Hello all. I have about 5k miles on my 2006 Z51 MN6. I am about to take it to someone to check the alignment. Here in Alaska the studded snow tires wear grooves in every road, some more, some less. My baby wants to “climb out” of these grooves big time.

For example, if I am just left of a pair of grooves ( say 1” deep by 24” wide) and I’m moving gradually to the right she hesitates just a little before falling into the grooves, then if I continue moving right she will suddenly jump right and climb out. What is interesting is that the effect is magnified about three times when my right foot gets heavy. This is really disconcerting when passing a car, as in pulling into the opposite lane grooves with heavy aceleraton and then changing lanes back again. She will actually jump two feet left or right when crossing the grooves. Not a good thing.

So I did another test. At highway speed where there were some shallow grooves I was going straight with tires about 6-12” left of the groove centers and romped on it. The cars jumps left. Then I tried 6-12” right of center, and she jumps right.

So here is my question. What changes during acceleration? Does the rear alignment change just a bit? I’m trying to gain a little knowledge before I talk to my alignment guy. And if anyone knows what alignment spec is suspect that would also be appreciated.

Bruce

 

I don't think you have an wheel alignment problem.

The wide tires cause the car to try to follow a groove. One of the disadvantages of an excellent smooth road handling and suspension design.

 

welcome to the I drive a Z51 on bumpy uneven roads club......

 

 

A set of skinny studded snow tires will solve that and a 4x4 sticker under the Z-51 Badge.

 

Well, I finally took my Z51 to the dealer and they say all alignment is per specs. What is interesting is that since I started this thread I drove an identical car and, while it also acts similarly, it does not dart sideways anywhere near the same amount. I’ll start looking for a good alignment shop.

 

Front and rear alignment both change significantly with acceleration (or braking, or cornering).

Factory alignment specs allow for a wide tolerance, so just being "in spec" doesn't mean much. Get it aligned to the exact center of the tolerance band and see how it drives. Also, worn or improperly inflated tires could be part of your problem. Are you lowered at all?

 

When your right foot gets heavy the rear toe changes, that is why some of us align the car differently than spec. Their is also an issue which has been described as side stepping....kind of a characteristic of our suspension....very noticeable on rough uneven pavement when accelerating & turning.

 

Take the run flats off and you won"t have this problem. That's what I did, now the car handles like it should have when it came from the factory

 

My C5 had bad bump steer, fixed with Firestone runflats.
My C6 had a wander at speed, fixed with FS RF tires.