Final drive Bearing, again!

[Rick 1600]

Hi guys.

F/D bearing packed in 10k ago when the bike had done 20,000 miles, (1150).
So changed the bearing and seal as instructions found on this here site.

I checked the oil in the F/D every month for scap metal.

6000 miles pass, all is well.

July comes, check it one more time then off for a 4000 mile run around Italy.

Return home, clean the bike up, quick check of the final drive oil and....yeah.... feck...metal in my oil!!!!

Just took it to bits, cage all twisted. Why is this happening? Prolonged high speeds? Heavy loads? Do I have to put another one in every service now???

Anyone know how to cure this so I can have a trouble free holiday next time?

Ta, Rick

 

[D6]

poorly shimmed up??

 

[Rick 1600]

Is the main bearing isnt shimmed ???

 

[Steptoe]

Is the main bearing isnt shimmed ???

It is.

 

[Rick 1600]

Ok, will do a search....

 

[Rick 1600]

Having trouble finding anything about shimming it though. Anyone got anything?

 

[Bronco Billy]

One of Steptoes pictures of a shim if you scroll down this thread link..

http://www.ukgser.com/forums/showthread.php?t=29409&highlight=bevel+bearing+shim

 

[Pekkavee]

Have a look in here
http://www.bmwlt.com/uploads/lt_final_drive_rebuild.wmv

From 35 min.

Pekka

 

[Rick 1600]

Thanks Pekka.

Ok, it is shimmed. How do if I know if its the right shim though? How do i shim it if it isnt?

 

[Popeye]

The shim is originally put in at the factory and is there to take into account the manufacturing tolerances of the bearing housing.

The manufacturing tolerances applied to the thickness of the outer race of the bearing itself will be very fine so once a shim has been matched and fitted to the bike it should be ok for the life of the bike and any number of bearing changes.

Did you warm the final drive casing so that it just dropped over the new bearing or did you need to tap or drive it home. If this isn't fitted squarly you will almost certainly suffer premature bearing failure.

 

[Bronco Billy]

The shim is originally put in at the factory and is there to take into account the manufacturing tolerances of the bearing housing.

The manufacturing tolerances applied to the thickness of the outer race of the bearing itself will be very fine so once a shim has been matched and fitted to the bike it should be ok for the life of the bike and any number of bearing changes.

Sorry but dont agree. If I changed out my bearing at home then I would get it shimmed up for the new bearing. You may be lucky, eight out of ten dont need the shims altering but you may have one of the two that do. The taper roller bearing that sits opposite the big bearing will deal with vast amounts of pre load cos thats what its designed to do. The bearing that we`re talking about is another kettle of fish and doesnt like side ways play. Another thing to note is if a bearing like this has failed prematurely then there is a reason for it, that could be poorly shimmed in the first place or quite commonly a jet washer being used and all sorts of crap being blown in from the back of the cover plate. These shims and pre load are needed to allow for the expansion of the materials used. You dont want any more side ways or lateral play than exists in the bearing naturally. Its ok to bang another bearing in to get you home if your on your travels but once home do a proper job and get it shimmed up spot on....

 

[Steptoe]

. Another thing to note is if a bearing like this has failed prematurely then there is a reason for it,

Yes - and we don't know how it was replaced the last time - was the final drive cover heated so the bearing and crown wheel just dropped in place, or was the crown wheel placed in the housing and the cover just tightened on to it by the bolts ?

 

[zerocool]

Sorry to jump in mid thread with a question but how much play would you expect in the rear wheel if the bearing needs replacing? The stealers just shake it about and say "yeah it needs doing" from the feel but I was wondering what that "measurement" should be.

Mine was done 20k miles ago and im guessing im about ready for it.

 

[Steptoe]

Sorry to jump in mid thread with a question but how much play would you expect in the rear wheel if the bearing needs replacing? .

None at all in the final drive bearing - Are you confusing the final drive bearing with paralever bearings ?

 

[Bronco Billy]

Sorry to jump in mid thread with a question but how much play would you expect in the rear wheel if the bearing needs replacing? The stealers just shake it about and say "yeah it needs doing" from the feel but I was wondering what that "measurement" should be.

Mine was done 20k miles ago and im guessing im about ready for it.

"Play" should not be present. If the play goes away when the back brake is applied then its the bearing. Otherwise its the trunions .... Thats what Steptoe taught me any way ..... .......