Originally Posted by thomsbrain

Don't assume that the cars are "oversteery" simply because they have stiffer rear springs than fronts. Springs are just one part of the tuning package.

They set up with the rear springs stiffer because they are tuning their suspension based on staggered ride frequencies (a function of wheel rate, target speeds, and motion ratios), which is the way you are supposed to do it. If you want maximum grip from a car with little to no aero (including any street car, even an S2000 with track aero), you start with stiffer rear ride frequency and tune everything else around that to achieve the desired handling balance.

The stiffer front springs you see on common off-the-shelf coilovers sold in the US are side effects of an attempt to add stability to the handling balance without changing anything else about the car (bars, tires, geometry, aero). That's a back-asswards approach to grip, but coilover manufacturers have to go with the assumption that you aren't smart enough to tune the rest of your car to achieve the desired balance. So they just play it really safe and push the car more towards understeer, even though that approach leaves grip on the table. Then on the forums, everyone goes "the car feels more stable now with these new coilovers," so everyone incorrectly assumes that means it's the fastest setup. You have to understand that the stock sway bars are sized the way they are because the stock suspension is too soft (grip is compromised for comfort), and they are forced to use big sway bars at both corners to keep the roll in check, instead of simply using them as fine adjustments for handling balance. The issue is further complicated by the autocross people, who prize transitional response over steady-state grip, and therefore do all kinds of weird shit with their spring rates and sway bars that aren't ideal for a track car.

Fat Cat Motorsports is one of the few coilover companies marketing in the US that's willing to shoot straight on this topic and deliver the "bad news" that tuning for grip means rethinking the order in which you make changes and rethinking the role of the sway bar from a stock street car (roll control) to a race car (small adjustments to balance). They sell suspension packages complete with appropriate sway bars so that they can use the correct spring rate staggers. I've never used their products but they are respected in the Miata world. Also check out the Autocross to Win book and website for additional info on how to tune a suspension for grip. This was also the approach to suspension used by Gordon Murray for the McLaren F1.

As for me, I built a spreadsheet, targeted my frequencies based on desired speed for flat ride syncing, and had my Ohlins rear shocks custom-valved so that I could run the appropriate stiffer rear springs than the fronts. Then I fine tuned the handling balance with an adjustable front sway (no rear sway needed at all) and I've never once questioned the decision.

Originally Posted by Chuck S

"most of the US running a square tire setup" ?? Where do you get this idea from? Or am I misreading this?

Oversteer is slower around any set of curves, racetrack or street. Drifting -- oversteer carried to a stupid extreme -- is much slower.

-- Chuck

Originally Posted by Chibo

I'd be curious to see your spreadsheet. I also worked mine out in a spreadsheet and found the balance falls into line as a little more front biased than the stock CR, even though I've got a pretty decent spring rate stagger and a big front bar / softer than stock rear bar.
Of course, I'd also be glad to have you drive my car and get your input if we somehow ended up at the same trackday in California

I also fell into the FCM stuff some time ago when working through my E46 setup.

Either way, it appears there are multiple approaches which do work in the real world.