TT Oversteer

I have been slowly but steadily collecting parts for a suspension upgrade for my '77 3.2 conversion. I'm going to break this down into two separate projects starting with the rear then the front. I'm trying to keep the costs reasonable so there will be no "blank check" for 935 spring plates, coilovers, etc, etc,etc. Here's what I have decided on:

Hollow torsion bars, 21mm F and 28mm R
Elephant Poly Bronze front and rear with front low friction mounts
Rear monoballs, still undecided on the front monoballs
Wevo RARB consoles and Elephant/Tarret rear swaybar
Front will get a Tarret through-body adjustable swaybar later but for now has the stock underbody bar
Turbo tie rods with rack spacers for bump steer
Euro ride height
16x7's all 4 corners with 205/50's until I can get some flares on the rear later
Front strut brace already installed
Bilstein shocks will be sent to Bilstein for a rebuild and revalve

This car will be used for street driving with (hopefully) some autocross and DE.
It will be going on a soft core weight loss program with a target weight of 2600lbs.

So........here's the question for you experts and racers: Based on this setup what would you recommend for shock valving compression and rebound for both front and rear?

Peter Zimmermann

Your T-bar size choice puts you right on the cusp between using HD or Sport version Bilsteins. Also, your driving style really matters with this choice, so you should probably call Bilstein (still in San Diego?) and tell a rep about your setup and what they recommend. My set-up on my avatar car wouldn't do much good for you (23/31mm T-bars + huge sways), but I'll look for my notes anyway. It's been a number of years, but I'm pretty sure that my final valving had the jounce and rebound strokes much closer in value to each other than the original Sport versions... Post what Bilstein suggests and it might wake up a few sleeping brain cells!

TT Oversteer

Thanks Pete, the shocks will be going to Bilstien and I'll post what I find from them. I'll request a shock dyno report as well.

TT Oversteer

The rear suspension upgrade is almost complete. I sent my rear shocks to Bilstein for a rebuild and custom valving. It's really a great value. They rebuilt the shocks, exchanged the piston rods with a newer version, and set the compression and rebound valving specifically to my car's weight, torsion bar size and my stated driving style. This was all done for $75 per shock. Here's a copy of the dyno sheet for one of the shocks. The other one is virtually identical. The dyno measures compression and rebound in mm/sec. vs. force in Newtons for both compression and rebound strokes. I'm not sure how these numbers compare to a stock "HD" or "Sport" Bilstein but maybe some of the experts can chime in. With the 28mm T-bars, rear monoballs and ploy/bronze bushings the ride is firm but not harsh at all. Very tolerable for the street.

Chris M.

This is great info as I'm about to send Bilstein some shocks for custom valving as well. I will have 23/33 torsion bars so I suspect they'll recommend different numbers. Do I need to be able to tell them specific values or do they just ask about the car and do all the math? Whom did you contact?

Now if I can just find some used fronts to send them....anyone??!!

TT Oversteer

I sent the shocks to Bilstein in Poway, CA. There was no specific contact person that I spoke with. Just go to bilstein.com and click on the "services" tab. Download the acrobat work order and specify what you want done. There wasn't a lot of communication or feedback from them. I had to call and do some follow up work to get exactly what I wanted. But the work was excellent and done for a great price. The only data they need is the weight of your car, spring rate (t-bar size is good enough), and driving style you will be using the car for i.e. street, street/track, pure track, etc. If you ask they will provide a dyno sheet like I posted above for your shocks free of charge. Plan on at least 3 weeks for the whole process.

aeshultz

A question here for Pete and others;
I'm about to put Bilsteins on an otherwise stock '88 Coupe. I probably _will not_ upgrade T bars (at least not now) but _will_ use the car for an a few DEs. Would I be better with the HD or Sport versions? I just sold my race car, and I know that this will equal that type of setup - but do want to keep the car close to stock if possible. What say you?