coilover spring rates

[JUST CUSTARD PLC]

what are folks with coilovers wearing this summer ?,
answers in pounds feet if you please (no euro !)

[clivew]

500lbs/in or 8.9kg/mm Front

450lbs/in or 8kg/mm Rear

[JUST CUSTARD PLC]

Thanks Clive,
How do these figures compare with std car, HKS or Eibach springs ?
Pressume these are "fast road" figures ?

[clivew]

The spring rates that I use are more track orientated, they are too hard for everyday road use and no good on bumpy roads, I have tried lots of different rates and found 400lb/in front , 325lb/in rear a fairly good compromise, not bad on the track and devastating on the road! The thing with suspension is that what one person thinks is a hard set up is a soft set up in anothers eyes.

Standard spring rates are 280lbs/in fr, 308lbs/in rr
Thats not a mistake by the way harder rear than front.

Eibach rates are 171lb/in rising to 232lb/in compressed, front and 143lbs/in rising to 312lbs/in rear.

[Rallyman]

Sorry, my figs are in N/mm, but I hope my comments helps.

I tried my Proflex with 90/80 N/mm and it was too hard for road use. Now I am using 70/60 and it's a much better compromise, although still a bit hard for bumpy roads.

If you want the car for mixed road-track use I would not go for harder springs than 70/60, unless the roads you normally drive are very smooth.

Note that with harder springs you are putting much more stress on the chasis, and if you go to a track with hard springs and slicks, you'd better have a reinforced shell and a rollcage (like Blade or Claudius).

[Blade]

I too have run various.

most extreme was 550/550

Not sure what I am running now with the ohlins as there is a discrepancy in the documentation. I thought it was 485/372, but according to the docs it is 515/400

It feels a good compromise, as i have uprated anti-rollbars for more roll stiffness. I suspect i will end up with 550/500. 550 is too hard for the rear IMHO

Also had 450/400 at one point, also good.

Get linear springs. Progressive or double progressive are not good IMHO

For a road car, 400/325 as clive said would be a good compromise, especially if you use dampers with adjustable bump and rebound. One point to make is that different suspenders use different methods of control. Ohlins use softer springing with harder damping (which i believe is the technique lots use) with stiff anti roll bars. Too stiff springs will cost you traction. Getting the balance right is difficult - and so much depends on driving style.

Don't forget geometry plays a big part too.

This is too complex a subject really :(