1150 Final Drive

[slaphead GSER]

I have a 2002 1150GS which has had its third Final Drive bearing fitted, first one went at 19,000 , second one at 26,000 and most recent one at 36,000 .
There is now 38,000 and after pulling it apart there seems to be roughness in the latest one ( fitted in a garage in Croatia on hols ). To my mind people have replaced this bearing without checking the shims , I removed two shims 0.50 and 0.30 mm and rebuilt the unit allowing the cover to pull the shaft in to its correct position , removed the unit and measured the gap where the shims normally are and found the gap to be 0.60mm. The question is if I replace the original shims (0.80mm ) with a 0.60 shim could this differance of 0.20mm have put enough preload to make the final drive bearing fail so often ?

 

[FatAl]

Hopefully someone like Steptoe will advise you on this. My feelings are that the shimming is very important. A few years back I helped a mate replace his rear drive bearing, we just put the original shim in, just chanced it I suppose, however the bearing had to be replaced 12 months and about 8000 miles later.
He again replaced the bearing, again put the original shim in, and then sold the bike on through the trade. Last year he met the new owner by chance who reported that the rear bearing failed (about 7000 miles after the last one).
Personly I'd try to shim it as accurately as possible.

 

[Steptoe]

and rebuilt the unit allowing the cover to pull the shaft in to its correct position , removed the unit and measured the gap where the shims normally are and found the gap to be 0.60mm.?

Fitting it in that way would have sideloaded the bearing. So any measurements are meaningless.

 

[MattW]

If you've got the patience of a saint, you can sit through this (very strangely edited) video which shows a technique for measuring the clearance and calculating the required shim thickness.

http://www.bmwlt.com/uploads/lt_final_drive_rebuild.wmv

As Steptoe says, loading the bearing by pulling it all together using the casing will put your measurements way out - you need to get it assembled without loading the bearing (heat / freezer or a mixture of both) before measuring the clearance and calculating the shim thickness etc (not forgetting pre-load). The video shows a method for doing this without special tools. Whether the method in the video is any good or whether it's worth doing it yourself or just sending it away is your call

 

[slaphead GSER]

I maybe din't explain it very well in the first thread , I haven't taken the bearing of the shaft yet so when I said I was drawing the shaft in using the 8 bolts that retain the cover , surely this little amount of pressure would equate to the same force to tighten a normal taper roller bearing therefore the gap that is left after tightening would be equal to the shim that I need !

 

[Steptoe]

I maybe din't explain it very well in the first thread ,!

You haven't explained it any better in the second post.

 

[MattW]

You haven't explained it any better in the second post.

I was waiting for someone else - I thought it was just me...

 

[slaphead GSER]

OK OK OK , will try again . Shaft complete with taper roller bearing crown wheel and big bearing , tap the cover ( with shims removed ) onto the shaft untill the bearing is about halfway in then insert the assy into the casing ensuring crownwheel and pinion are aligned then use the eight 7mm allen key bolts to draw the shaft completely home. I know this is putting a load on the taper roller bearing but the alloy cover is not a tight fit so I am thinking this load would be next to nothing but it leaves a nice gap where the shims should be. Get the feeler guages out and measure the gap and this would give the size of shims needed. Without the proper BMW tools this is the nearest way of doing it that I can manage. If there is a more accurate way please please please explain .................................. !

 

[MattW]

OK OK OK , will try again . Shaft complete with taper roller bearing crown wheel and big bearing , tap the cover ( with shims removed ) onto the shaft untill the bearing is about halfway in then insert the assy into the casing ensuring crownwheel and pinion are aligned then use the eight 7mm allen key bolts to draw the shaft completely home. I know this is putting a load on the taper roller bearing but the alloy cover is not a tight fit so I am thinking this load would be next to nothing but it leaves a nice gap where the shims should be. Get the feeler guages out and measure the gap and this would give the size of shims needed. Without the proper BMW tools this is the nearest way of doing it that I can manage. If there is a more accurate way please please please explain .................................. !

It's not the load on the taper roller that's the problem - you're putting a side load on the big bearing when you draw it home with the cover (inner to outer race) - this will distort any measurement you manage to take.

 

[slaphead GSER]

OK , I know where you are coming from but surely the amount of side load I would be putting on the big bearing would be a couple of thou at the most , if I make a calculated guess and air on the smaller amount ! Hursts Mottarad in Belfast dont have the specialist tools required and have never requested them , they just replace the old bearing with a new one and leave the shims alone. This is a mates bike and every time the bearing has gone he has been on hols abroad ( well once in Scotland ) so I am just trying to persuade him to keep GSing but I think his patience is wearing thin. Dont want another FD failure !

 

[MattW]

OK , I know where you are coming from but surely the amount of side load I would be putting on the big bearing would be a couple of thou at the most , if I make a calculated guess and air on the smaller amount ! Hursts Mottarad in Belfast dont have the specialist tools required and have never requested them , they just replace the old bearing with a new one and leave the shims alone. This is a mates bike and every time the bearing has gone he has been on hols abroad ( well once in Scotland ) so I am just trying to persuade him to keep GSing but I think his patience is wearing thin. Dont want another FD failure !

It sounds like his FD was shimmed wrong from the outset and the dealer just changing the bearing isn't fixing the problem. That said, they aren't alone - most dealers don't want to get into properly shimming transmission bearings. They usually just seem to want to swap out the FD for a new one.

In your position, taking 'educated guesses' is just a lottery - you might end up lucky, you might not Watch the video - it shows a technique that doesn't require guesswork but whether you want to get into it is another thing. In your case, I'd seriously consider sending the FD away to someone like Steptoe or Scriminger and get them to properly shim it to factory specs.

 

[tomw166]

Whilst we are talking about shims, can I get them from my local dealer?

 

[Decster]

It sounds like his FD was shimmed wrong from the outset and the dealer just changing the bearing isn't fixing the problem. That said, they aren't alone - most dealers don't want to get into properly shimming transmission bearings. They usually just seem to want to swap out the FD for a new one.

In your position, taking 'educated guesses' is just a lottery - you might end up lucky, you might not Watch the video - it shows a technique that doesn't require guesswork but whether you want to get into it is another thing. In your case, I'd seriously consider sending the FD away to someone like Steptoe or Scriminger and get them to properly shim it to factory specs.

sound advice and at least peace of mind after the deed is done

 

[davegs]

OK , I know where you are coming from but surely the amount of side load I would be putting on the big bearing would be a couple of thou at the most , if I make a calculated guess and air on the smaller amount ! Hursts Mottarad in Belfast dont have the specialist tools required and have never requested them , they just replace the old bearing with a new one and leave the shims alone. This is a mates bike and every time the bearing has gone he has been on hols abroad ( well once in Scotland ) so I am just trying to persuade him to keep GSing but I think his patience is wearing thin. Dont want another FD failure !

Do as the man says, either send it to mr S of this establishment for a good job or get another bevel box from motor works they are not the things for guessing games.
Dave GS

 

[slaphead GSER]

To TOMW166 , my local BM dealer has to order them from Germany as there is about 18 of them rangeing from 0.1 mm to 1.7 mm ( aprox ) and in all their years they have only ordered them once to replace damaged ones !
Hope this helps .....