coilover kit, what spring rates to choose?

[quattrostyle]

I want to order an Ground control coilover kit but I don't know what spring rates I should choose.

Here is my project:

audi 90 quattro type 85
S2 drivetrain + engine
maybe with a larger rear swaybar

The car won't be used for trackdays I want to use it as an daily driver so it mustn't be harsh, one forummer mentioned 300 front and 350 rear, but then another said 350 front and 450 rear.

It would be nice if the car is less understeerd but I don't want it to handle like a BMW, so what do I do?

And then which shocks should I use Bilstein or Koni? And why?

thanks

[Rusty]

Just had a quick look as I'm interested in this sort of stuff...

There are plenty of typ85 90q projects on motorgeek. Have a look and see what people have used, from memory Ive seen 350lb and 400lb quoted but you'll have to have a look for yourself to check.

Looks like anything between 300lb and 400lb will work, softer for road use, harder for track use. Sounds like some are running up to 800lb for track use but that's too harsh for road. Linky. There's another thread guessing that the standard springs are 175lb front and 200lb rear.

To get understeer you want stiffer springs at the front than the rear. Other things that will help understeer more are stiffer front ARB, no/weaker RARB and larger rear tyres relative to the fronts (although matching the rolling raduis will be a PITA).

Personally I'd use equal rate front and rear springs and get the understeer with the ARB setup as this is easier to alter if you decide that you want more neutral or BMW handling

Personally I quite like a car to oversteer as with quattro you can enter a corner off the power and get lots of turn-in tending to mild oversteer and then the car straightens up as soon as you get on the power, not sure how much the TORSEN helps with this but it's both fun and fast as you can get on the power earlier and so carry more speed out of the corner. But that's just me!

[quattrostyle]

yes a bit oversteer is not bad, but I drove a friends E30 someday in the wet and I thought it was rubbish

[Rusty]

You'll not get those problems from the front-heavy Audi.

[quattrostyle]

well how about front and rear same spring rates and move the S2 ARB to the rear and mount a 90 10V swaybar up front, would that make any sense?

[Rusty]

Stiffer RARB would induce oversteer. I have a 26mm up front, 25mm at the rear, it's quite lively when driven hard.

You also have the problem that the typ85 struts won't work work with the later B4 style ARBs as the later ARBs attach to the strut, not the wishbone. Perhaps an early CQ20V (25mm) FARB and a standard RARB would be a good setup with equal rate springs all round?

[quattrostyle]

I have a full S2 driveline, so the ARB's won't be a problem I guess

[Rusty]

You'll be ok then. RS2 front, 24 or 25mm rear.

[quattrostyle]

I had a read at motorgeek and the guys there use bigger RARB then FARB

[quattro84]

Like Andy says, Big RARB will help to get the oversteer-effect. OEM FARB & S2 RARB might do the trick.
I suggest to try different setups.. Damper/Spring/ARB all relate to each other.. They are a matched pair of parts. (A Softer spring means more travel under similair load in comparance to a stiffer spring, More travel means bigger torsion-angle in the ARB beam and possible more damperfriction due to bigger travel/acceleration.)
I am looking up some setups that the Skandinavian Typ85's use and i'll post them if i find those.

[quattrostyle]

thanks quattro84, tell me more on MSN