help advice please suspension/spring rates

mx5rally · Postby **mx5rally** » Mon Jul 09, 2012 8:56 am

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

Postby **NitroDann** » Mon Jul 09, 2012 9:22 am

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

Dann

manga_blue · Postby **manga_blue** » Mon Jul 09, 2012 9:42 am

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.

mx5rally · Postby **mx5rally** » Mon Jul 09, 2012 10:58 am

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

manga_blue · Postby **manga_blue** » Mon Jul 09, 2012 11:22 am

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.

mx5rally · Postby **mx5rally** » Mon Jul 09, 2012 2:36 pm

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

manga_blue · Postby **manga_blue** » Mon Jul 09, 2012 3:00 pm

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.

mx5rally · Postby **mx5rally** » Mon Jul 09, 2012 3:24 pm

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