I purchased a 2017 Z06 this last weekend and on my way home it was apparent something wasn't right. Going 70ish mph on a freeway I travel daily, when the car would squat over bumps, the rear end would feel like it slightly turns right. In Tour mode and somewhat Sport mode it felt like the car was under dampened in the left rear corner. Is there anything I should be on the look out for other than a bad MR damper or out of alignment?

 

Do a search for "rear caster" and you will find much information...…..as this search will get you to most of the rear alignment threads......and all the expert opinions...….

 

thanks!, I thought I remembered reading about bump steer, but could only find stuff about C5s and C6s.

 

It sounds like you have an alignment issue. I don't see a bad shock causing the car to change direction. However, alignment or a changing alignment can do that. One of the first things to be checked is to see if one of the lower control arm cams is loose thus letting the control arm move sideways when you hit a bump. If one of your lcas is moving that affects camber, caster and toe. Yes, a bad shock may permit more and quicker up and down wheel travel but if the alignment is set right the extra travel shouldn't affect direction.

Another thing that can cause directional changes is if your toe is too far out of range. Excessive Toe In or Toe Out in the rear can cause the back end to move around as the rear wheels bounce over bumps. Say you have a lot of toe in and the left rear tire hits a bump which reduces the tires grip. The right side tire could push the rear very slightly to the left because of the excessive toe in and the car would feel like it turned right. I had this problem on my C6Z. I had a lot of rear toe in for the track so I could get more speed through a certain corner. Driving the car on my local streets that lots of bumps/potholes would cause the back end to move back and forth. Even at 35 mph the back end would move back and forth on a rough street.

Rear caster can be an issue at the limit of handling but I don't see that as causing your problem now. I ran my car on track for a year with rear caster way out of whack and didn't have any serious handling issues with it. Putt Putting down the road at 70 is nothing.

Bill

 

Thanks Bill,
the only thing that let me to believe rear shock was it felt like the drivers rear was blowing through its travel allot faster and to a greater magnitude than the passenger side. I realize i'm sitting on that side, but never had that issue on my C67. It just felt odd, like the front was perfectly damped and the entire rear was under damped or under-sprung.

I have an appointment to take the car in next week. I believe it is an alignment issue from your post and others on the side. But I will have them check over the rear end for issues, something seems off compared to the other MR cars I have.

 

Same problem I was having. My rear caster was never adjusted from the dealership so one side was positive caster and the other side was negative. This made it so over any bump the one side wanted to go one way and the other side wanted to go another. It's definitely an odd feeling and makes the car feel very unstable. I recently found someone who could do the alignment correctly (after calling 10 different dealerships and having no luck) and the difference is MASSIVE!