docwyte

What are people running spring rate wise on these when you delete the rear torsion bars?

I do drive the car on the street, so I need something somewhat compliant.

Anyone running dual springs on them?

C ANDERSON

550# front 700# rear and yes I do drive it on the street some . Stiff but not as bad as I expected
have another car with 400# front and 550# rear it feels bouncier may be difference in the valving . each set
was valved for the springs .
Clifton

TonyG

For a daily driven street car that sees track time....


Go with a 450/700 using a Weltmeister front bar, set in the middle.... and no rear bar or a 968 3 position adjustable bar.

And send the shocks and struts off to be revalved using those spring rates (it will make a big difference).

And get rid of all the rubber in the suspension.

Run at least a 275 on the front and larger on the rear.

TonyG

Van

I think I used to run 750# on the back of my Turbo S. (I also experimented as high as 1100#.)

It's such a short shock that dual springs would be kind of tough. Plus, with dual springs, the rate is much less. If you have dual 1100# springs, your effective rate is just half that (550#) because for one inch of travel, each spring is only compressing 1/2".

dillon410021

Was at 500lb rear. Upgrading to 750lb rears.

coilbox

I use 450lb fronts and 600lb rear

pontifex4

350lb front and 500lb rear feels surprisingly close to stock in terms of ride quality. It's a bit soft for the track, though.

docwyte

Ok, I have the 968 M030 swaybars front and rear right now and I run a set of 275's all the way around.

Tony, if I put more front bar on, along with bigger (295) rear tires, won't that make the car understeer?

Seems like consensus is 450 front and 650-700 rear spring rates? Where are you guys ordering the springs from?

Oddjob

Last place I bought springs from was eshocks. Seem about as cheap there as anywhere.

http://eshocks.com/hyp_ind.asp?SubCh...h=Q8&SubChar=Q

Also, when you decide on exact spring rates and lengths, send me a PM. I have a bunch of used, near new, and some unused springs that I need to sell off. Hypercoils and Eibachs, mostly 2.25" ID x 8" lengths, and some others.

TonyG

The question is... what are you willing to put up with in terms of ride quality if this isn't a pure track car.

A 450 front spring will allow the car to more around a lot and was recommended because it's not too stiff for daily street use.

If you want to get serious then you'll have to be running at least a 650 front and what ever on the back (depending on what the car wants, depending on the setup).... but I'd probably stick an 850 on the back and setup from there.

Also... get as much rubber under the car as you can get. You can get a 315 on an 11" rim under the back with very little work (fender pulling) with the proper offset. I run a Cup 2 9" wheel widened 2" on the inside, then use a factory 930 1" spacer to push it it giving you a net 1" wider on the outside, and 1" wider on the inside. With -2.5 camber, it just clears.

And... you can do like me and get the AIR 1" wider stock looking glass fenders. This will allow you to use the same 315x 11" wheel with a 1/4" ish spacer on the front :-) And with -2.5 camber it fits perfectly with no rubbing.

315 on 11" wheels at all 4 corners. Now you're talking pretty good level of grip on a R compound tire (I run NT01's) and you'll be able to run pretty fast around a race track... rotate the tires, and get a good solid 3-5 weekends on a set depending on how hard you drive them.

As far as sway bars go.... With my 315 square setup using a weltmeister front bar, and no rear bar, using a 750lbs front and a 1000lbs rear, the car is extremely neutral. This setup is with a V8 in the front.... the setup for a 4 cyl would be different.

Back to your setup....

If you add more bar and more rear, all other things remaining unchanged... the car will have more grip in the rear. So it could very well induce push. but you can dial that out with your spring selection and your sway bar adjustments.

You really sort of have to decide what you want to do with the car, then do the whole setup. The incremental thing is just a big waste of time if you want to go fast around the track because you always end up going stiff with big rubber.

TonyG

superloaf

and all these suggestions are regarding the stiffer valved bilsteins, correct? i've seen they have 500/180 and 360/150 valving---does the valving make a difference? is there a big difference in feel and/or spring handling between the 2? what spring range can each valving handle effectively?

dillon410021

guy on pelican has lots of springs for 100/pair
http://forums.pelicanparts.com/porsc...ings-sale.html

TonyG

The first number is the rebound damping. The second is the compression damping.

You don't need much compression damping because the spring itself slows down the movement.

The rebound damping is how fast the shock extends. The stiffer the spring, the more rebound damping you need and vice versa.

If you look at the two numbers... you can clearly see that the 500/180 is intended for stiffer springs than the 360/150. The difference is substantial.

I have no idea what the stock valving is intended for in terms of spring rates. Nor does Bilstein as the person that designed that setup is no longer alive and nobody there seems to know.

:-)

That said... if you send them to Bilstein with the wheel weight and the spring you want you use they will custom valve them for $75 per strut and $65 per shock. And I can tell you from direct experience... it makes a big difference as I just had mine done (which I won't be using now that I'm running GT3 suspension..... ).

TonyG

mikey_audiogeek

Just to add to what Tony said: you can also tune with roll centre height (by changing ride height front/rear) and track width.

Widening the track at the rear will reduce vertical wheel rate but increase relative roll stiffness.

Amazing what you can achieve with a selection of wheel spacers, c-spanners, and sway bar links - all without changing spring rates. More than one way to skin a cat (not that all ways are equally effective, of course...)

Dwane

I will need a lot of input after December 15 when we(me and mechanic buddy) start working on setup.
Great thread!