest to satisfy the intended audience of the suspension are the components of a suspension system-namely the springs, shocks, and various linkages (like control arms). As the audience for a production car is the intended target market for that specific vehicle, the automakers do the best job they can to design a suspension for that market. Given the parameters of a "dependent suspension," like the live-axle in the Fourth Gen F-bodies, GM worked to produce a variety of tuned suspensions deemed "cost effective," either for a general audience looking for a smoother ride (such as the V-6 base model) or for enthusiasts looking to maximize the handling characteristics of the car (the 1LE package). After being released to the public, the Fourth Gen F-body has attracted quite a following among enthusiasts for its abilities to excel in various forms of competition, including both road and drag racing. Fortunately for enthusiasts, a seemingly endless assortment of aftermarket equipment is available so that the car can be properly fortified for its intended purpose. To that end, one small start-up company was formed in 1998, and later joined forces with Thunder Racing to fill a market niche for expertise in drag-racing chassis and suspension setups.
According to Brian Jeffery, founder of Madman & Co. Racing-and aptly named "Madman" for his high-energy style-"Our shop serves a wide range of race cars, including specialty built spec series racers such as Pro-Mods. But our reputation has been built up by doing custom suspension work and consulting on drag race-bound F-bodies. Getting F-bodies to hook at the strip and maximize their traction to ultimately lower 60-foot and quarter-mile times provided a market foothold that has allowed us to develop our own hand-built products that take the platform deep into the 8s." Many times, an enthusiast hears about or personally sees Jeffery helping out a customer or enthusiast who is battling suspension issues at a strip. He states, "In a lot of cases, an enthusiast doesn't have the suspension background necessary to know what combination of parts and suspension setup will work in order to get the car to hook up properly at the strip. Generally, only after having thrown the whole gamut of popular bolt-on suspension parts at the car and only marginally getting better will someone finally realize they need help and call to discuss suspension setups and what we offer. In addition to F-body specific parts like the Outlaw torque arm, the most important commodity I can provide is technical advice on what will and will not work in order to get the cars to hook."
With formal training at Jerry Bickel's chassis fabrication school, plus the Roy Hill chassis and crew chief schools, Jeffery has been crafting his trade for a few decades. Past accomplishments include being the "clutch" technician on Roy Hill's '96 IHRA Pro-Stock Championship team, and suspension work on numerous F-bodies, including past and present F-body record holders Joe Overton and Rick Intrau.
Follow along as GMHTP takes you inside the Thunder Racing/Madman & Co. Racing chassis shop, and transforms a 9-second Firebird from a bolt-on car into a purpose-built street and drag racing leviathan. Equipped with a Madman-built twin-turbo LT1, the '96 Trans Am of Ohamar Berry will be baselined in its current state and then equipped with a full Madman suspension. Then it will be subjected to the strip again in order to document the differences in 60-foot times, and, just as importantly, the logic behind each suspension change to dramatically reduce the short times.
In baseline form, the '96 Trans Am put down a 60-ft time of 1.482 en route to an uncorrected pass of 9.94 at 140.65 mph. From a technical perspective, no wheelspin was evident, and the car pulled the wheels about 10 inches in the air, setting them down just before the 60-ft mark. The car did pull to the right on both baseline passes, but in general, was controllable down the track without any wandering or off-center wheel corrections. After the installation of the Madman suspension components and the initial suspension tune, the car promptly pulled down a 1.350 60-ft time. Subsequent chassis tuning further reduced the 60-foot time to an outstanding 1.240, with additional improvements on the horizon. According to Jeffery, "The key to making an F-body hook up is being able to put together a suspension package that will allow the adjustability to optimize the parts combination. Identical cars with the same engine, transmission, chassis, and components react differently, requiring various adjustments in order to optimize the combination. From a technical perspective, the longer the tires can stay planted without wheelspin or -hopping, the better the car will ultimately perform. The number one component to make sure the tires don't unload, spin, or hop is the torque arm. By designing my Outlaw arm as the only torque arm on the market with adjustable mounting locations, I can alter the torque-arm angle so that the instant center can be set up in relation to the ride-height, allowing the car to transfer power properly. By zeroing-in on the instant center of the torque arm, the car should plant and launch effectively. Simply measuring a driveline angle (difference between driveshaft and pinion angle) can lead to pinion angle setups that are inappropriate for the car. If a 2-degree down pinion angle creates a severe U-joint angle, what good is it to set up this theoretical best angle, when all you will do is break parts and go slower. Second, in order for proper application of power, the rearend has to be square to the car. From the factory, the F-body's suspension came with tolerances that allowed up to 1/2 inch of left-to-right and forward-to-back location of the rearend. If the rear isn't exactly centered, the car will pull to the left or right. In this case, the car pulled right, indicating even before we took measurements that the left rear tire was forward of the right rear tire. In order to adjust the center of the rearend, a double-adjustable set of upper and lower control arms and Panhard bar are required. Once the suspension is set up properly, it then becomes a matter of experience to optimize the settings of the dampeners. Drag racing is in itself a different form of racing, which requires parts designed to allow proper weight transfer. Having a fast street car with a good handling package is entirely different than optimizing an F-body for drag racing. Shock absorbers designed to improve handling typically bottom-out shortly after launch, inducing wheelspin or -hop. If the shock can't be adjusted to absorb the energy at launch, even the largest drag slick won't be able to remain planted to the strip."
