Ok heres the deal.....

The Z is going great from the factory, at about 8000 miles notice the rear tires are wearing almost bald on the outside while the middle & inner still has plenty of tread left. So I take it to the dealer and have them do a four wheel alignment. The alignment is off so the fix it and here is where the problem starts.

Before the alignment the car tracked straight and true, now she veers to the left slighty at freeway speeds and veers hard to the left under hard acceleration at freeway speeds. As soon as I let off the gas she goes back to going nearly straight, which requires and additional steering input. So I take it back to the dealer and tell them they did something wrong before now it feels less stable and harder to control under hard accelelation (80 to 120 MPH), well they check it again and make a couple of minor adjustments. Well guess what it is still doing it, the exact same thing. The dealer says they can't help me because the settings are within specs.


Does anybody else have a problem with the car veering to the left under hard acceleration at freeway speeds?

What do I do now, I will give you all the specs as they are right now and please tell me how to get her to track straight and not veer under acceleration.


Thanks all.

Alignment specs......

Left Front: Camber -.7; Caster 6.4; Toe 0,05
Right Front: Camber -.7; Caster 6.4; Toe 0,04
FRONT: Cross Camber: -0.0; ross Caster 0.0; Total Toe 0,09

Left Rear: Camber -.06; Toe 0,00
Right Rear: Camber -.05; Toe 0,01
REAR: Total Toe 0,01; Thrust Angle -0.01

 

Your alignment looks good. Different tire wear rates side to side can cause the thrust problem you report. Try swapping the rear tires from side to side and see what happens. While the tires are off measure and record their circumference with a tape measure. If they're an inch or more different that could cause enough side to side differential thrust to make the car pull under power.

The ultimate solution would be a fresh set of rear tires. I would attempt to get a partial reimbursement from GM because the bad alignment caused excessive tire wear.

Duke

 

Generally the spex look right, however, the rear camber is inadequate for track workouts. I'm running -1 deg front, -.8 deg rear on a car set at the bottom of the height adjusters. In your case, the rear camber is not going to be enough to keep the tires from wearing the outside edges under track conditions. Front toe is also a little high, try .02 or .03 pos (toe in), and, the rear toe could be bumped up a ahir, say to .015 or .02.

We also added a touch of cross camber of .035 which makes the car track straight even if the road has a crown to it.

The way mine is set up it tracks straight, even on roads with a little crown to them. It also grips like gum to a shoe (on the F1's.)

Alignment work is kind of a trick. Hunt down where the racers in your area go. I've found that 80% of the alignment shops around today, including dealers, really don't know what they are doing, and have no idea how to correct for a problem. The factory spex are rediculuously liberal. A car set up at the edge of the spec limits would handle like crap, so "being within spec" is just not good enough.

Hope this is of some help.

:cheers:

 

I had the exact same problem wear on the outside - Thanks to the selling dealers' alignment. I took my car to my trusted regular tire guy and he found too much toe in. Too late for the rear tires. Don't take the within specs line of reasoning at face value. I beleive most alignment machines are off. Recommend you get two free alignment checks from other shops and confront the dealer. If the dealer doesnt regularly have his alignment machine checked he should pay up. Think of all the other cars leaving the shop???