I dont know what Tanabe is thinking with their spring rates. They lower and then they durastically soften the rates.
I copy and pasted Post number 30
Eibach to produce Nismo Pro-Kit springs.
Just called Eibach to find out what the spring rates are for the Nismo. And I'm not going to lie. The car looks good but Im going to pass on this.
The 370z is already well balanced out of the box I do not need it to induce understeer.
The stock Nismo rates are
F- 8.6 R- 9.3
The Eibach rates for the normal Z
F- 8.6 F- 9.5
The Eibach Nismo Rates are
F- 9.8kg R- 9.5 which is a 14% increase in the front and 2% increase in the rear.
I dont see why they would set this car up like this. They completely switched up the spring rate bias from front to rear. And a front heavy spring like that will not only induce understeer, but the valving range of the shock is also slightly altered, the rear rates being extremely close to stock, and then the front rates are more sprung. Even though it is within the valving range of the shocks, if Nismo really did a good job fine tuning their shocks then these springs will throw off the original feel Nismo was going for.
Just to show you the rest of the spring rates
Tein s-tech -
F- 8.5 R- 9.4
Tanabe NF
F- 5.9 R- 6.8
Tanabe GF
F- 8.8 R- 9.1
Swift Spec R
F- 10 R-10.5
So just about every spring manufacturer out there pretty much decreases the rates of our nismo which pretty much completely dtunes our upgraded shocks.
Eibach although stiffer, went in a weird direction with their spring rates, and will alter the handling characteristics of the Z
Swift is the only one by numbers is a performance option for our Nismo shocks.
these are all converted to kg/mm if you guys want me to post it up in pounds per inch I can do that later.