Double row rear hub bearing

[Knowledge]

I have got one of the new style double row FAG bearings from AF Rayspeed and the bearing has two integral seals.

I would assume that I should remove the seal on the gearbox side, so the oil can get to it? Is this a correct assumption?

(AFR are shut until Tuesday, of course)

[rossclark]

I'd have thought if it's sealed it should be lubricated already and would be inclined to leave it.

[Knowledge]

Yeah, I was kind of thinking the same Ross, but then I have used shielded bearings on the drive side of the crank and always removed one of the seals. I guess the crank is running about 5 times faster than the layshaft.

There are instructions on the AFR website, but nothing about the seals.

http://www.afrayspeed.co.uk/index.php?page=catalogue_details&catID=891&listing=catalogue&attributeID=

[rossclark]

It mentions -

" The double labyrinth seal design provides a good seal as well as lower friction than the original garter seal. "

and

". The second proviso is you must ensure your crankcase breather is not blocked. The pressure holding ability of a Labyrinth seal is not as high as the original Garter seal. A blocked breather can pressurise the crankcase as it gets hot. Oil will be forced through the rear hub bearing and contaminate the rear brake shoes. The good news is that once the breather is corrected (and brake shoes replaced and drum cleaned) the seals will do their job once more. It is not necessary to replace the bearing if this happens."

Both of which would suggest to me that the seals should be left in place.

I like the look of this conversion better than the Jockeys one which requires shims ether side of the bearing and, although the bearing should be readily and more cheaply available, it looks no easier to change. It's a wonder no one has come up with a solution that allows it to be more easily replaced without dismantling the whole gearbox.

[Knowledge]

Hi Ross. I agree with your sentiments about the changing this bearing without dismantling the gearbox, but the new bearing feels super-stable, and perhaps it should not need replacing. It certainly rotates much easier than the traditional bearing and garter seal set-up.

For those who have not seen one of these bearings close-up, there is a groove in the outside bearing race with a sort of circlip in it. This takes the place of the shoulder on the outside of the traditional bearing. The whole bearing is thicker and the offset caused by the "circlip" means that despite the extra thickness, the bearing face will sit further from the end plate. This seems like the gearbox will need a thicker shim, even with a Clo5e 'box.

I need to take more measurements and get back to you guys, though some of my findings might find their way into forthcoming Oily Rag in Jetset.