2014 Chevrolet Corvette: Tire Chatter When Cold
April 15, 2014
Our long-term 2014 Chevrolet Corvette Stingray exhibits a judder when you make a tight turn (say, turning from a driveway onto a narrow street) when the car is stone cold. And it's completely normal and nothing is wrong.
I've observed this every time I've driven our C7 and it's never struck me as anything out of the ordinary. The first time our C7 did this I immediately chalked it up to a tight differential. When cold, a limited-slip differential can bind up and act like a spool (a locked diff), and the inside rear tire is forced to "skip" on the pavement. This manifests as the juddery "thunk-thunk-thunk" you get when you make a very tight turn at very slow speeds. Once warm this behavior goes away.
However, I've since observed that the car will exhibit this behavior whether power is being applied or not, clutch in or out, and seems to be at the front end rather than the rear. Plus, our C7, being a Z51, has an electronic differential, which ought to be fully open during such conditions. All of these factors suggest this is less a differential issue than it is a steering Ackermann issue.
The owner's manual offers no elaboration other than "it's normal":
Ackermann geometry pertains to the wheels doing the steering. In this case, the front wheels. In a nutshell, in true Ackermann geometry, the inside front wheel turns more sharply than the outside front wheel. This is because the inside front is closer to the center point of the turn than the outside front, and thus traverses a tighter arc.
It turns out GM built the C7 with reduced Ackermann for packaging reasons. Thus, the inside front tire skips along the pavement when subjected to a hard turn when cold. The skipping is quite pronounced and I can see where some people might think something is very wrong with their car. When the tire warms up, its carcass is better able to deform, so the skipping goes away.
Now you know.
Jason Kavanagh, Engineering Editor @ 16,673 miles