stiff suspension options...help!

[s4floorin]

im new to porsches, but i would like to know what i should choose as far as suspension setups.
my car is a 1971 911
it will have a full roll cage, and tracked quite often.

I want a shock that has a shorter travel than normal. I only need probably 4" of travel since i will be running very high spring rates, which shouldnt compress more than a 1/2" at most.
What setup should i look for?
for the front?
back?

If i want something this stiff i will probably have to go away with the torsion bars, right?

please let me know what i should do. i want a car that when you lift it the wheels dont extend so far. i dont need much travel.
what sway bars?
torsion bars?
spherical bearing arms?
.........

blah.
thanks.

[jluetjen]

s4floorin;

Welcome to Pelican Parts BBS!

There are lots of guys who track their 911's here, both with slicks and DOT tires. What tires will you be using?

The other thing that you want to keep in mind is that when a shock runs out of travel (especially in compression), it will cause a sudden lack of traction as the suspension binds up. Not really a good thing. What sort of spring rates (lbs per inch) are you looking for? This will determine if you can stay with T-bars or need to switch to springs. This could get expensive though since coil-over suspensions in 911's (especially the front) limit wheel size unless you upgrade to a 935 style suspension.

A common way to shorten shocks is to saw off the rod and then re-thread it. Alternatively, if you're using Koni's, you can send them to any number of shops to be modified to your specifications.

Can you share some more about your project?

[IROC]

Originally posted by jluetjen
Can you share some more about your project?

Yeah! Why the "really high spring rates"? What do you consider really high?

Mike

[Elombard]

The guys who chimed in first are much more knowledgeable than I. But I will throw a suggestion out. I am assuming you are prepared to spend pretty freely.

If you are not racing I would go with custom valved bilsteins, 22 or 23 front T bars, 31 rear T bars. 22mm (or so) fully adjustable (expensive) sway bars, adjustable rear spring plates and an absolute must is a full compliment of bearings - like elephant racing - strut tops, A arms, Spring plates and banana arms. This will eliminate binding. This will be a very racy set up. IF you want to go with full coil overs (alot of fab work on the chassis) I am not familiar with the spring rates. There are plenty of retailers and people here who could get you started. YOu should post on the autox/race board, I am sure cstreit will have some great suggestions too. Its a slippery slope!

[911pcars]

What I think you need are shocks that are in the middle of their operating range when the vehicle is at rest, and ideally with plenty of suspension travel for the reasons given. Since lowering the ride height moves this midpoint, especially at racing ride height, the usual procedure is to reposition the strut tube relative to the steering knuckle and spindle. You can purchase raised spindles from Bilstein or you can modify some struts to accomplish the same thing. Other front end geometry will also have to be addressed (bump steer and alignment correction/adjustments).

As for springing, the very stiffest setup is from coil springs. The above strut modifications can also include an adjustable coil spring perch. Not sure if you need a spring rate high enough to warrant coil-overs on an early part-time track car, but it's been done. A 23mm front torsion bar should be plenty stiff for most. Wait for more to chime in on this subject.

Hope this helps,
Sherwood
http://members.rennlist.org/911pcars

[s4floorin]

Well im my sedan im running motorsport coilovers; 800# in front/1100# in rear. it compresses about 1/2" at most, and i LIKE the feel it gives.

Im thinking i want somewhere around 700-1000# springs.

Now prepare for the flames. flamesuit on...

I am going to put either a subaru turbo or LS1 v8 into the 911. Either way i am going to build it as light as possible. what do you guys think?
which one? could i make the v8 ls1 handle, or is it a lost cause?

thanks.

[IROC]

Originally posted by s4floorin
I am going to put either a subaru turbo or LS1 v8 into the 911. Either way i am going to build it as light as possible. what do you guys think?
which one? could i make the v8 ls1 handle, or is it a lost cause?

thanks.

Well, I think you just wandered outside of the expertise of most of the people on this board. I have been on the track with some V8-equipped 911s and while they performed relatively well (for what they were), I think it would take some effort to make it handle "well".

IMHO, your spring rates are too high, but that's just my opinion. You need some amount of "compliance" to ensure the tires stay in contact with the track.

Good luck and let us know how it turns out.

Mike

[911pcars]

"I am going to put either a subaru turbo or LS1 v8 into the 911."

No flames, but didn't you think this has a bearing on the spring rate when you first posed the question?

I have a feeling the number of people tracking a V8-powered 911 is fairly small here. Have you tried contacting Renegade Hybrids for their suggestions?

Sherwood

[jluetjen]

I would agree, you want to use RSR front struts (with the raised spindle) to keep your shock travel in the center of it's range after lowering a 911. I also agree that you need to figure out your engine configuration before you worry about your spring rates. Then you need to determine what sort of tires you're going to be using. Once you know the grip level and the weight that you're trying to manage (as well as it's distribution), you'll then be able to start to develop a suspension strategy.

Personally, I'm a big believer in suspensions that suspend the chassis. If stiffer were better, all of the fast racers would be running with steel bars in place of their shocks. Porsches have always been an example of excellent on-track performance from a finely tuned and supple suspension -- with relatively lots of travel BTW. It's generally been the other makes which have had to resort to inordinate spring rates to make up for the geometric issues with their suspensions. Having a car with a supple suspension also makes it a lot easier to drive fast since it provides better feedback to the driver.

I think that it was Colin Chapment (Of Lotus fame) who pointed out that you could make almost any suspension work if you just stopped it from working. That has generally never been needed with 911's.