Hi, I need some input here. My car has been somewhat "loose" "unstable" or maybe tramlining on freeway speed 70-80mph. No shakes or vibrations but car will swing left and right, enough for the wife to speak up. It felt like the very beginning of loosing grip of rear end on slower speed. It is noticeable on some freeways, while some other freeway was ok. I have two other cars, both FWD, they don't have this much movement compared to the s2k on the same freeway.

Car info:
2007 AP2 53000 miles
Stock shocks and springs
Front CR lip
New rear S-04 tires in 255 (1000 miles)
Front Re760 tires in 215 (5 yrs old but decent tread, no cracking)
Cold PSI on tires set to 32
Front has S2X / ASM style 4 point tower bar
Recent alignment: http://imgur.com/XvAeXu0

Thanks!

 

First suspect is mis-matched tires. Mismatched sidewall stiffness probably. Even matched tires are subject to this is the pressures are off side to side.

-- Chuck

 

Add a trace of toe-in to the front, not toe-out (car is currently toed out)

 

I thought positive toe was toe in? Maybe the tech left an adjuster loose in the rear.

 

It is.. Current measurements are -1/32" on the paper (front)

 

Thanks guys! Just to confirm, a negative toe number means toe out?

Edit: I wikied, negative = toe out. I will try to get another alignment and see how it goes.

 

Toe out at the front isn't going to make your car tram line, front toe won't affect handling near as much as rear toe. Unless I'm completely stupid at reading you have 1/8" toe in at the rear, which is fine. Before I replaced all the bushings on my suspension I'd end up with half a degree of toe out in the front. The rear would hold, I never noticed other than crazy toe wear up front.

But I would always have the symptoms you describe when as a rookie I'd leave an eccentric adjuster loose.

 

Do you notice it happening on grooved roads and not on ungrooved? I've found that a combination of newer tires with full tread and grooved roads will make the car feel like it's moving around even when the steering wheel is held straight. A little front toe will help some, but there's not much else you can do.

 

Any amount of negative front toe will make the car hunt left and right. Even though it's not extreme, it's there.

Set the front toe to +.04 each side, for a a total +.08 toe-in and see how it feels.

 

Subframe rigid collars made this really go away for me. It is really bad when my rear tires are new, I think it is riding on the edges of the tires before they wear in to the road.