md6380

I have an autocross tomorrow and I want to play with the rake to get the rear lower or front higher to help calm the rear. The balance is currently good mid corner and I can steer w/ the throttle, but I want to see if I can calm the rear twitchiness in the fast transitions. Unfortunately I won't have time to get an alignment. In this case, is it better to raise the front or lower the rear? How does the alignment in the front and rear change with ride height changes? I know there's more negative camber with decreased ride height, but I want to make sure I understand the rest.

Here's the current car setup:
2003 AP1
Ohlins DFV, off the shelf 10/8 springs, newer suggested settings (preload 2mm front/9mm rear, height, etc.)
Stock sways
Staggered 225/255 Kumho PS91 (same class as PSS)

Stock rake is about 0.5" lower in the front compared to the rear. I have it setup for the Ohlins suggested height which is suppose to be ~1" lower all around. Center wheel to fender measurements are about 13.25" front/13.5" rear (don't compare mine to yours as my fenders have been rolled and possibly a bit flared, so may not be comparable to others).

I want to do this to see if the rear twitchiness calms down a bit in fast transitions. Also, I was previously running the older suggested 2 mm rear preload settings and switched to the new recommended 9 mm preload setting. That gave me more shock compression travel in the rear and less droop. At the last autocross I was getting faster and found a low speed decreasing radius turn where I'm starting to get inside rear wheel lift, which opened the diff and killed my drive out. I want to see if a few turns of ride height change will help these 2 issues since it's free. Also, for those of you that have played with rake, how much change starts to make a difference, 1 mm, 10 mm, more? Any info would be greatly appreciated. Thanks!

lookstoomuch

Where you are measuring rake to come up with the 1/2"?

md6380

Stock ride height measurement from center wheel to fender is about 14.25" F and 14.75" R, which is a 0.5" difference. Here's a thread that discusses how some people change the rake to change handling.

https://www.s2ki.com/forums/s2000-ra...ussion-938017/

Bruunz

So i'm about to go the opposite direction for track use. I'm planning to go neutral by raising the rear closer to 13.5 inches.

My current setup on PSS9s. Front fenders have been reshaped so measurement is not 100%.

Front Right Hub to Fender = 34.5cm / 13" 3/5 inches
Front Left Hub to Fender = 34.5cm / 13" 3/5 inches
Rear Right Hub to Fender = 32.5cm / 12" 4/5 inches
Rear Right Hub to Fender = 32.5cm / 12" 4/5 inches

However i won't have an event to go to for some time. So i wont be able to provide feedback anytime soon.

thomsbrain

If you're getting rear wheel lift, I'd disconnect the rear sway bar and see if it goes away. If it does and the rear hooks up, chances are you don't have a droop-limited problem, you just have too much rear bar for the amount of rear spring you have. Or rather, you do have a droop-limited problem but it's the bar that's lifting the wheel rather than the shock itself running out of droop.

If the wheel still lifts with no bar, then your options are to set up the rear with more droop, play with the rake, or increase front spring/bar stiffness.