I was driving an 83 that I just bought, and when I took it on the freeway, it started making an odd noise in the back... almost like a thumping noise. So I took it home and my Dad and I put it up on jack stands to investigate. We thought that it was the rear diff, but that checked out fine, after spinning the tires and doing a bunch of checks we still dont know what the problem is. Anyone else have a problem similar to this, or might know what it is? ANY suggestions would be greatly appreciated.

 

rear U-joint?

 

how are the shocks? Ive seen other people post about how their car will thud with a worn out suspension.

 

Perhaps a wheel is out of balance?

 

Hmmm.... just got through a fun week of running through most of the car. None of those explanations seem to be the cause. The sound occurs when I went on the freeway at about 60, but not at low speeds. When put up on jack stands, it occured at about 5K RPMs. So it occurs only when the wheels are spinning quite quickly. It's more of a howling noise than anything...

 

howling

might be your differential

drain it and put new grease in

 

In my car it was the pinion bearing. When I lowered my car it changed the pinion angle and caused to much pressure on it and destroyed the bearing. It took alot of trial and error to find out what was causing this noise and I hope this helps you.