2003 Yukon clunking from rear when both tires off the ground

[Pete315]

I changed the rotors and rear brake pads 2 weeks ago. I had a scraping and squeal from left rear brake. I took everything apart and discovered one of the new rotors I got was severely warped. The rotor was actually hitting the bracket the caliper attaches to. Autoparts store replaced the rotor. Before I put tire on and truck still on jackstands, I put the car in drive in 2wd mode and the rear was making an awful clunking noise while the tires were spinning. Could that be the locker engaging and disengaging? When driving on road, the rear makes absolutely no noise at all.

 

[justirv]

I changed the rotors and rear brake pads 2 weeks ago. I had a scraping and squeal from left rear brake. I took everything apart and discovered one of the new rotors I got was severely warped. The rotor was actually hitting the bracket the caliper attaches to. Autoparts store replaced the rotor. Before I put tire on and truck still on jackstands, I put the car in drive in 2wd mode and the rear was making an awful clunking noise while the tires were spinning. Could that be the locker engaging and disengaging? When driving on road, the rear makes absolutely no noise at all.

Having a locker (RPO Code G80?) was my first thought. I believe it needs some tension on one or both wheels, else it really can't figure out what to do. It's a mechanical mechanism which senses tire/wheel unloading to engage. Doing a diff service while your there is not a bad idea, if you have no history or it's been awhile. Make sure you use the specified fluid.

 

[rockola1971]

That "noise" is your limited slip locking diff being totally confused on what to do. Raising it up weight of wheels and running it like that for extended periods of time will end in your clutches in the Diff getting burned up.