mx5cartalk.com

Can anybody out there point me in the right direction for spring rates for track use?

I have an NA8, I also have a few sets of bilstiens in the shed some NA and some NB, I am just putting together a budget package so that I can convert my rally car to a track car for the phillip island 6 hour.

I basicly just need a rough Idea on spring rates eg 300pound front and 250pound rear etc. I am assuming that I will have to put the rear sway bar back in as well.

Any help would be greatly appreciated.

Thanks Dave

6kg/9kg will work well with stock swaybars if that helps keep costs down.

Dann

Many different combos of springs and sways will work. Can you tell us what springs and sways you've got already on the car and in the shed and what shocks/coils you use then we could give you some pointers.

Ok

Currently the car runs NB bilstiens front and rear, Fronts bump and rebound have been altered for rally, rears are standard.
Springs are kings standard height in the front with a 25mm spacer under the spring platform for height, rears are standard springs with the circlip groove raised 25mm (onceagain for height).
Front has a 24mm whiteline swaybar and the rear has no sway bar at all.

I have a standard rear sway bar in the shed somewhere.

I also have adjustable spring platforms and some king pro coil springs that are 300 pound (pair) and 250pound (pair)

I have a set of standard bilstien NA and also NB shockers in the shed as well.

I will be running 15 inch simmonds wheels with bridgestone steet legal racing tyres and I am sponsered by trackside race and rally tyre service so the alignment is no issue.

Does this info help?

Thanks

Dave

OK, then I assume you have:
- front 240lb/in Kings in the car and another front set of 300lb/in, both sets non-progressive
- rear 94 lb/in stockies and another set of non-progressive 250lb/in
- a 24mm whiteline front sway, and
- a 11mm NA8 rear sway

Is that right?

Then to me the best combo looks like 300/250 F/R springs with the both 24/11 sways in. That gives you a roll stiffness of 1,740 lb-ft/deg which is twice as stiff as standard and a front roll couple of 60% which is the same as a standard NA8, meaning it will be slightly understeer biassed on the track but not too bad. I can't find any other combo of the bits you've got which makes the thing at all reasonable. In fact I can't work out how you drive it now.

I probibly should of mentioned that the car is a dirt/forrest rally car not a tarmac rally car.

I can purchase some new springs if neccessary and if so should they be about 450 pound and 375?


Thanks

Dave

If you were going to keep focusing on rallying why then bother buying springs for a one-off track event? I would have thought that the object of the 6 hour was to produce consistent times, not necessarily the fastest times. You can get a pretty good setup with what you've got already.

I was assuming that having the car so high on the track would create excessive body roll, was just hoping to obtain a more track friendly feel for the weekend.

Thanks for your help anyway

Dave

Oh, thought the adjustable spring platforms would sort that out.