Spring rates..

[Jhonno]

What sort of spring rates are people running? (For those that actually know..)

Tempted to get 2 sets, 1 for road, 1 for track, but not sure where to start, I currently have AC Schnitzer springs which are pretty good for road use imo, but no idea what rates they are!

Sadly havent been in any track orientated setups that are used on the road to see how harsh they ride/crash/bounce etc

[Beemer Redeemer]

Hi Jhonno,

If it helps, I have just bought a Gaz kit. Dave @ Gaz recommended i used 600 front, and 300 rears.



Car is a 320i (running in PBMW Cup) with Custom Cage multipoint weld in - going to all 4 strut turrets.

I haven't yet diving the car on track or even on road so cannot comment on whether these are the right setup for me. But may help you get an idea of what people are running.

Cheers
James

[Jhonno]

that seems to be about the rates they are recommending for track use then.. bit too harsh for the road me thinks, seen a vid of a car running those rates on the road

im thinking 475/500 up front atm

[mikekean]

they recomended 500 front 250 rear for me as a rally setup as you need it a bit softer for the bumps.

[oldroydsr4]

I did quite a bit research on this and rear are different depending on if you are running 'true' coilovers or not.

If you are as seen in the pic above 300 is about right.

However i'm not (using standard set up with spring perches) ireland engineeing advised front 600 front and 550 back for a track setup.

They only use eibach so they were n't cheap and I'm yet to try them as the car is still being built but they 've being doing racing e30's for a long time so i took there word for it.

[handpaper]

The H&R Nurburgring Kit (which I'm copying) is 675 lb/in front, 620 lb/in rear, using the OE rear spring perch.
To convert from OE to coilover rear, you must divide by the square of the movement ratio.
For an e30, the centre of the spring perch is 300mm from the pivot axis of the trailing arm; the shock bolt (where a coilover spring would act) is 500. So the ratio is 5:3, the square is 25/9 or 2.78:1 and the equivalent spring rate (for the above kit) is 224 lb/in. This is quite soft for a track/race spring rate; it's because the 'Ring is a bumpy place
I've used this setup on the road for a week now, it's not too bad. The biggest issue is having enough damping, especially on the front, which is very firmly sprung - you'll need reputable adjustables (Gaz, Koni, Spax) and you'll need to wind them up most of the way.
A mate described the ride on a car with too much spring and too little shock as "bobbly" - you feel as if your eyeballs need dampers of their own

[UweM3]

My spring rates are 680 front and 1000 rear (non coil over) that is the softest Grp N setup
The H&R values, are you taking them from internet information or do you know somebody who'ed measured them? I had a little "manual" check and I am a bit sceptic about the rear beeing so soft (compared to the front), I think it's harder than 620. My current rear spring is 560 and feels much softer compared to the H&R sprung car I have tried.

[Jhonno]

I have lovely H&R roll bars, so i dont need loads of stiffness in the springs to stop it rolling, i'd rather it was compliant, it will spend most of its time on the road, with trackdays/'Ring for stretching its legs

[UweM3]

I have lovely H&R roll bars, so i dont need loads of stiffness in the springs to stop it rolling, i'd rather it was compliant, it will spend most of its time on the road, with trackdays/'Ring for stretching its legs

Roll bars are for fine tuning, not to counter excessive body roll. Too stiff roll bars and soft springs --> no good! Like having a solid axle.
But each to their own

[Jhonno]

hmmm.. yeah just been doing some reading up on suspension setup

Disadvantage of stiff roll bars is unloadin the inside wheels = less grip, which you dont get with stiffer springs, but too stiffer springs means it doesnt ride bumps so well (for road use)

the other complication i have is the extra weight of the S50 up front

[UweM3]

hmmm.. yeah just been doing some reading up on suspension setup

Disadvantage of stiff roll bars is unloadin the inside wheels = less grip, which you dont get with stiffer springs, but too stiffer springs means it doesnt ride bumps so well (for road use)

the other complication i have is the extra weight of the S50 up front

I am sure you are follwing this?
http://www.e30zone.net/modules.php?name ... ic&t=96423

[Jhonno]

Yup.. Been reading that, some good stuff in there