Help me sort out my suspension woes!

[T-RexRacer]

But if you put too stiff of springs on for the car, then you don't get the benefit of the engineering that went into the rear suspension. If the rates are too high all of suspension deflection starts to transfer to the sidewall of the tires and the rubber bushings.
Now YOUR spring rates may not be so high that you are seeing that. But a rule of thumb in racing, and it is counter-intuitive, is go as soft as you can get away with. It's not as critical on the front because the McPherson strut has it's own limitations. But if you go too stiff on the front and soft on the rear, the car isn't balanced and in this case you would get understeer. Take it for what it's worth.

[McCoy]

Originally Posted by T-RexRacer

But if you put too stiff of springs on for the car, then you don't get the benefit of the engineering that went into the rear suspension.

I thought the engineering that went into the rear suspension was not the best, but that's just my opinion.

If the rates are too high all of suspension deflection starts to transfer to the sidewall of the tires and the rubber bushings.

Agreed, that there is going to be more deflection in the bushings and tire, but I don't think it's as bad as people point out. As long as the damper is valved for the spring rates then it's a matter of tuning the rates F/R to get the best handling characturistics.

Some of the fastest IT guys with B13 chassis's(Greg Amy is a perfect example) are well above 1000lb spring rates with custom valved Koni's that can work with these stiffer springs. Just 5 years ago this was thought to be the wrong way to go for many of the reasons that you just mentioned and that 550-600lbs springs were the limit, even with a full cage. Just food for thought...

[T-RexRacer]

Originally Posted by McCoy

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Some of the fastest IT guys with B13 chassis's(Greg Amy is a perfect example) are well above 1000lb spring rates with custom valved Koni's that can work with these stiffer springs. Just 5 years ago this was thought to be the wrong way to go for many of the reasons that you just mentioned and that 550-600lbs springs were the limit, even with a full cage. Just food for thought...

True to some degree, Greg's NX2000 has a totally different suspension. But I would agree you are seeing much higher spring rates on racecars these days.