My next adventure - 80K miles and it's now making a light whining/grinding noise when I'm at speed. The sound stops when the vehicle stops. The brakes were done about 10K miles ago, and the rotors were replaced then.

I got it into a shop yesterday and they put it up on the rack and pulled the tires, said there's nothing wrong with the brakes but that when they turned one back wheel while it was up on the rack, the other turned in the same direction rather than in the opposite direction, as it should with the limited slip differential (G80 option code). The mechanic also said that the gear oil in the rear end is cloudy/dirty, which is likely from the limited slip clutch plates grinding themselves away. This is not a job this shop will be able to do, so it looks like I'm going back to the dealer for this.

What can I expect to pay to have the LSD rebuilt? Is it likely that the noise I've been hearing is a result of this problem? Is it safe to drive my 'Hoe until I can get it into the dealer (Tuesday)? Thanks.

 

The G80 is a locking diff., not limited slip. That's why they turn in the same direction.

Does the noise occur during acceleration, cruising, and coasting? Also in Drive and in Neutral? During braking?

 

Thanks.

Yes, the noise occurs during acceleration above about 20mph --or maybe that's just when it becomes loud enough to notice-- during cruising and coasting, in drive and while braking. I'll have to play around with it in a parking lot a little to find out about neutral.

 

Have you checked the rear brake pads? There's a scraper that makes a noise when you apply the brakes when they get worn down.

 

g80s also don't have clutches

my first step would be to jack up the rear tires and spin them by hand, could be something as simple as a bent dust shield

 

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I’m sorry you are experiencing this issue with your vehicle. I have checked my resources, but do not see any known issues as you’ve described. Please keep us posted of the results of your dealer visit.

If you have additional questions, please feel free to contact me privately.

Louis
GM Customer Service

 

It's at Stutzman Chevrolet in Winchester, VA right now, and they found steel shavings and cloudy gear oil after taking the rear cover off the diff. We'll see where this goes.

 

It was the bearings: axle, pinion and carrier. $1230 all in.

Louis @ GM Customer Service: the service department at Jim Stutzman Cadillac Chevrolet produced a great outcome, with the worrying noise gone. It's never a good day when a little noise turns into $1230.00 out the door, but I feel much better now out on the road in my Tahoe.