Here are some details on pieces I used in the rear suspension on Buford. I think you can also get some useful rear suspension tuning info from the following as well:
I used upper and lower trailing arms from TRZ Race Cars (I have parts from both AutoFab and TRZ – both companies have really, really nicely finished hardware). This first photo shows the rear end setup before the gas tank was installed and before the brakes and other pieces were completed. I spent a lot of time concerning myself with the suspension geometry on the car, and as I probably mentioned previously, I’m not big on altering the instant center by a huge amount. I’ve seen so called “lift bars” actually oval the holes in suspension mount points. Folks in the know figure this is because the lift bars are actually attempting to rip the rear end out of the car.
This photo shows upper trailing arms from both TRZ and AutoFab (I picked up a set of uppers and lowers from both companies). TRZ pieces (the ones I installed in the car) are at the top. These components are very nicely welded, have great machining and are finely finished. Both companies also have outstanding reputations within the stock suspension “fast street car” drag race crowd too. In this case, I decided to stick with one manufacturer for rear suspension hardware instead of mixing and matching.
What’s appealing with these pieces is the fact they’re easily adjustable. Some people figure you can adjust the factory four link by way of preload (like folks do with a drag race four link – on those setups, you can shorten the upper right bar to increase the pre-load on the right rear tire; If you lengthen the same bar, then more load is placed on the left rear tire.). That isn’t really correct with a stock style suspension system since the factory four link is triangulated, not parallel. In my case (stock style GM triangulated suspension), the upper bars are used to center the rear end housing from side to side (by adjusting one upper). The upper bars also used to set the pinion angle (by adjusting both uppers the same direction and same amount). The adjuster for the top trailing arm bars is shown in this photo (the build quality here on the TRZ pieces is fabulous by the way):
I removed the top bushings and bushing sleeves from the rear end housing and installed a set of spherical bearings from TRZ Race Cars. Actually, I used the billet bearing retainers from TRZ and swapped out the spherical bearings (exchanging the supplied bearings which I believe are from QA1) for pieces from Aurora Bearing. I’ve always had good success with hardware from Aurora. Their good bearings are manufactured in the USA, and they don’t cheap out by injecting plastic into the piece as a bearing surface (more common on Chinese made bearings than you might think). It’s for this reason that Pro Stock chassis builders such as my old acquaintance, Jerry Bickel use Aurora hardware. The good quality Aurora rod ends are definitely pricey, but I figured I could justify it on this build. By the way, pretty much everywhere you see a spherical bearing or non-solid rod end (there are two solid rod ends used for lower shock mounts), on this car the bearing came from Aurora. And there are a lot of rod ends and bearings in use on this car!
The lower trailing arms I used on the Buick are also from TRZ. In this photo, you can see both the TRZ and the AutoFab pieces. TRZ bars are on the top. The big difference is the Delrin (very hard plastic) bushing on the frame side and an adjuster on the rear end side. The Delrin-equipped bar is more street friendly than one with rod ends on either end (less harsh and less noise). Delrin material doesn’t deflect like poly. That means, for a street driven car, it’s a far superior material. In truth, poly bushings cause “stiction” (where the bushing momentarily seizes) and that causes all sorts of traction tuning issues. The lower bar adjustment is to set the wheelbase on the car (and obviously attempt to simultaneously center the wheels in the wheel well). FYI, this setup allows for minute wheelbase changes. And like their top bars, the TRZ lowers have a fabulous build quality.
When it came to the setup, I didn’t use lift bars. I didn’t use air bags. I didn’t use trick springs (the stock six cylinder springs are in the car). And as you’ve probably gathered, I didn’t use revised suspension geometry either. So how do you make these things hook? The key is in the anti-roll bar along with the shock absorbers. To pre-load the suspension in an A or G-Body, a sway bar (anti-roll bar or “ARB”) is most often used. When the car is driving straight down the road, an anti-roll bar is effectively in a “neutral” position. That means it has no effect upon the way the car feels or works (drives, rides, handles). It also has no effect upon ride height. Get on the throttle though, and the anti-roll bar counteracts torque rotation. Increasing the diameter of a stock rear bar or using a weld-in anti-roll bar (like the really cool TRZ piece I used), allows you to tune the amount of torque rotation the car has. The beauty of the weld-in ARB is that you can physically climb under the car and adjust the links that locate the bar to the rear axle housing. That means you can add or subtract pre-load at will. And it’s pretty easy to disconnect or disable should it be desired.
The other key at the rear of the car is the shock absorber arrangement. I wanted a high quality double adjustable shock here. It just so happened that Strange Engineering is now building high quality aluminum body shocks in the USA. They’ve been a Koni distributor for a long time, and it was only natural for them to branch out into shock absorbers. Both adjusters (rebound and compression) for each of the back shocks are located at the base (because of the adjuster size and location, I had to rotate the shock at the lower mount).
In the Buick adjustment is super easy to set. I set the rebound first. For a baseline, I set the rebound adjuster to the hardest (full clockwise) position. This means the shock will be hard to extend. Basically, this means the body will not be separating easily. It’s essentially a very conservative starting point.
Next, I set the compression adjuster to full soft (full counterclockwise) position. This means the shock will be easy to compress. The car will droop at the back (again, a very conservative setting to get started). At this point, I can tune the car for various drag strip conditions. When the car is set up for street use, then its easy to turn both adjusters (rebound and compression) to four or five clicks back from full hard). If there’s a need to firm up the handling for some reason, then it’s easy to simply turn both of the adjuster knobs clockwise. As you can imagine, these shocks from Strange are super nice pieces. It's not necessary to remove the shocks from the car for adjustment either. You simply crawl underneath and twist knobs (no tools are required either).
That’s it for now, but I’ve found a couple of pix of the front end pieces, and I’ll see if I can find a few more. When I do that and find some time to add some captions, I’ll post them here. Til next time!
Wayne Scraba
