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31310
05-17-2009, 05:43 PM
Looking in the service recommendations, haven't seen reference to repacking the wheel bearings. Do it annually on my '83RT and wonder when or if it is required on the hexheads. Presume my question is for the front wheel only btw.

henzilla
05-18-2009, 03:34 PM
They use sealed bearings now. Have only seen one set damaged on a 07 K12GT due to over torqueing the axle . Bro in law put a new set on his 07 R12R Roadster at 100K just for grins. They were not showing signs of wear, just peace of mind

31310
05-19-2009, 03:47 AM
Thanks for the reply; hope the sealed for life works better than the lifetime fill at the other end of the bike.

deilenberger
05-19-2009, 01:33 PM
Thanks for the reply; hope the sealed for life works better than the lifetime fill at the other end of the bike.BMW has been using sealed bearings since about 1983 on the K bikes.. and so far it seems to have worked out fairly well. Lots of people have gone well over 100-200k miles on the original bearings. Of course there may be exceptions - and overtightening the axle on some models can increase the loading on the bearings - but it does that also with airheads so.. (a friend goes through the bearings on his airhead every 6k miles - and doesn't know what he's doing wrong. I suspect overtightening the axle..)

31310
05-19-2009, 04:18 PM
I was completely unaware BMW switched to sealed bearings so long ago. Guess when you only concentrate on one series of bike, one falls behind what else is happening in the world. Until being taught how to preload wheel bearings on my '83, I too trashed them annually. Thanks for the info Don.

deilenberger
05-19-2009, 07:08 PM
I was completely unaware BMW switched to sealed bearings so long ago. Guess when you only concentrate on one series of bike, one falls behind what else is happening in the world. Until being taught how to preload wheel bearings on my '83, I too trashed them annually. Thanks for the info Don.
No problem. The need for accurately preloading the bearings changed with the design BMW used on the K bikes.

In this design, one bearing is a simple ball-bearing, the other bearing is a ball-bearing with a wide race - meaning the center portion of the bearing could move in/out in relation to the axle.

What that means is when the axle was clinched up against the bearing - that bearing center will move and make full contact with the spacer between the bearings, which then makes full contact with the center of the other bearing.

What this results in is a bearing assembly that can withstand over-tightening without exerting too much preload on the bearings. Clever design.. it results in much longer bearing life. I suspect the newer boxer bikes also received it.

Best,