993944S2

Hi.. I have an 86 Turbo. 131K miles. Last week I drove it for 4 sessions at a driver education. I was gentle. Street tires, pads etc. Nothing crazy. Drove home for an hour and all good.

Today I took it out and after about 5 minutes I start hearing a thumping noise from the rear end. If I accelerate it disappears. If I hit the brakes fairly hard it also seems to go away. Under steady state throttle its bad, and seems to be getting worse. It sounds like it is in time with the the speed of the tires. My rear axles all seem fine. Nothing else seems obvious. I did have some pinion whine prior to this but it was really not bad. Is there any way to diagnose? Thanks in advance for any comments.

Don

thomasmryan

Hitting the brakes may be stabilizing a bad wheel bearing. Jack her up and see if you can recreate the noise and check for slop in the CVs or carrier bearings.

Another recent post had similar complaints and the axle stub nut was loose.

Jason @ Paragon Products

I'd bet wheel bearing as well.

993944S2

Do wheel bearing go from no noise at all to shot that quickly? In the past I was able to hear them start failing.

mytrplseven

After tracking the car at a DE, you can expect wheel bearings to fail quicker due to torsion and side loads. It's an unfortunate part of having fun with sports cars. Drive 'em like you stole them and things will wear out and cost you. My prospective son-in-law is playing with his Nissan GTR and now brakes and suspension parts are starting to cost him.

harveyf

The exhaust system hitting on the body can make a thumping noise too. You may have broken or detached one of the exhaust hangers. There are rubber hangers at the rear near the muffler that are easy to see and also hangers in the tunnel area which are harder to see. The exhaust on my silver car will thump on the center tunnel since I didn't take the time to hook up the tunnel hangers!

Wheel bearings are going to "whine" as they fail. Fortunately I don't have much experience with ring and pinion but I expect they should whine also. Or sound like a pretty severe grinding noise, like you've got gravel in there!

The CV joints on the rear half shafts could make a thumping noise. It will be constant (tap, tap, tap, tap) but speed dependant, is more likely to occur while cornering and in only one direction of cornering depending on the side.

Go out on a clear road and make do some pretty firm S curves back and forth. Listen for differences in a left turn vs a right turn. Also try it with some acceleration present, while coasting, and while deaccelerating.

You may want to have someone else drive and you sit in the back seats. Noises are tricky. I've even gone to far as to hook up rubber hoses that run from the drivers seat to various locations that I can use as a remote listening device.