Hi everyone,
Well the title says a lot here. I have a 97 Z28 with automatic trans, 127,XXX miles and when I first pull out of the garage it does not make this sound but after driving awhile, like say 20 minutes at least, when I make a turn left or right I can hear some sort of rubbing or scraping type of sound. Seems to come from the rear area. My mechanic and I can duplicate the sound in the parking lot but once it's up on the lift we can not find anything wrong or out of place. So, it's something that happens on the ground under the weight of the car and it's happening during a turn and after things are warmed up, which makes me wonder about things like rear brake pads or would my tires be swelling a little but I don't see any marks from rubbing anywhere? I don't know.
Anyone have any ideas of what to look for?
Thanks! You've all been so helpful in the past, I really appreciate it.
Jeff

 

Sure sounds like an issue with your deferential. The deferential allows the rear wheels to turn at different speeds. The harder you turn the more the deferential has to work. Your Z28 has limited slip/Positive traction to prevent one tire from spinning under hard acceleration. As you can see one system allows the tire to slip and the other system tries to limits how much it slips, It is common for there to act up when hot and there is an additive you can add that may quit it down.

 

Yup posi unit going south.

 

Thanks Gorn and Y2K. Gorn can you advise what the special additive is?
Jeff

 

There's many different brands but basically it's this stuff.

 

Awesome! Thanks!

 

UPDATE!
It worked. I needed to replace my pinion seal anyway so did that and put some magic solution in and so far no noise!
Thanks again everybody.
Jeff

 

Great!