[TR] Universal Joints: What is the Reason for Replacing them?

[Randall]

> WHY replace the U-joints at all?  WHAT symptom would you be trying to
> eliminate? WHY are new U-joints even necessary?

Personally, I don't replace them until they have failed.  First sign of
failure seems to vary a lot; sometimes it's just excess vibration (from a
seized joint forcing other things to flex), while more often it's excess
play in the joint.  IMO any slop whatsoever is reason for replacement and I
check at every lube job.  One of the most common symptoms is a clunk when
you start out (especially after backing up), but that can also be backlash
in the differential, etc.

Of course if you have the driveshaft out for any reason, you should also
check the U-joints for smooth motion and no play.  Last time I changed the
gearbox in the TR3A, the front U-joint felt kind of loose and 'gritty' ...
when I got it apart I discovered that it's rollers were square !  Apparently
they had been seized but the joint was moving anyway.

Another thing to look for at every lube job is any sign that the caps are
moving in the yoke.  A strip of clean spot next to the circlip is a giveaway
that there is something wrong.

Randall