Anyone notice any 'stumbling' or slipping of the rear diff when its cold?

Any chance the 'stumbling' you're feeling is from the DSC/traction control kicking in? I have felt that caused by a little tire slippage on cold pavement, especially with the OEM tires, but also with the winters. I've never had a car with traction control before, and the feeling and sound of it kicking in is a little suprising at first- I would probably look to the diff if I didn't know it was the DSC.

-Sean

Nope. I don't have Traction Control on my car.

What you are probably feeling is one tire loosing traction, and the "stumbling" is the limited slip differential. Most limited slip diff's are not "smooth" when they slip (one tire spinning faster than the other) - not sure if the 8's limited slip diff is like most, but could be...

Why does it do it only when it's cold? That, to me, is the mystery!

Umm, because the stock tires suck ass and they're slipping. Which is why the LSD is kickin' in.

You might be on to something! It could be part of the problem. But again, why only when its cold?? Could the tires get that much better just by warming-up? I don't think so. Besides the problem goes away fairly quickly, long before the tires would get a chance to warm up. Its usually gone in a few minutes of driving. But I will admit that the tires could be adding to the problem.

Yes. That is the reason you need to run winters or all seasons in the winter. The rubber in Summer only tires goes thru whats refered to a phase shift (?) whereas it gets rock hard at low temps and will cause the tire to loose its gripping ability. All season and winter tires have a different rubber compound designed to stay softer at colder temps thereby keeping its gripping properties intact.