[V8] Replacing rear wheel bearings (propshaft support)

[Buchholz, Steven]

Methinks the decision Audi made is one of practicality, and frankly I don't
fault them too much for it.  We make similar decisions where I work ... to
what level do you want to define a "FRU" ... field replaceable unit?  Given
that the propshaft is a balanced item would you want the service techs doing
a full R&R on a propshaft u-joint or carrier assembly?  Would the labor
required to repair the unit cost the same as a full replacement?  If so,
there would be no reason to stock repair parts.  
 
As to propshaft repair-ability ... I have returned a propshaft with a bad
carrier bearing in my urq to service ... in fact I've never had to do
anything other than grease the u-joint in the many years since.  Perhaps the
biggest problem is that there appear to have been multiple "flavors" of
propshafts over the years, each one requiring a different solution as
regards the carrier assembly.  It is my understanding that in many cases
there is a BMW part that can be called in for repair ... but it is also my
understanding that it is rarely a "drop in" solution ... some sort of
modification is required to make the thing work.  I was lucky on the urq in
that it was possible to replace the carrier bearing independent of the mount
... but from what I hear the newer cars have the bearing bonded to the
mount.  
 
When you consider the fact that with a brand new propshaft you would be
getting brand new CV joints and a brand new u-joint with that carrier
assembly that you know will bolt right into the car, perhaps it isn't all
that bad a thing to pay the freight for a new propshaft ... but I'd only go
that way after a bunch of kicking and hollering myself ... ;-)
 
Steve B
San Jose, Kaleefohnia (USA)

Speaking of the propshaft support bearing, mine turns like a pepper
grinder...well not quite that bad.  I have the propshaft hanging bc the
trans is out.  I know Audi only sells the center support along with the
entire propshaft as a unit.  I do not know, however, how they could ever
justify this.  I guess I could try and see if McMaster Carr has the same
sized bearing but I would also like to also replace the housing/support.  It
looks like there is a 17mm bolt holding the two sides of the shaft
togeather.  It does not look like there is room for a spline.  Will the two
sides pull apart once I remove the bolt?  I have heard that a BMW unit can
be made to work...any BTDTs?  Thank in advance.