2008 1200GS front wheel bearing replacement

NicD

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Having faffed about trying to understand the process, here is what I learnt

In addition to standard procedures

1. 100 degrees C bearings slide out. BMW spec 100 degrees. Cheap laser thermometer off Amazon makes it easy
2. Blind puller works better than drift as spacer is tight to bearing. 25mm collet fits
3. Replacement bearings are 6205 C3s with two rubber seals. NSK is like for like (6205 DDU C3)
4. Seat left hand bearing first. Heat to 100 degrees again. Slides in easily
5. Reason to seat left first is that this is the side the axle pulls on when you torque it up (according to BMW technician)
6. I used a Teng 36mm impact socket I have. Has 51mm od
7. Fit spacer
8. Fit right hand bearing. Check spacer is aligned while seating
9. Do not keep driving this bearing home. You need to seat the inner race against the spacer, and the aim is to have the two inner races and spacer move as one. It is correctly seated if inner race moves freely, and while moving freely the spacer and inner race of other bearing move with it
10. If the two bearing inner races move independently of each other, right hand bearing not seated enough. If inner races are reluctant to turn or stiff then right hand bearing has been driven home too far
11. If, like me, you drive right hand bearing in too far, use blind puller to move it back out slightly until you get the correct position
12. Pack seals with waterproof grease and seat seals
13. Fit left hand spacer with grease to seal left hand bearing inner race from water ingress

I'm sure others will add anything I forgot. In case of interest, you can tell if you screwed it up and drove bearings too far - on hard cornering I could feel a rumble through the pegs that has never been there before. Once I re-seated bearings correctly it disappeared
 
It also helps leaving the bearings in the freezer over night.

Don't forget it takes time for grease to unfreeze and work as it should do.

Thanks for an informative article.

Sent from my SM-G925F using Tapatalk
 
Personally I'm not a fan of bearings in freezer as they seem to attract condensation, and I think the temperature change is small relative to heating especially once you place them on hot hub (+80 degrees C versus -10; the change in temp, that is). But I don't think it hurts, and if tight clearance it may certainly help.

Saw this re the spacer length issue question i raised previously. Looks like a somewhat standard design feature. Had not noticed before. Not sure I agree with side loading implied by guy in the video, although he prob knows more than me

https://www.youtube.com/watch?v=_NqFwawlXw0
 
I put the bearings in a plastic bag and found an hour in the freezer was ample. They were down to -20 adding 30 to 40 degrees to the temperature difference. The bearing just dropped in so for the right side it was best to have the wheel lying flat. I used the spindle to align the spacer tube before dropping the bearing in.
 


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