MatthewMiller

I think swapping over the other wheels, tires, and Konis is a very good idea.
Meh, you'd be surprised how many race cars are set up with springs that are totally unloaded at full droop. The rear of my car is the same way. It's not ideal if your car is leaving the ground (both wheels off the ground), like a off-roader, but otherwise no problem. In roll, the swaybar should keep the inside wheel loaded against the beginning of spring travel anyway, and the car just picks up that inside tire. If there is no swaybar, then the inside wheel is just left to roll along the road with no load other than its unsprung weight.

Tom400CFI

Copy that. If we get more warm weather, I may swap parts and just go drive it and see how it feels.

Tom400CFI

I took another look at the Ridetech; they're not double adjustable! They're only adjustable in rebound, just like Koni. So I guess I have to look more closely at QA1's....

Tom400CFI

Also, I wonder if there is some way to mathematically calc the EFFECT of less body weight on spring "rate". What's a 2000lb car going to behave like on a spring rate? Or what wheel rate is the car comparable to now that it's lighter?

MatthewMiller

That's correct, they are single adjustable for rebound. They unlike Koni, though, in that they are monotube shocks with Fox internals, whereas the Koni Sports are twin-tube dampers. However, Ridetech should be able to make a set of three-way or four-way (I think three-way) dampers in the same shock body. It's just that they are probably mega bucks.

To really do it right, you need to calculate not only the total weight but the new weight distribution and the new CG. In pure heave (all four wheels moving in the same direction at the same velocity), for rebound it should scale directly to the proportionate weight loss. In theory, the high-speed compression should remain similar as long as the unsprung weight didn't change (it probably didn't - wheels/tires/brakes and suspension pieces weight whatever they weigh no matter how much other stuff you remove). This is a challenge in making light cars ride well: the unsprung weight is a bigger proportion of the total mass of the car.

For pitch and roll, the effects are not just proportionate to the loss of mass, but also to the (presumably) lower CG height. The lower mass and the shorter lever arm of the reduced CG height will both lower the forces attempting to roll or pitch the vehicle. If you can get values for both changes and multiply them by each other, then you can calculate the proportionate amount of wheel rate reduction required to resist those forces the same amount as when the car was stock. The only good way I know of to measure CG height accurately is to measure the front:rear weight bias on level ground using wheels scales, and then raise the front of the car a lot (like 3-4ft) and measure the weight bias again. Applying geometry to the change in weight bias will tell you the height of the CG.

Kevova

I would shop shop for coil overs possibly used from a late model dirt or modified. Lots of parts come up for sale at the end of the season. Drivers quit, upgrade,, and change classes and sell off parts.You would just need to install upper shock mount where you need to. It's not like there's a body to be concerned about. An asphalt modified driver could help you with the set up. IMO cart is to light for stock C4 springs.

MatthewMiller

I'm going to disagree with this part. My 96 runs VBP Xtreme springs front and rear that more than twice as stiff as the base stock springs that it came with. It's not at all too stiff at ~3200lbs, not even close. Given that Tom's car is surely more than half the mass of mine, and on base spring (I think?), I'm going to guess it's still sprung lighter for its mass than my car.

Tom400CFI

Yeah, me too. IDK why people keep saying this. What do people do when they modify their suspension for better handling/performance? They increase spring rate. I've increased the effective spring rate. My car likely had base springs. It's an '89, non Z51 car.