I was due to take my TR250 to the beach tomorrow, about a 3 1/2 hour drive, but
I was concerned about the continuing vibration I had at higher speeds and when
I eased off of the accelerator to only slight pressure. Several opinions were
given that attributed the problem to a bad u-joint in my prop shaft. I was
hesitant to accept this since all u-joints had been replaced at 3200 miles ago.
I finally gave in, found a u-joint at a local auto parts store, and began
pulling the prop shaft out of the car. Of course, in order to do this, I had
to wrestle with removing the back 2/3 of the exhaust, manually remove 16 flange
bolts and nyloc nuts, and use the jack to lower the diff. When removing the
9/16 nyloc nuts holding up the diff, I found what is certainly part, if not the
entire cause, of the problem. The back left diff rubber/metal sleeve mount had
separated. The metal ring was still bolted to the diff and the rubber part was
still around the metal sleeve attached to the rear mounting bolt, but the ring
and the rubber were separated. The noises I heard and the vibrations I felt
make sense now. Under hard acceleration, the diff torqued hard enough to not
allow any vibration and when coasting, there was no pressure there to cause
vibration. When I eased off the accelerator, but still had light pressure, the
vibration was at its highest level. When I reached 65 mph and higher, there
wasn't enough torque to stop the vibration and it all came through.
Unfortunately, I'll have to take the not-as-fun-to-drive Grand Cherokee to the
beach nown as I wait for a replacement part to arrive from Moss. I found the
receipt for the part from 8/27/02. I would call this defective and expect
cooperation from Moss to replace the part without a problem.
The U joints in the diff seem fine with free movement without slop or
tightness. Please let me know if you think I solved my mystery and if anyone
else has had problems with the rear diff mounting rubber.
Andy
CD6521L
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