Stuart:
There are several ways that u-joints can fail prematurely.
Installation problems are an obvious one. When installing them
the needle bearings can fall into the bottom of the cup which may go
unnoticed - and the u joint will not last long with displaced bearings.
Another way they can fail is if they are used to transmit high
loads that are not purely torsional and coaxial. So if your suspension
is collapsed or sagging in a big way, the U joints can wear rapidly. An
axial load on a u joint will also generally accelerate wear and hence a
failure.
Yet another way is having two u-joints in a single shaft, and
the u-joints are "out of phase". This is because a u-joint speeds up and
slows down as it rotates (i.e. the output speed is not constant). So if
you have two U joints in series and one is speeding up while the other
is slowing down, there are very large loads imposed - and those loads
grow as drive shaft swings through a larger angle.
To summarize - U joints are happiest when properly greased, all
the needle bearings are where they should be, and the imposed loads are
torsional, coaxial and in phase.
The axles on the TR6 are keyed to prevent misphasing of the U
joints - but I don't know about the drive line. Is it possible to
misphase them? Someone else will need to speak up.
Vance
-----Original Message-----
From: owner-6pack@Autox.Team.Net [mailto:owner-6pack@Autox.Team.Net] On
Behalf Of Stuart Thompson
Sent: October 26, 2007 6:53 AM
To: 6 Pack list
Subject: [6pack] U-Joint Headaches
Listers:
<snip>
Busted another u-joint. This is the 2nd one in 3 years with little more
than 3000 miles on it.
Any ideas?
Stuart Thompson
|