This info might be usefull to anyone with worn driveline components and or vibrations.
There are two shafts joined in the centre by an unconventionally fitted universal joint.
At the tranny end there is a Guibo (Italian for big black rubber joiner gizmo) and at the diff end an almost conventional C.V. joint the allows for a small amount of back and forth movement.
There is a bearing in a cage that bolts to the floor at the centre join which is unique to BMW. Its a German brand bearing that is sealed front anfd rear but its wder than the common bearing with a similar part number so allow enough time oof road to procur one through a bearing company if you dont want to contribute to the BMW benevolent society fund.
CAUTION WHEN SPLITTING THE SHAFTS for replacing the bearing or cage. The yokes are not marked to identify the correct re assembly point and there is onl one position that will give you the same balance as you had prior. Rember to mark them accordingly as there are about 28 splines and only one is correct fit which means you could spend forever trying the other 27 positions to get rid of the vibration you have just casued!
The Rubber Guibo gizmo is a common cause of vibration in the driveline. seems they are good for about 80,000 to 100,000 klms and then they crack and or go out of round.
Similarlty the rear tranny mounts (two of) disintegrate and will cause vibes and or a clunk in reverse as the rotation/torque changes direction. Replace them while you have it apart. they are cheap and can be found non BMW.
The replacement of any component is time consuming but easy
1. raise the car onto safety stands or a hoist.
2. drop the entire exhaust from the front joins
3. renove the heat shield
4. remove the tranny rear support bracket after supporting the tranny
itself from dropping. two 13 mm bots at the top of the mounts need to
be opened a turn then it just slips backwards and out
5. undo the three bolts that hold the Guibo gizmo to the tranny flange
leaving it attached to the shaft
6. undo the six nuts on the CV about two turn and tap the bolts with the
crimp nut still attached. They have a tight fit spline in the CV and to
enable the assemby to come out you need to work the bots right out
7. drop the bearing cage AFTER MARKING THE POSITION WITH SOME
PAINT. That way you know it will go back to where it wasnt a problem.
8. it's almost ready to drop by itself but you may need to gently pull at
the joint
Reassembly is the reverse but look closely at the Guibo Gizmo before
removing. It has arrows to front and rear so be aware of which arrows
mate with which flange. Same goes for the C.V if you pull it apart. Best
to just force some new grease in without dissassembly.
Finally the universal joint. It's a bastard design only because the cups
are not held in with circlips or like anything you will have seen before.
Look closely you will see that the yokes are sort of crimped to stop the
ups from coming out. If removed there is no way for most workshops to
reinstall (at least on a permanent basis) and certainly you can't centre
the Uni which guarantees it to be 'out of balance'.
There are specialist balancing engineers around that have
made jigs and special tools but be confident in their abilty and that they
regularly do BMW or Mercedes shatfs 'coz they are very diffent from
anything else you have seen before.
In summary, it sounds complicated but it's not. Any home mechanic or
enthusiast with a few tools any safety stands can do this job. Take your
time and think about each step as you go and you will save yourself a
lot of hard earned that would be better spent on a nice set of wheels or
whatever flicks your switch!
Theo from Australia
