Jason Saini

I fully agree with some of your points, Rev... but I wanted to clear one thing up. Just because a car is near 50/50 doesn't mean you tune it by matching spring rates. Spring rates have less to do with weight distribution than they do with suspension design and the dynamic behavior of the car as a whole.

Example... I used to race FWD, usually having 60/40 distribution. By your logic, one would run stiffer front springs. It is widely recongnized by the fastest race teams that much higher *rear* spring rates are the way to go. How stiff depends on the stiffness of the chassis, the dynamics of the car in stock form, etc.

In the S2000, you definitely want stiffer front than rear wheel rates. The split in stiffness is unknown (much testing would be needed) but another good example I can throw out was Peter Cunninghams's Realtime NSX. They were at 1400lb front springs and 300lb rear springs with no rear sway bar!!! That was to get the balance that they wanted.

I don't have a single guess as to where good wheel rates would be for the S2000... maybe I'll call Scott with King and talk it over. If I find anything out I'll post it here.

Luis

[QUOTE]Originally posted by The Reverend
[B]Teins are height, dampening, and rebound adjustable.

Luis

Actually, all of the shock systems I had a look at have higher spring rates at the back than at the front with the exception of Spoon and Bilstein. This includes Mugen and stock springs.

The Reverend

Suspension settings 101:

Spring rates:
Stiffer front rates lead to more oversteer
Stiffer rear rates lead to more understeer

Note: higher tire pressure has same effect has higher spring rate, provided you are not over or under inflating to the extent that the contact patch is becoming too small.

Shock dampening:
Stiffer front shocks lead to more understeer
Stiffer rear shocks lead to more oversteer

Sway bars:
Thicker front bar leads to more understeer
Thicker rear bar leads to more oversteer.


As for setting up the S2000, something like 350 front 420 rear should be fairly neutral and not TOO stiff. But what you would want for your own setup is something you have to figure out for yourself.

As for setting up a FWD car (since someone brought it up), the common solution to understeer is to use REALLY high rear spring rates and REALLY high rear tire pressures. The reason this works is simple - any time you throw a setting WAY into the extreme, you are going to see negative effects. By setting the spring rates and tire pressures so high, you make the rear end bouncy to the extreme that it just doesn't want to sit on the ground anymore. Also, the tire contact patch becomes very thin from overinflation. On my Integra, I used a 19mm Integra Type R rear sway bar and LOWER rear tire pressures to create a very neutral, fun, FWD car. In fact, if anything, it was a bit too tail happy - but I kept it that way since it was just too much fun. I used to run about 36-37 psi in the front tires and about 24-25 psi in the rear tires. It accomplishes the same effect - making the car neutral, but without making it bouncy and unstable like very high spring rates do.

cdelena

It is my understanding that RWD cars respond exactly the opposite of this.

Jason Saini

[QUOTE]
Spring rates:

The Reverend

I agree completely - these are very general guidelines and individual cases nearly always have individual characteristics. I just posted them to give people a general idea of what to look for.

As for the ideal setup - one reason it always remains unobtainable is that as we change one aspect of the car's performance (engine, drivetrain, brakes, whatever) the way we need the suspension to compliment the car also changes... Not to mention the fact that our own preferences as drivers change all the time.

cdelena

The updated King site shows some different spring rates for the N-O coilovers. This is consistent with some others we have seen and seems that it would further reduce oversteer. Very expensive units at $3300 but high quality and fully adjustable. Worth it?

Spring Rate [in/lbs]
MUGEN___ Stock
F 570_____ 200
R 370_____ 275

rocketman

I would appreciate some enlightenment on this whole issue of changing the suspension. It would seem that:

1. unless you know what characteristics you want and know what you are doing, and

2. either have the equipment yourself or know somebody else that knows what they are doing and you trust

one would be better off not messing with the stock suspension. I don't know what the heck I am doing with regard to suspension, but if I threw some $$$ at a shop or dealer and said "make it handle better", I could be very pleased with the "new" handling or end up with poorer handling (ie, a crap shoot).

Is this a reasonable assumption?

Luis

To be precise I'd say that springs, dampers and swaybars do not affect weight transfer. Weight transfer is simply a function of acceleration and deceleration. What they do is affect how the car reacts to weight transfer, ie. how much it rolls, pitches or lurches, which is something different.

I agree that we are entering professional racing here. I can't begin to imagine how an amateur would benefit from say a 4-way adjustable shock, without a full blown supporting setup and organization.