Finaldrive strange oil leak

[michnus]

We were out riding on Sunday when the bottom bolt holding the rear mudguard to the final-drive, somehow got out and nearly
all the final-drive oil got pumped out that hole.
Phoned BMW-on-call and 1hour later the BMW dealer picked my bike up. This is the interesting part, the thread holding the bolt in
the final-drive was stripped and the bolt just vibrated out on the dirt road. How long it was like that no one would ever know.
Fact is a BMW mechanic or the previous owner took the mudguard
of and when they refit it they stripped the thread.

Other interesting bit, today someone in BMW head office mentioned the hole goes straight through into the
final-drive, I personally know a few people that took the
mudguard off and ride their bikes without the thing, why is there no oil pumped out of their final-drives?
Secondly dirt will surely go in the hole and mess the final-drive up? If that's the case then my final-drive broke a seal or
something to allow the oil to get out the hole.


Can anybody tell me if that hole is a blind hole or in fact do go through into the finaldrive casing?

 

[Dutchman]

It's a blind hole......

D

 

[whitegloss]

seems possible the right bolt had not been replaced and maybe screwed into the blind hole to far, causing it to puncture the casing of the final drive

 

[B Murr]

so there could be a bit of casing in there getting into the drive?

 

[Ken H.]

There doesn't seem to be a lot of consistency. I've seen more than a few that are blind holes, and quite a few that went all the way through.

 

[michnus]

Mine pumped the oil out, I could stick a thing in there and it will be covered with oil, if other peoples bikes holes are open then why do they not pump the oil out theirs?

 

[Timpo]

Holes blind.

seems possible the right bolt had not been replaced and maybe screwed into the blind hole to far, causing it to puncture the casing of the final drive

Whitegloss I'm with you.
My hole is defo blind and your theory sound spot-on.
So, there oil will have a piece of ally casing swimming in it....or maybe not.
It's either stuck at the bottom of the casing or it will of been chewed up to nothing by now.

You have a couple of options for repair, helicoil + loctite thread seal or a blob of ally weld and no fitting of the fender......or a brand new casing (£***)!
Best of luck.
Timpo.

 

[michnus]

BMw changed the oil for me, there was no trace metals in the remaining oil that got drained. They retap the hole and sealed it with a new bolt minus the fender.

It is just to confirm the hole is indeed blind in all the bikes.

 

[steve16]

Mine did that..

........when I removed the screw in order to fit the hugger.The hugger came with a plug to cover the hole.I noticed oil leaking out (slowly) so I took the bike into the dealer (after checking a few other 1200GS) and when the dealer checked some of their bikes the Final Drive was changed under warranty...

 

[Gipsy]

It's a blind hole......

D

Have just this very moment got rid of the crap catcher and had a good look down the 3rd hole. On my unit there is definately a very small hole at the bottom of the threaded part which extends the hole further. Didn't probe the extension as didn't have a wire fine enough to pass.
If as it's been suggested earlier in this thread there is an inconsistency as to whether this is a blind hole or not, some peeps who have not sealed it properly after removing the crap catcher may be storing up probs for the future.