C6 making weird sounds at low RPM
 

So I just picked up a 2012 M6 with 28k on the clock. It is warrantied until 2022. It just started making a strange sound that can best be described as a "scraping" noise. It sounds almost like the tires are rubbing the fender or the air dam is rubbing the ground. This noise appears primarily in first gear from about 0-3k RPM, disappearing as soon as I get on the gas or clutch. I was able to replicate the noise in 2nd and 3rd at low speed in the same RPM range. I had a "master corvette tech" take it out but he said he did not hear anything abnormal. Either way, it's driving me nuts. Anyone know what it could be and where I could start looking? It seems to be coming from the engine bay direction/behind the dash while I'm sitting in the car.

The tech told me it was most likely either the clutches in the rear diff engaging, but this noise appears while I'm going in a straight line. He also told me it could have been from the car sitting and that it might go away as I drive it.

Commom

Sounds like you might have summer tires scuffing on cool pavement...can sound scary at first...

I’ve been daily driving my C5 for years and I never heard anything that sounded like this.

I would check for a vacuum leak, mainly at the power brake booster, but any hose fittings and check those hoses for cracks, but it makes some sense since when you step on the gas, there is less vacuum available and the leak would subside.

Why would it not happen when the car is in neutral then?

Different engine speeds and throttle plate positions can vary the pitch of the sound. Vacuum leaks can also be heard from inside the car with regards to the HVAC mode motors, something else to consider. It must be a low noise that your hearing and the "Vette Tech" can not. And again, just putting the idea out there for something to kept in mind.

That WOULD explain why the sound appears to be coming from the front vents and not the rear diff. Huh!