jaydubya

My 82 911SC currently has 22/29 mm torsion bars and Bilstein sport shocks (might be Bilstein HD on one end, not positive). I'm getting a large amount of body roll through turns while running what I consider to be as much sway bar as can be used safely. As one of my winter projects I'm going to go through the suspension for what will hopefully be the last time for a few years .

I want to upgrade to either 23/31 mm or 23/33 mm torsion bars. Anyone out there want to offer arguments for one way or the other?

I know I'll need new shocks all around. Most people seem to go with revalved Bilsteins. Are there any options for single- or double-adjustable shocks for our cars? I had a set of single-adjustable coilovers on my other car for a while and I really liked being able to adjust the car's transient balance via the rebound adjustment. I cannot have spindle height adjustment or use coilover springs in my race class (PCA G stock).

For reference, here are a few photos of my car showing the amount of roll I'm getting. The first one is in a downhill, off-camber corner:



Here is another 911 in the same corner:



A different corner:





Thanks,

Jeff

earlyapex

Jeff,

I just went through this myself. First of all, are you racing and if so what class are you in or aiming for. The rules will determine if you can go with adjustable shocks and/or remote cannister shocks.

You probably have HD's up front and Sports in the rear. The shocks have nothing to do with the amount of body roll that you are having. This is what your torsion bars are supposed to do. As it stands, your current torsion bars are too soft and your shocks are not vavled propperly for your torsion bars and track use. Where to from here? Again, that depends where you want to end up?

If you don't care about car classification, then the possibilities will depend on your budget. The relatively cheap and easy answer to your question is to keep your current torsion bars and sway bars (what are you using?) and send your shocks to Bilstein to be revalved. You want to think of your suspension as a system, as changing on variable will affect all the others. I say this because some shops like softer torsion bars and use stiffer sway bars to control body roll (i.e. Smart Racing Products). Others use stiff torsion bars and softer sway bars (i.e. Rennsport Systems, aka Steve Weiner). You need to stay with one style of car setup so you don't get lost.

I went with 23/33 Sander torsion bars. These are the biggest off the shelf bars that they make. I used Steve Weiner as a sounding board and leaned heavily on his advice to set up my car, a 78 SC. I ordered a custom set of JRZ double adjustable struts and shocks from him. The fronts allow you to raise the spindle heigth and are remote canister. The rears are not remote canister. This is an expensive option. Send me a PM and I can give you numbers. The alternative to JRZ's in Fox shocks and struts sold by Smart Racing Products. SRP did back to back comparisons of off the shelf Bilsteins, custom valved Bilsteins, and Fox shocks/struts at Sears Point in a class leading Carrera. The Fox shocks were worth several seconds per lap over the custom vavled Bilsteins which were of course faster than the off the shelf ones. The Fox products are much cheaper than the JRZ's and are a viable alternative.

Got extra money? Want the ultimate suspension for your car? Go with a full ERP suspension, replace the torsioon bars with custom springs and JRZ shocks/struts. This is the direction I went with my SC. I'll be competing in PRC GT3 or 4 next year. This system all transform your car.

earlyapex

Where's your tail?

jaydubya

Hi Eric - great info, thanks!

My car is set up for PCA club racing in G stock, so I need to stay within the limitations that they set. So I need to stay with torsion bars and keep my spindles at the same height.

Sounds like your vote is for 23/33 - cool. Did you ever consider the 31 mm for the rear?

My initial plan was custom valved bilsteins for whatever new t-bars I got, but then I started thinking that it might be worth looking into adjustable shock options. I *think* they are allowed in the PCA stock classes as long as the spindle height is not changed or adjustable.

How has your setup worked out for you? Did you go straight from stock to 23/33 tbars or did you have an intermediate setup before? If so, how was the change?

Thanks!

Jeff

jaydubya

Still no rear spoiler yet It didn't seem to slow me down at the MMP PCA club race - the other 9 SCs all had tails and I didn't, but I still managed 2nd in the enduro and 4th/5th in the two sprint races (for the latter two races, I had to start at the back of the pack due to being under-weight). So I figure I'll get around to the spoiler but spend money on other things first...

