Archived HELP! High pitch cyclic grinding in rear end

[Henry]

I was dropping off a camper for a friend yesterday and my '99 2500 started making a very loud, cyclic metal on metal rubbing or grinding noise. The noise is rotational and sounds like the metal on metal contact is occuring at a certain point on the rotarion of the drive shaft, drums or rear diff. If I accelerate slowly, I do not get the noise. I only get it under normal or rapid acceleration. My initial suspicion was that it wasn't the rear differantial because the noise is too high pitched and hollow sounding. That leaves the drive shaft or drums. I applied the brakes under acceleration and still got the noise, so I'm less inclined to believe it is a drum / brake issue, but I can't find a problem in the driveline and I've never had a bad u-joint make anything but a popping noise. There is some slop in the driveline support bushing. Would this be a likely culprit? I'd sure appreciate some input if this sounds falimilar to anyone. Thanks in advance! #@$%!

 

[DCreed]

dry u-joint bearing

 

[Henry]

You were right DCreed

You were right. I looked closer and could see that one of the u-joint caps looked sketchy at the diff. I took the drive shaft off and found that there were "NO" needle bearings in the one cup. It was wasted. The other three sides of the joint were fine. Must have just been a bad joint. Thanks for your help. You also helped me recently when my hose clamp to my intercooler popped off. Thanks for sharing your knowledge, it is much appreciated!!!!!!Oo.