All,
I have an '82 Scrambler with the original AMC 20, 3.73 rear differential but with one-piece axles. About 1000 miles ago during a long road trip, I started hearing a rhythmic rubbing noise coming from the rear end when I was coasted through parking lots. The rhythm of the noise was directly proportional to the Jeep's speed. I isolated the noise to the rear differential by removing the rear drive shaft. The noise only occurs when I coast forward, not backward. Also, I do not hear the noise when the differential is being driven by the drive shaft rather than the wheels (although it's possible that the engine noise is masking it - the noise isn't that loud).
The noise hasn't gotten significantly worse since I first noticed it, but neither has it gone away.
The rear wheel bearings were re-packed 18 months ago and the differential fluid changed at the same time. I see no obvious evidence of differential fluid washing out the wheel bearings' grease, but I haven't taken it apart yet.
Any hints on what this might be? If it needs a re-build, how soon will this become a serious problem? Or is it something that can be fixed by simply replacing a bearing?
Thanks in advance.