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G-Body Suspension Setup - Star Of The ShowDetroit Speed provides our G-Machine with the ultimate G-body suspension setup From the February, 2012 issue of GM High-Tech Performance By Scott Parker Photography by George D. Rushen
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As we discussed last issue, our mission with the newly acquired '83 T-type is simple: Prove that the aging G-body platform can handle some serious turns. The first step was to pull the rusting body and frame apart, and make sure we had a solid foundation to build. Thankfully Dave Rushen and the students at the Burlington County Institute of Technology had their work cut out for them. Using a host of Summit Racing products, the crew restored our rusty frame and even welded up a few of the problem areas. This meant that it was time to reveal the star of the show, our Detroit Speed Inc suspension. G-Machine moguls Kyle and Stacy Tucker were all too happy to provide Detroit Speed's front and rear Speed Kit. The front kit (PN 031333) is a complete setup of control arms, shocks, springs, chassis braces and an anti-roll bar. Starting with the control arms, Detroit Speed uses Delrin bushings to prevent deflection and give consistent handling. Positive caster (more than factory) is built into the lower control arms as well as heavy-duty sway bar endlinks. The upper arms are particularly trick, using DSE's "Caster Tuner Bushings" to adjust caster without using shims, while also being very precise and permanent. The improved geometry of the design should also help increase static camber (camber gain) and improve roll camber (changed due to body roll). Finite Element Analysis (FEA) was used to model these arms and ensure strength, which lead to CNC machined tube ends and billet ball joint pockets as well as CNC stainless steel cross shafts. Meanwhile, the spring and shock design is quite a bit simpler. The two work in concert with the 1-3/8-inch hollow sway bar to provide a 2-inch drop with optimized rebound, compression, and spring rates. And the chassis braces tie it all together by triangulating the front crossmember and frame rail with 1-1/8-inch x .120-inch wall DOM. With the heavy-duty front-end components ready to dig a sticky set of rubber into the pavement, DSE's rear Speed Kit (PN 043110) would help balance the Buick to induce some "controlled slides." Since the G-body has a traditional four-link style rear suspension, upgrades are fairly simple--upper and lower control arms, sway bar, springs, and shocks. However, that is not to say that designing said parts properly does not require plenty of attention to detail. One of the nicest features of DSE's rear control arms is that they use patented Swivel-Links instead of spherical rod ends, which allow you to run a very sticky tire with no binding and full articulation yet low on noise. Adjustment to pinion angle for improved traction is also very easy. DSE's economical rear shocks, just like the front, provide modern valving technology that will help keep the tires firmly planted. Double adjustable coilovers (front and rear) are also available for greater control, and easy adjustments to ride height. However, our setup used the more traditional style 2-inch drop springs, which come with two urethane jounce bumpers, to interact with DSE's adjustable sway bar. The rear sway bar is available in different thicknesses depending on use and driving style. We went with the larger 1-1/8-inch bar, made out of 520 DOM, that provides 1,084 lb/in or 1,422 lb/in depending on which of the two holes you use. The sway bar mounts to the chassis using more Swivel-Links, as well as the rear end housing, instead of the lower control arms (like factory) to minimize deflection. Just like last time, the DSE components will be installed by the students at the Burlington County Institute of Technology in Medford, New Jersey. Lead by their teachers George D. Rushen, Anthony Mariano and Larry Melrose our G-Machine project is a [rusty] tool for achieving a NATEF certificate and valuable experience for an automotive career. Follow along as the next generation of gearheads overhaul and update the chassis on our '83 T-type project car as we prepare for a life of high-G turns.  1a The students made quick...  1a The students made quick work of the rusty front-end components after removing the wheels.  1b ...Air tools and a few...  1b ...Air tools and a few taps with a mallet helped remove the brake calipers, rotors, tie rods, and control arms. Care has to be taken when removing the lower control arms, so that the spring doesn’t become projectile. A jack is helpful for supporting it and slowly lowering it.  2a The upper control arms...  2a The upper control arms were removed and revealed quite a large section of the frame that had been untreated during our frame resto last time...  2b However, there was still...  