vtchang

iTrader: (9)

that logic doesn't compute, but im not a suspension guru.

Oh well. . .

guitman32

iTrader: (15)

The reason why kits like the KW, Bilstein, Koni and other fixed body length systems work is because their length and piston stroke are already optimized to work in a given range of ride heights, capable via the spring perch and the length/rate of the helper spring/spring combo.

With these fixed setups in the extremes you will run out of stroke and bottom/top out prematurely (before you run out of suspension/wheel travel). But as we know the Zs geometry is optimal at a relatively high ride height anyway (aftermarket modifications aside). Which for example is why so many people go too low and complain of snap oversteer at the track.

The bump stop is a valuable tuning tool, and the reason why you want to adjust the shock body length so that you are on the stop as you run out of usable suspension geometry or the tire rubs, whichever comes first. The spring rate will obviously be a factor here, and determine how much suspension travel you need before reaching this point.

So you adjust the total shock travel via the body length with no spring and the wheel/tire in place (which represents your max compression travel), then use the spring rate, length, helper springs, etc to tune the final ride height and corner balance.

I made this to help people understand what happens when you adjust the body vs the collar, obviously to be taken in a vacuum, corner weights etc aside, and is applicable for the coilover front. For the rears since the OEM config is separate spring/damper, adjusting the shock body length only affects piston travel, not ride height.