Rear end makes making noise when hot

[Binksman]

I have a 94 Trans Am and the wife pointed out a new problem with the 'bird the other night. We took a trip of about 30 miles all highway and interstate, and when we go to our destination she noticed a clunking noise she thought was from the front. I stood in the parking lot and determined it was coming from the rear end. By the time we got it back home, the noise from the rear end was louder and more evident. I had her pull in and out of the driveway a couple time and noticed the noise sounds like the tires are rubbing the frame and it seems to make the noise most while turning.

I got underneath with a flashlight and checked around the tires and wheels, but didn't see any signs of rubbing or scraping on the wheels and tires or on the surrounding components (I just painted everything while putting new bushings in). All the bolts are still tight, and you can't feel a difference while driving the vehicle to indicate the rear end or brakes are locking up.

Any ideas?

[soCalTA]

have you changed the diff fluid lately or at all?

[fastTa]

Super hard to diagnose with hearing it in person. But, you could start narrowing things down by:

1. Check the differential fluid level and look for signs of leaking.

2. Look for any excessive wear signs on the rear discs.

3. Look to make sure the tires aren't rubbing the jounce bumper or LCA's ( not sure how wide your tires are) - I wouldn't think this would be it from your "clunking" description.

4. Could be a wheel bearing front or back.

5. Check your tranny mount and or torque arm bracket to make sure they are still good and the bolts are all tight.

6. Check your LCA bolts.

7. Check your shock bolts.

Any way you can post a sound clip?

[Dave Vince]

Friction Modifier

If it is a clicking or scraping sound coming from the rear when making turns only. Change your rear end fluid, and add Friction Modifier. Available at your GM dealer. This should clear the the noises the Posi clutch's are making when turning.

[braindeadracefan]

Sounds like what those guys said... change diff fluid and add friction modifier. I had a noise like what you're describing and that cleared it right up.

[Binksman]

I haven't touched the fluid in the rear since i got this car in March. I've been too busy fixing the rest of the car. I'll take the cover off later this week and change that for what is probably the first time in 124k miles.

We've been driving it on short trips around town since the other night and it hasn't made any noises yet. It seems to only do it after it gets heated up on the highway.