While we're on the subject of hubs and bearings...

[fabiano]

After warping 3 sets of rotors my local shop tells me they found the problem. My front hubs are warped! That's why I keep warping the rotors. He say's Porsche issued a service bulletin back in '94 on this so I must not be the only one with this problem. Has anyone else experienced this? I found a set of used hubs for $100 each. New ones are $600 each. I don't want to get used ones if they may warp also. Help! If I spend much more $$ on this car I'll be sleeping in the back yard!

Thanks!
Steveo
'90 944 S2 Cabrio Black/Black

[AFJuvat]

I've heard of it - it was one of those "replace as needed" parts. Some had the problem, others didn't.

The original part for your model year was replaced.

The new part number is:

944 331 067 01

if the used ones have that part number, you should be good to go.

AFJuvat

[SoCal Driver]

Why can't the wheel studs be removed, the hub normalized (heat treated) and the mounting face resurfaced/turned?

[fabiano]

Thanks AFJuvat! Could you check that part number? They tell me 944 331 067 01 is a part number for rear hubs and I need fronts. The hubs they have are 951-341-065-06 but they may have others also.

[Britwrench]

I am reasonably sure that the bulletin only refered to 993 models.
However it would be applicable to any car, not only Porsches.
The usual problem is the wheel nuts being tightened with an air wrench. Porsche forbid this (and so no-one uses them..) You can rotate the disc on the hub until a more favorable run-out is measured. If that doesn't work it's new hub time.
I can't really see any reason not to machine the hub face, but you would have to ensure that the caliper was centralised.


Porsche, like Mercedes and BMW now use wheel bolts, part of the reasoning was to prevent the hub "pulling" when the studs are pressed in.