Drive housing issue

monster-mash · Feb 16, 2020

Slowly putting back together my G/S and noticed slight oil weep from diff, firstly no gasket between drive shaft and housing guessing there should be one but i cannot see it on realoem also and perhaps worse there is a M8 described as a screw plug halfway up the housing rearmost and the thread has been stripped. maybe helicoil it but really didn't want to strip this unit down. Can anyone advise, its part number 15

pleasehttps://www.realoem.com/bmw/images/diag_3ba.png

Mistacat · Feb 16, 2020

It sound like the level plug M8 X 1mm pitch, why on earth BMW used a fine pitch in aluminium is beyond me.
I have helicoiled loads of these and when they get butchered further I have to weld them up and re-tap them to the dreaded M8 X 1 mm pitch to use the original plug.
You will have to strip it if you helicoil it as the seat needs to be cut true to the thread .

monster-mash · Feb 16, 2020

Thought this would be the case, to do the job correctly Im going to have to strip the drive down so as i can ensure all the metal swarf is removed. Any special kit needed to strip this down or rebuild it do you know?

Mistacat · Feb 16, 2020

Best to have a word with Mikeyboy (Overland and Classic) He sends the bare casings to me to be done.

mikeyboy · Feb 16, 2020

monster-mash said:
Slowly putting back together my G/S and noticed slight oil weep from diff, firstly no gasket between drive shaft and housing guessing there should be one but i cannot see it on realoem also and perhaps worse there is a M8 described as a screw plug halfway up the housing rearmost and the thread has been stripped. maybe helicoil it but really didn't want to strip this unit down. Can anyone advise, its part number 15

pleasehttps://www.realoem.com/bmw/images/diag_3ba.png

Gasket or no gasket depends when it was made,
Earlier bikes had a gasket fitted ,later ones did not ,and a bit of decent sealant is the order of the day,
This also applies to the joint between the swingarm and final drive.
Bear in mind also,if you were to fit a gasket when one was not fitted originally it will mess up the shimming.
As Chris has said ,the unit needs stripping to repair the thread,
The unit is not overly difficult to work on,but the pinion assy has a castilated nut which needs a special socket to remove.
And there are a few tricks of the trade to get them apart

r100gser · Feb 16, 2020

As a stop gap you could try loctite 603 or loctite 545 or 569. Below is a link to show how they might be used

https://youtu.be/x8tx-cBulno

Also have a look at. https://youtu.be/k22JIBx9-CQ

Or. https://forums.bmwmoa.org/showthread.php?39065-Rear-Drive-Level-Plug-Stripped

Or. https://bmwmotorcycletech.info/rearwhlsplines.htm

Good luck...ian

monster-mash · Feb 17, 2020

Great information guys, as i am just wanting to get it on the road to see how the rest of the bike performs i think i will fix/glue in place for now keeping an eye on the fluid. I will give the gasket a miss as there wasn't one there beforehand & couldn't see one on the part breakdown and smear a dab of hylomar. Be in touch some time in the future Mikeyboy
Thanks again all

mikeyboy · Feb 17, 2020

Hylomar is a bit dated nowadays,and a bit Shiite,get some wurth rtv,in silver,far better.!
You don’t need to put loads on,literally just a thin coating,if it squeezes out everywhere there is too much

Beemerboff · Feb 18, 2020

BMW specify Loctite between the drive shaft and the final drive housing, the grade specified may be hard to find today.

You shouldn't really need to remove the pinion to cut a thread on the level plug.

I have helicoiled them by hand, but my homemade tap holder is 15 inches long and a bit easier to keep straight than a shorter one!
Never had any problems with the plug leaking - usual problem is that large output bearing is loose in the cover, but that does not seem to bother anyone who has posted " how to" videos on Utube or elsewhere!

mikeyboy · Feb 18, 2020

Agreed,the pinion does not necessarily need to come out,but it would be a good idea to replace the oil seal whilst it’s stripped down,and worthwhile taking a looksee at the bearings.

Beemerboff · Feb 18, 2020

Shure, but working on the pinion needs a few special tools, and when you have reset the pinion you will have to reset the wipe pattern, then you will need to re shim the output bearing so it ends up a complete rebuild, which requires the tools listed in Clymer, and you can't buy them any longer.
So, all or nothing.

Drive housing issue

monster-mash

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Mistacat

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monster-mash

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Mistacat

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mikeyboy

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r100gser

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monster-mash

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mikeyboy

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Beemerboff

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mikeyboy

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Beemerboff

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