CV axle bearing question - passenger front

[dswilly]

New guy here with a 04 3.0 6spd. As with any older car, there are a few things to do once you are in possession. Tracking down a oil leak, it ended up (mostly) being from the passenger side front axle seal. Removing the CV was easy but the axle bearing in the support carrier came out with the axle. Not a big deal as I am replacing both cv axles and ordered a new support carrier with the bearing, o-ring and seal included. Why would the bearing stick or seize to the axle? The axle was a GSP and I ordered the same as replacements. Would it be the axle tolerance to the bearing or just old stuff sticking? Any help is appreciated.

[andrewwynn]

not sure what bearing you are describing; in the oil pan ? that won't usually hold on to the axle but I think it is just press fit into the oil pan, so if it got just a little rust on the inside of the axle shaft could easily pull that out if I'm remembering correctly there's no snap ring. You mentioned leaking seal so maybe not enough oil to keep that shaft wet so rust could form?

[dswilly]

Yes, it's the passenger side that sits in the support carrier that attaches to the oil pan, the long side. As best I can tell, the bearing should be exposed to diff oil when all is well, but in my case, maybe it got starved a bit and rusted, etc. It is press-fit into the carrier.

[andrewwynn]

yeah I forgot there's an actual separate part that attaches to the side of the oil pan. swapped two motors last year you'd think I'd have remembered ... I didn't change the bearing so I wasn't sure but I have changed more than a few CV axles and never have they pulled the bearing with so you have a one-off there.

[dswilly]

Yeah, I don't think this is a common fail point, thus the lack of information on it. I didn't even see a replacement bearing option outside the entire carrier.

[wpoll]

Originally Posted by andrewwynn

... I didn't change the bearing ...

For some reason, BMW say the bearing cannot be changed - and the carrier ships with the bearing installed.

14 Supporting bracket 1 31537503119

GROOVED BALL BEARING
may not be replaced

Possibly because installing the bearing risks splitting the alloy carrier?

[dswilly]

Originally Posted by wpoll

For some reason, BMW say the bearing cannot be changed - and the carrier ships with the bearing installed.

14 Supporting bracket 1 31537503119

GROOVED BALL BEARING
may not be replaced

Possibly because installing the bearing risks spitting the alloy carrier?

That makes sense. Fortunately the support carrier includes the seal and o-ring is not too bad @ $175

[80stech]

Many times in such cases there has been a change or update to improve something so they make you buy the whole unit. A good example was the oil filter adapter plate O-ring for the E30 was not available separately and you had to buy the whole adapter plate with new O-ring but the reason was that the O-ring groove in the replacement was machined to provide a little more crush on the O-ring to keep it from leaking again. I think it was just a case of poor engineering specs or maybe O-ring material or spec not matching the groove. Gleaner combines had exactly the same problem with their hydraulic filter block. I wouldn't be surprised if the new bearing/housing was somehow different. Was the original bearing not a sealed unit ??

[dswilly]

The bearing is not sealed. I assume the cavity that the axle passes through the oil pan in is filled or at least exposed to the differential fluid, which would mean the bearing is as well up to the axle seal itself. I had leakage there and it was gear oil. They also have an o-ring where the carrier mounts to the oil pan which can leak.
I have to admit, when I do the volume math in my head and the differential spec says 700mil to fill, including the shaft cavity through the pan that doesn't sound like much.

[wpoll]

Originally Posted by dswilly

... I have to admit, when I do the volume math in my head and the differential spec says 700mil to fill, including the shaft cavity through the pan that doesn't sound like much.

I've always thought that too but I guess the diff itself doesn't have terribly much fluid capacity - it's full of pretty solid gears, pinions, shafts etc.