I have a new 2017 stingray with a Z51 package. I was told by the dealership service manufacturer that the multiple thumping sounds my car makes when cold and first driven are the result positraction ( I know it is not called that now) warming up and it is normal.I drove a dealer car like mine sthaty was on their showroom floor and it did make the same noise.They said that is normal and the vibration and sound goes away when it is warmed up and don't worry about it.Is that correct?

 

If you are talking about thumping / skipping noise from the front with the wheels turned sharply - that is normal due to sticky tires and suspension geometry. The noise is less with warm tires. Less sticky tires like the Michelin all seasons don't make as much noise. I have not had any noise from the rear of my 2014 Z51.

From 2017 manual:

Tire Chatter/Hop
When driving at slow speeds and in
very tight turns, the vehicle may
have tire chatter/hop. This condition
is normal and the vehicle does not
require service.

Ron

 

It's normal to hear/feel the thumping. I was really glad someone had told me about it - the first time I heard it, it scared the sh*t out of me... Shouldn't be from the rear end. I would actually be a little more worried that the dealer didn't know about it, as Ron pointed out it's in the manual.

Jim

 

Apparently the guy doesn't know what he is talking about. If it's from the rear center piece they should have recommended a fluid change. At least that was the way it was with the previous generations.

My base car even skips (different tires from the Z51 cars) across painted lines in parking lots when I'm turning. And, the Z51 cars will skip when turning regardless of the pavement until the tires warm.

 

OP, do you have the M7 or A8 automatic? Seems like you're not asking about tire chatter, you're asking about cold start and rear end clunk? Am I right?

 

Yep, getting colder. The C7 Chatter or Hopping as GM calls it is/will be an issue.

It is caused by low slip angle of the race car type tire construction of the Michelin tires! This is a PDF with the tech details if interested: http://netwelding.com/Wheel_Chatter.pdf

This is what DOESN'T cause it:
Sticky tires-in fact it is the opposite - the hard, slippery tire tread when the tires are cold is what makes it worse!

GM says it is worse when wet, when traction is lower-I have validated. The PDF discusses why.

The Ackerman Steering geometry. In fact, it is the lack of full Ackerman steering that is the cause! There is good reason why full compensation for the different turning radius of the front tires on a sharp turn is not employed. Details with pics in PDF.

Of interest, it goes away (or mostly depending on the tire) with more normal slip angle all season tires with the same steering geometry. All season and winter tires tread also stay more flexible when cold.

SOLUTION:
GM's "it's normal" statement doesn't make me feel better when making a sharp turn after backing out of the garage to go own my driveway. When it is 40/45 F or colder it is so bad I just don't turn as sharp and make a "K" turn! Sometimes do it twice. Doesn't do any harm but don't like the front end "hopping!"

If you have a friend it the car and backing out of a parking slot when it's cold-be sure to make a "K" turn. If you don't, they are sure to tell your friends you bought a piece of junk-it feels that bad!

Been following this since I got my September 2013 built Z51. It was much worse than my C6 Z51 and little info from GM. No little tag as I got on my current Grand Sport. When I am making "K" turns in the winter I thnk of that 1+ 'g' turn I can make in warmer weather!



Low Tire Slip Angle of the Race Car Type Tire Construction of the C7 Michelin's Cause Chatter When Cold