Another bearing question...

[isham-research.freeserve.co.uk at pop.pol.net.uk]

> I'm back from the shop who did the bearings. This is how it's going to
> go. The bearing was pushed in with a vice, but eventually we had to go
> to a place with a small hydraulic press. The bearing popped back and is
> now flush with the rear of the housing. I bitched alot about what you
> guys said about the proper install procedure, but got nowhere. I said
> when the struts go on the car and I have a stuffed up bearings I'm
> coming back to get new ones. The answer to this was that that'd be fine,
> but that I would not have the problem.

A VICE!!!??

Insertion force is round about 12 metric tonnes with a dry bearing and
hub.  You _NEED_ a hydraulic press - and not a small one, either.  I
suspect the outside of the bearing was greased - if so you MUST reject
the hub and not use it on your car.  The microfiche is quite explicit:

  "Hinweis:

   Das neue Radlagergehaeuse darf vor dem Einpressen
   des Radlagers in Bereich des Lagersitzes _nicht_ _gefettet_
   werden."

   Fahrwerk Allradantrieb Ausgabe 07.87 D000.5147.30.00 40.13

   [The words "nicht gefettet" are underlined on the microfiche.]

  "Note

   The new wheel bearing housing _may_ _not_ _be_ _greased_
   in the area of its seat before the wheel bearing is pressed in."

> I asked about the install procedure. It seems to clash with what I've
> been told is the correct procedure. First the bearing is pushed in half
> way, then the hub is installed on the inner race and the hub and bearing
> are forced in together. Much mechanic speak was given out about them
> having done it this way forever on press and vice with no side effects.

It's possible they managed to reduce the true insertion force by
greasing, but as the above indicates this is not allowed.  The
corollary, of course, is that less lateral force will be taken by the
interference fit and more by the circlip.  The fact that Audi deleted
the circlip in later cars should tell you how much force Audi intended
it to take.

That bearing is designed to carry 1/4 of the weight of the car applied
in a direction at right angles to its axis, and 1/4 (very roughly) of
the mass of the car multiplies by your maximum cornering G force.  It is
not designed to take 12 metric tonnes axially.

Their install procedure, of course, is about as wrong as it could be.

> I did notice that this bearing is a double ball-bearing unit. This
> installer told me you can't damage the bearing pushing it in like he did
> because of the step between the 2 rows of ball bearings.

Ask SKF's technical support line what _they_ think.

Your installer should stick to lawnmowers.

--
 Phil Payne
 UK Audi quattro Owners Club
 http://www.isham-research.freeserve.co.uk/quattro
 Phone +44 7785 302803   Fax: +44 7785 309674