got a less expensive rear springs than Ohlins on mine but if your in Europe
https://www.ohlins.eu/en/products/au...8010-31--5766/

 

Yes I found that link, exactly what I would need... But this site does not deliver in France. And ohlins.fr does not have this reference on the website. I will contact them...

 

Why not just buy 2.5ID, 8" long, 560LB/IN springs from Eibach? Easily available on most authorised part sites or from Eibach direct.

Your S2000 probably will never feel as stable as a 350Z. But it should feel pretty locked down with that suspension and a decent set of tires.

Having less rear toe in will probably help.

Check your tire pressure as well.

 

I wouldn't call the front kit useless but I don't think it's really needed.

 

. Less rear toe and BSK may help. But the S2000 is not going to drive like the 350Z. That's why we like it.

 

Thank you all for your answers.
I can understand that the S2000 will never be as stable (and annoying ) as the 350Z.


So, the ways to optimize will be:
1/ Find a pair of 10kg rear springs: I would like ohlins springs just for aesthetics, but I will also look at other options for price reason. Is there no quality difference between spring brands ? I can fin springs from 35$ (BC-Racing) to 70 or 100+$ each ! with same theorical specs...
2/ Fit Megan Racing or Hardrace rear BSK
3/ New alignment with less rear toe in: 0.2 degrees total toe in

For information, here are the results of the "WheelRate" sheet:
Car MY2002, DFV 10/8kg, oem ARBs:



Car MY2002, DFV 10/10kg, oem ARBs:



Car MY2002, DFV 10/10kg, Eibach front ARB on high setting:




What I understand from this sheet is that near 50-50% balance will be really oversteering and near 60-40% will be much more safe and neer to understeer. Right ?
But what about Natural Frequency ? I don't know how to understand these results ...

 

From this sheet, replacing my rear 8kg springs with 10kg would:
1/ take the wheel balance from 57/42% to 53/47% : isn't that going the "wrong" way for the overall stability of the car ? I understand this will cause more oversteer, right ?

2/ take the natural frequencys from 1.68/1.49 to 1.68/1.67 : what is the benefit of that ??

 

I would try alignment first, with nothing else, and see what that does for you.
IMO going from 0.67* to 0.20 degrees total rear toe-in should noticeably change handling feel, then you can go from there if you still want to jack with other stuff.

Yes, going stiffer on rear springs will give "more oversteer". Stick with 10/8 for now I'd say, and later if you want more front grip and a little more roll stiffness, w less understeer 10/10 springs would be something to try.
I wouldn't worry too much about natural frequencies, but be aware of the wheel rates. IMO aim for wheel rates slightly more forward-biased than front/rear weight distribution.

BSK might require some setup to minimize bump steer. Also it seems like there have been BSK failures at the track? Might research that...
I stuck with the factory AP1 bumpsteer and just kinda got used to it... Reduced rear bumpsteer would be better but IMO not strictly necessary. But if you are looking to get rid of weird handling characteristics, yeah...

 

Thank you very much, I like your help.

You are right, I will go step by step with modifications.
First (cheap) step might be:
- get ride height back to only 20mm drop: this will help with getting the car in my garage without damaging the front lip, and this will naturally reduce bumpsteer as well.
- improve the rear spring preload to SakeBomb Chart.
- get new alignment with rear toe in correction.
- drive, drive, and drive again to get used to it

 

If it helps, here is my alignment for track/road, zero tram line and holds the road nicely over the bumps. 03 plate with BC coilovers 10kg/10kg and 17" michelin pilot sport 4, 255/225