2b However, there was still plenty of Summit Racing EVAPO-RUST, Chassis Shield and Spray Paint left.  3 Detroit Speed’s Speed Kit...  3 Detroit Speed’s Speed Kit for the front suspension (PN 031333) covers the shocks, springs, sway bar, upper and lower control arms as well as a chassis brace. The sway bar is 13⁄8-inch (hollow), bent in-house and is made with their front springs and rear setup in mind. While polyurethane is used on the endlinks, the upper and lower control arms use a custom designed Delrin bushing and sleeve combination. The lower arms come with ball joints and steering stops built-in as well as gussets and plenty of cross-bracing. The most trick part of the whole setup, though, is the upper control arms–clearly built by engineers with a penchant for high-G cornering. Improved geometry, with more positive caster, and patented “Caster Tuner Bushings” (that negate alignment shims) make alignments precise and permanent.  4 The new DSE upper control...  4 The new DSE upper control arms replaced the stockers and were bolted to the upper frame rail on the passenger side. All of the control arms required metric 12.9 hardened bolts (instead of the 10.9 originals). Adjustment will be saved for final alignment on BCIT’s state of the art Snap-On camera alignment machine.  5a Repeating the same process...  5a Repeating the same process on the driver side proved difficult as the lower control arm and bushings were fused to the bolts via oxidation....  5b ...A blowtorch helped...  5b ...A blowtorch helped liberate it and then we were on our way.  6a  6b  7a The students went ahead...  7a The students went ahead and connected the sway bar to the lower control arms before using a jack to raise them in place with the DSE springs compressed (with a modified inside spring compressor) and connect the upper control arm to the spindle...  7b ...With stiff springs...  7b ...With stiff springs this can be a difficult task, but the crew made use of a 4-inch washer instead of the bottom hooks on the compressor and the shock opening in the A-arm. Last, the tie rods were reconnected to the spindle.  8a The chassis brace was...  8a The chassis brace was bolted to the K-member and (eventually) the front frame rails using existing holes, as did the adapters for the front sway bar...  8b ...The triangulation is...  8b ...The triangulation is much needed since as you look back at the chassis, you can see that besides the K-member and (missing) trans crossmember, there isn’t anything to tie it together laterally (until you get to the rear). If clearance allows, we’d love to weld in some additional bracing later on.  9a Getting started on the...  9a Getting started on the rear suspension, after unbolting the sway bar senior student and star pupil Eric Mitchell used air tools to make quick work of the control arms (with the rear end supported)...  9b ...With the control arms...  9b ...With the control arms and shocks unbolted, the rear end was free to drop out from the frame.  10 DSE’s Speed Kit (PN 043110)...  10 DSE’s Speed Kit (PN 043110) for the rear suspension is a little less intense than the front since the Buick uses a basic four-link setup. Tubular upper and lower control arms use Swivel-Links instead of polyurethane or noisy rod ends, which also allow easy pinion angle adjustments. The springs provide a 2-inch drop and come with new jounce bumpers, meanwhile the shocks are a simple design with modern valving technology to keep the tires planted. The sway bar is an adjustable 11⁄8-inch diameter that can provide up to 1,422 lb/in at its stiffest setting.  11 With the rear end unbolted,...  11 With the rear end unbolted, the upper and lower control arms could now be bolted to the frame in preparation for reinstallation. Note that the upper control arms connect to the rear end with a bracket, and the bushings are retained by the housing. We’ll have to replace those cracked and crusty puppies at a later date since they are the only potential weak link in the suspension.  12 The DSE springs were placed...  12 The DSE springs were placed on the perches, and the rear was raised into place prior to bolting up the control arms and shocks with the sway bar loosely held in place by its U-bolts. Prior to final chassis assembly the upper arms will have to be adjusted for proper pinion angle.  13 Here you can see how the...  13 Here you can see how the DSE sway bar actually connects to the frame rail instead of the control arms (like the stocker), via holes that the crew had to drill. With the lateral loads our G-Machine will be seeing, the stock style connection would prove problematic as it stresses the control arms and their bushings to cause deflection.  14 The finished product has...  14 The finished product has our G-Machine well connected, and we can’t wait to get out on track—plenty more work to go, though. Towards the top of the shot you can see our new floorpan from Summit Racing, more on that in a future issue.
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