jeff91C2T

I've got a 91 911 Turbo which has (or had) the H&R Carrera C2/C4 suspension upgrade. I spend a fair amount of time on the track and would like to go to a stiffer suspension. Specifically, I get a tremendous amount of squat on acceleration with this setup. The shocks are Bilstien...

I came across Bill's upgrade to the Carrera RS suspension and think this might be what I'm after (Bill are you out there???). Can I just buy the springs and install over my existing struts and shocks. If so, what are the part numbers???

Or is there a better option? I'm open for any and all ideas...as long as it's a harsher ride:-)!

PhilW

I would also like to learn what others have done. I did a search but came up light. I am considering:blabla: camber plates, solid bushings, limited travel shocks and lowering springs, I have cup sway bars. This would be for a 1993 C2 RSA that is becoming a track only car, except for the occasional agricultural excursion <img border="0" title="" alt="[Eek!]" src="eek.gif" /> .

PS. Whoever said to buy a C2 over a RSA and to spend the savings on upgrades that you'd make to either car is just way to locigal to be tracking a car. <img border="0" alt="[icon107]" title="" src="graemlins/icon107.gif" />

Drew_K

I have 92 C2 and just had H&R 965 springs, Bilstein HD's, a strut bar, and TRG front camber plates installed. The camber plates include monoballs, so the struts have no rubber remaining. At the stock height, I couldn't get more than about 0.6 degrees of camber in front. My alignment is now set at 2 degrees all the way around, and there's still plenty of adjustment range left in the camber plates if I ever need more up front. My suspension was bone stock prior to the changes.

The car sits about an inch lower now, and turn-in is definitely better as is the overall level of grip. I've done one autocross with the new suspension, and I think I ran about a second faster based on how I did relative to the other regulars. I'm still adjusting to the new suspension though, so I think I can go quicker.

The street ride is very marginally worse. I would say it's a mild upgrade, but a great compromise for a 50% street 50% track/autocross car. I'm taking the car back next week to have the front A-arm bushings replaced with steel monoballs. That should make for a crisper turn in. I've always thought my car was a little unresponsive turning in, but it turns out that my bushings are shot.

I have a feel I've started down the dark path of turning my C2 into a pure track car...

Bill Gregory

Jeff,

Yup, I did install the RS suspension as described <a href="http://www.porsche964.co.uk/technical/rs_suspension.htm" target="_blank">here.</a> Having had a torsion bar 911 prior to this one, I miss the crispness of taking a set in a turn, which progressive springs can't deliver in the same manner. Progressive springs are designed to deliver two rides - one on the comfier side and then the hardcore side. On the track you have to move through the progressive part of the spring to take a set in a turn. The benefit of this is that you have to be consistent or the comfier side of the progressive unsettles pretty easily - and that has value in learning to drive smoothly on the track.

I'm considering switching over to a Hypercoil linear spring solution. That would include new hats and bases for the springs, and the springs. I think the non-spring hardware can be had for around $200, and the springs are maybe $50-$60 each (Just got the Smart Racing catalog in the mail the other day, which is restimulating my thinking on this project). Considering around 325-350 lb spring in front and 550-575 lbs in the rear. Of course there are tradeoffs in anything - the RS springs give nice response on the street, and since this is a dual purpose 964, I want a spring rate more optimal for the track without rattling my fillings. A nice thing is that Hypercoils come in almost any pound spring you want, so you can change them without breaking the bank each time. The Hypercoil website is <a href="http://www.hypercoils.com" target="_blank">www.hypercoils.com</a> .

For spring rate comparisons, the RS rates revolve around 245 lbs in front and 400-450 lbs in back. The RS 3.8's are 177-217 lbs front and 375-459 in back. H&R Cups are 455 front and 685 rear, and the American Cup car racing springs were around 500 front and 700 rear. The H&R cups also have helper springs on them.

Of course shocks and springs need to support each other. Here's some information on shocks we use. The values are read as rebound over compression, ie, the first number is the rebound value with the second being the compression value:

964 to '90 (Bilstein HD)
...Front 332/104
...Rear 274/122

964 to '94 (Bilstein HD)
...Front 332/104
...Rear 277/124

964 Carrera RS
...Front 259/84
...Rear 415/237

964 Cup
...Front 220/67
...Rear 379/172

964 RSR (3.8L)
...Front 237/96
...Rear 402/216

Jeff, if you wanted to stick with a Porsche solution, I'd look at the RS 3.8 setup, as it used a Turbo body and much of the Turbo underpinings. The Carrera RS setup, btw, needs matched shocks and springs, as the whole setup is shorter than the stock setup.

Didn't mention the rubber bushings that Drew is addressing. ERP replacements for the softer stock rubber front and rear are one option. They aren't sealed, but Cary Eisenlor, who designs them, suggested to me using the goop you dip tool handles in to seal the sides. Or you can buy the RS arms, which in the rear cost around $1200 each, versus $600 for the ERP rear bearings.

Also didn't mention......who said something about the dark path??

jeff91C2T

Bill, excellent advice! You've touched on area's that I hadn't thought about. In particular, I autocross and the nature of the progressive springs is what I don't like.

I've got my struts and shocks in the shop right now going to what your thinking about. The spring rates I'm looking at are 450 front and 600 rear. They're trying to pull together the hats and bases but are taking they're sweet time, which is why I thought I'd see if there were other options. Sounds like this is what I want though. I'm going to stick with the linear rate springs and see how it goes. I'll keep you posted.

Bill Gregory

Jeff,

You might contact either Smart Racing (www.smart-racing.com) or San Diego Motorsports (www.blackforestautomotive.com/Motorsports) for hats and bases. I believe they both carry Hypercoils too.

Once installed, look forward to hearing how you find them.