For enthusiasts looking to maximize the drag-racing abilities of their cars, it would be beneficial to understand and apply the key points that Jeffery makes. Aftermarket manufacturers of F-body suspension components make excellent high-quality parts, but it is the responsibility of the enthusiast to be educated, and choose and set up the parts to meet their suspension goals. Purchasing aftermarket suspension components is expensive-doubly so if you have to purchase parts over again because the part or component wasn't designed to address your specific needs. Short of spending serious money in order to attend formal chassis training, a viable option is to call up Madman & Co. to discuss your current setup. No matter if your budget is large or small, the key is that you get the technical expertise in order to maximize your current setup, or create a plan to systematically take your car to the next level.
Testing of the '96 Trans Am was conducted at State Capitol Dragway in Port Allen, Louisiana. Located 17 miles west of Baton Rouge, the track was rented by Thunder Racing/Madman & Co. specifically for testing related to technical and feature articles for GMHTP. Testing occurred on two separate occasions, with one dedicated to baselining the TA and another as part of a track event to document the differences after the suspension was modified. Unfortunately, during testing of the new suspension, the car broke a driveshaft and damaged the output shaft on the TH350 transmission, ending the day. Subsequent testing ensued after the output shaft on the transmission was replaced and a heavy-duty driveshaft was custom-ordered from PST. While in the transmission to repair any damage caused by the driveshaft failure, all clutches were replaced, and the transmission was built back up to race specs. Unfortunately, on the second pass (with the rebuilt transmission and new driveshaft), the input shaft on the transmission sheared off, ending testing until a new transmission could be sourced. Based on the power being put down, it was determined that a race-built TH400 would be a better choice for long-term durability. A Turbo 400 transmission was sourced and rebuilt to race specs by Tranz King of Baton Rouge, and the car was taken back out for testing. Since the TH350 and TH400 have different gearing in First and Second gears, a comparison of 60-foot times isn't quite apples-to-apples. Suffice it to say that when testing resumed, the 60-foot times dropped to 1.24 with no other changes to the suspension.
Temperature: max 77 degrees, min 73 degrees
Barometric Pressure: max 30.05, min 30.01
Humidity: max 41%, min 37%
Winds: ESE at 8 mph
Notes: QA1 shocks all around. Front set at 2, rear set at 6. Launched off the foot-brake at 4 psi of boost. Mickey Thompson ET Street radials (325/50/15), set at 18 psi. The 'Bird lifted the front end about 10 inches, with a slight right-side pull bias.
Notes: All variables the same, except the car was launched at 6 psi of boost.
New Suspension Testing
Temperature: max 72 degrees, min 70 degrees
Barometric Pressure: max 29.88, min 29.85
Humidity: max 26%, min 24%
Winds: West at 6 mph
Notes: QA1 shocks in front set on 2. Suspension limiters set at 4 inches of travel. AFCO rear shocks set at 10 off of tight on extension, 5 off tight on compression. Two degrees down angle on the torque arm, and 1.8 degrees of up angle on the lower control arms; 2.5 degrees of pinion angle. Rear drag-radial air pressure set at 18 psi, and the car was launched off of the foot-brake at 6 psi of boost. Car lifted the wheels approximately 2 feet, and no pull was evident. After this pass, due to NHRA standards (rollcage certification), all testing for the car had to be done with eighth-mile passes.
Notes: Loosened the extension on the rear AFCO shocks two clicks to hit the tires harder on launch, and raised the rear drag-radials air pressure to 18.5 psi. Raised boost at launch to 8 psi. The car came out about 2 feet, and the driveshaft broke cleanly off at the front yoke. After inspecting the car in the pits, it was determined that the output shaft on the TH350 was damaged, and a replacement output shaft and driveshaft would be required before further testing could resume.
Subsequent TestingNotes: After the transmission was rebuilt and a new driveshaft from PST was bolted in, the car was tested with the same setup as Pass #2 of the new suspension. The car lifted the wheels to the limits of the 4-inch travel limiters, and pulled the front end just past the 60-ft mark. Based on the mph and ET of the eighth-mile pass, the car projected out covering the quarter-mile in approximately 9.2 seconds.
Notes: Loosened the extension on the rear AFCO shocks by one click. Raised the rear drag-radial tire pressures by 1/2 pound to 19 psi. Tightened the front-end limiters by reducing 1 inch, and raised the boost at launch to 10 psi. The car launched better with less overall wheel standing, and had personal bests in both 60-foot and 330-ft ETs. Toward the end of the eighth-mile, the transmission let go, invalidating the ET. After returning to the shop, it was determined that the input shaft on the freshly rebuilt TH350 had sheared off, thus destroying the transmission.