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U-Joint Replacement - Part 2 of 2

Now that the old driveshaft is disassembled and cleaned up, it's
time to reassemble it with the new u-joints.

Remove the caps from the new joint piece carefully and watch out
for the needle bearings.  The bearing are normally packed into the
caps with some pretty thick grease and will usually stay in place
with no problems but watch out anyway.  Mark the caps so that you
can put them back onto the same part of the joint that they came
off of.  The new u-joints are symmetrical and it doesn't matter how
you reinstall them.  If the new joint has a grease fitting, you
should orient the joint so that the fitting is in the same
location as the old joint.  Make sure of this as you will not be
able to take the joint apart to "try again" if it is not correct
without damaging the joint.

Take one of the yoke pieces and put the new joint piece into it
so that the arms of the joint are inside the holes in the yoke.
We now need to install the caps into the yoke.  To do this, take
one of the caps (it doesn't matter which one) making sure you are
putting it back onto the arm of the joint that it came off of and
place it on the outside of the yoke facing inwards (with the open
part of the cap facing the joint in the middle of the yoke). 
Slide the joint as far as possible into the cap.  Putting the arm
of the joint into the cap when installing the caps prevents the
needle bearings from falling out and getting damaged.

Now take the yoke assembly and put it in a vise with one jaw of
the vise against the cap and the other jaw against the opposite
side of the yoke (which is still empty).  Slowly tighten the vise
to press the cap into the yoke.  Try to keep the joint piece
seated inside the cap while you do this.  Again, this is to
prevent the needle bearings from sliding out or getting misaligned.
Make sure the yoke is parallel to the vise jaw or the cap will be
cocked at an angle to the hole in the yoke and will be difficult
to start.

If you don't have a vise, I have pressed the caps into the yokes
by using a LARGE pair of channel lock pliers.  This is more
difficult to do but it can be done in a pinch.  If you don't have
a LARGE pair of channel locks and will need to buy them, I would
recommend buying a vise instead.  They are about the same price
(~$40).  BTW, these LARGE pliers are one of the most handy tools
in my toolbox and I would recommend that everyone have a pair. 
The jaws open to somewhere around 6" and the handles are over 12"
long (I think mine are ChannelLock #460).

When you have pressed the cap in to the point where it is flush
with the yoke, back off of the vise.  At this point, find a socket
or something else approximately the same size as the cap and put it
between the cap and the vice.  Make sure the socket you choose is
slightly smaller than the cap so that it can go into the hole in
the yoke without binding.  Align the socket on the cap and put the
whole assembly back into the vice and continue to press the cap
into the hole in the yoke until you feel it "bottom out".  When
the cap is all the way in, you should be able to see the groove
that the retaining clip goes into on the inside of the yoke hole. 
It is usually pretty obvious when the cap is all the way in
because the vice will become much harder to turn at that point. 
Don't tighten it down as hard as you can.  That's not necessary
and might damage the cap.

Flip the yoke over and do the same thing on the opposite side,
being careful to slide the joint piece over as far as possible
into the cap you are pressing in at all times.  When the second
cap is in place, there should not be any side to side play in the
center joint piece and it should not be binding.  It should be
easy to move and smooth.

Now just slide the other yoke piece over the joint cross piece and
repeat the cap installation procedure in that yoke.  Make sure you
have aligned the two driveshaft pieces the same way they were when
you took them apart (you marked them didn't you?).

When both yokes are done, reinstall the cap retaining clips.  If
the new joint has a grease fitting, install the old fitting in the
joint and add grease slowly until you just start to see grease
squeezing out from around the rubber seals on the inside of the
caps.

That's all folks!  Reinstall the driveshaft in the car and happy
motoring!  I hope I didn't scare anybody off.  It's not really as
hard as it might sound from the description above, I was just
trying to cover all the bases I could think of.  Remember to put
the center bearing back in the same location that it came out of
when you reinstall the driveshaft.  They normally have a small
pre-load on them.  If you have not replaced the "guibo" for a long
time, you might want to do that at the same time as the u-joints
and if the center bearing has any play in it or makes noise when
you spin it, replace that also.

I have never had to rebalance a driveshaft after replacing a 
u-joint.


Don Mies
85 635CSi (The latest of 8 BMWs) - Wonderful car!!
Thinking (very hard) about a Z3