Since the problem just appeared, I'd guess it was related to the U
joints. There may be something preventing the cups from fully seating.
The fit of these parts must be nearly perfect.
I doubt of overtightening would cause the problem.
I once got a U joint together with on of the needles out of place
between the trunion & the end cap. The snap rings went back in & I
thought all was well. But the joint was forced slightly off center.Made
a terrible vibration & noise. Pulled it apart & put the needle back
where it belonged, & all was well.
Matt Wehland wrote:
> Hello, I just replaced the ujoints in my 78 suburban (front & rear, 1
> piece shaft). I now have a noise, sounds like grinding metal from
> the rear. It is most pronounced from 10-25mph, above 25 the frequency
> becomes higher and the rest of the truck makes so much noise that I
> don't notice it. I checked the shop manual (after reinstalling the
> shaft) and noticed that it calls for around 20ft-lbs on the rear
> strap bolts (4 bolts that hold the joint to the rear axle). I had
> torqued the heck out of them. So I loosened them up, lock-tited them
> and retourqued them to a guesstimated 20-25 ft-lbs (much less than I
> had them before). I also had one of the rear bearing caps fly off of
> the shaft and roller bearings go all over while installing the
> joint, I cleaned them up real good and got them all back in place.
> Also the pinion seal has been leaking for some time now, I haven't
> even looked at it yet. The truck sat for 4-6 weeks, only driven once
> before I got around to replacing the u-joints.
> What is the best guess on what is making the noise? Did I screw up
> the u-joint by over-torqueing? Dirt in the bearings from when I
> replaced everything? Something with the pinion bearing that became
> worse after replacing the u-joints? Bad u-joint from the factory? It
> was real tight when moving by hand, but it is brand new so?
> I have no problem replacing the u-joint again if that really is the
> problems, but I'd hate to do it and then find out it was something
> else stupid.
> Thanks, Matt