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

[Will Daehler]

I've been reading about all the tips for replacing the universal joints on
the drive shafts.  It's been five minutes, and I'm still not done. It's
actually been almost a month since Christmas, yes Santa left me a pair in my
stocking. Hardy Spicers. That U-tube video, what an inspiration!

What has been curiously lacking with the discussion on the list so far is:
WHY replace the U-joints at all?  WHAT symptom would you be trying to
eliminate? WHY are new U-joints even necessary?

Last year I replaced my drive shaft with another one that I had won on
E-Bay.  I had been driving around in my TR4, with my right leg pressed hard
against the transmission tunnel cover.  And every once in a while there was
a thump, and a bump against my leg.  My conjecture was that it was worn
universal joints, and this flexibility was allowing some part of the drive
shaft to be so far out of position that it was grazing the tunnel cover
occasionally.  So when I replaced the clutch last May (thanks MOTRAH) I put
in the replacement driveshaft.  All problems cured, but I'm just wrenching
in the dark.

Will
In Wisconsin