Gary R.

I'm running 23/31 with Smart Racing adj. sways and custom valved Bilsteins, no complaints.

jaydubya

Thanks Gary - two trusted opinions, two different setups What steered you to that tbar setup versus bigger in the rear?

Gary R.

You could fit what I knew when my shop built my car in a matchbox..

All I can say is that my Sensai, Dan Jacobs, builds winning G Stock cars and this is part of his formula. The torsion bars, SR sways, the way he has the shocks valved, the strut brace/camber bar he uses, the camber and alignment, to the 18" wheels all go toward making a great handling car when mixed together by him.

I'm not seeing an enormous amount of body roll in your pics, but maybe that's just me.

jaydubya

Gary - I understand about the matchbox
Here's a better side-by-side comparison between my car and the other car:



I re-read the rules and found out we need to stick with stock strut housings in the front for the stock classes. Here is what the rules have to say for the stock classes:

B. Shock absorbers are free providing they are of the same type, using the same pick-up points, as supplied by the factory.

And if one moves to prepared (i.e,. up from G to F):

B. Non-factory shock housings set at factory settings are allowed.

I think that just leaves the revalved Bilstein inserts as the only option for me for the fronts, unless there is some company that makes adjustable inserts for the OEM Bilstein housings? I wonder about the rears - could we replace the rears with adjustables such as JRZ or Fox since there is really no "factory housing"?

Jeff

Larry Herman

I ran my old Carrera with 23/31 torsion bars, Bilstein sports factory revalved to match, and 22 mm front/19 mm rear sway bars. It produced a winning setup in the late 90s. After running my RSA though, I feel that it could have been much stiffer (one of the drawbacks with torsion bars on the "heavier cars"). If I had it to do over again, I'd probably go with the 23/33s, an even bigger front sway bar to balance the car, and Moton 3 way adjustables.

jaydubya

Hi Larry - thanks for your response. I am leaning toward the 33 mm rear. If you look at the spring rates associated with 23/33 mm t-bars:

diameter lbs/in

23 250
33 427

That's really not a lot of spring rate compared to what one would use on say a C2 for track use.

As far as Motons - well probably out of my budget, and based on the rules I posted above probably won't fly, at least for the fronts.

It appears that revalved Bilstein cartridges may be the only available option for the pre-89 911s in stock PCA classes.

Cheers,

Jeff

Larry Herman

Yeah, thats really light considering that my car's spring rates are north of 1000 lbs/in. It's barely ok for a 2000 lb 911, but very weak for a stock weight SC. It was even worse with the Carrera.

earlyapex

Jeff,

Every shop has their own setup. You can take a look at two very different setups from a couple of very well respected CA shops and see that they differ in torsion bar and sway bar sizes.

http://smartracingproducts.com/
http://elephantracing.com/

I went with 23/33 torsion bars to maximise the effective spring rate. You simply cannot take one part of the system separate from the rest. The entire suspension has to be thought out to work together. I went with Steve Weiner's (Rennsport Systems) setup and I was very happy. That is until I wanted to go GT racing. The car is appart again so my 06 season was cut short. Next year should be a blast.

Talk to Steve Weiner. JRZ can make custom shocks for you that will work better than Bilsteins. You'll need to talk to him about the restrictions for you car class.

jaydubya

Thanks Eric. I've been studying both web pages all summer for various reasons

I'm thinking that bigger is in fact better for our cars. The spring rates that we can get with t-bars are simply not that great compared to what a coilover car would use.

The biggest bars now available are 24/33 from Elephant Racing. That gives an effective front rate of 296 lbs/in and a rear rate of 427 lbs/in. Rear:front stiffness ratio is 1.44, versus my current setup which is 1.21.

Of course any change will be matched with appropriately valved shocks and then tuned to give the car balance I want with the sways (and shocks if adjustables are legal).

I'll call Steve Weiner tomorrow and see what he has to say.

Cheers,

Jeff

earlyapex

Steve has been a great resource. Tell him that I said Hi!

I've got Sander 23/33 hollow torsion bars coming off my car soon. Let me know if you're interested.