Drive shaft oil supply drain plug question....

[Thickasabrick]

I have an R65 with build date of May 1985.  Have gone through a few things with this bike, and have drained and changed the oil in transmission, final drive and drive shaft.  The drain plug on the drive shaft (actually located on the forward housing of the final drive), didn't look like the rest of the drain plugs on the bike....as if replaced out of someone's bolt bucket.  The item had a broad built-in washer and there was some kind of hard rubber "gasket".  I believe the size of the plug to be 14x1.5 mm and the type of plug (magnetic) that takes an aluminum crush washer.  Can anyone confirm the size of the plug that I need?  The drawings on the parts places don't really show the drain plug for the drive shaft....it appears to show the drain for the final drive.....or are they the same size?  Thanks in advance for a confirmation.

[Bob_Roller]

A build date of 05/85 seems to fall into 'no man's land' .

Can't find it for a twin shock or mono-shock bike .

Which is your bike, a twin shock, or mono-shock ?

Here's a link to RealOEM for a build date of 04/85, a twin shock bike .

http://www.realoem.com/bmw/showparts.do?model=0364&mospid=51897&btnr=33_0619&hg=33&fg=10

What region do you reside in, Europe, North America, OZ ?

[Rob Valdez 79 R65]

I believe the size of the plug to be 14x1.5 mm

What makes you "believe"?  Did you measure it with a caliper?

RealOEM shows it to be a 12x1.5mm - and it is quite a bit smaller than the plugs on the final drive.

I suspect that someone stripped the threads once-upon-a-time (I've done it) and rather than a repair with a helicoil, they just went over-size with it.  Too bad - that can't really be fixed back to stock, not very easily, anyway.

Does it leak?  If not, I would just carry on.

These bikes are mostly* aluminum alloy castings with tapped threads receiving steel fasteners.  It takes a light touch not to strip the threads.  Especially on drain plugs when you are trying to stop a slow leak.  (That's how I did it.)


*Fork lowers, engine, gearbox and final drive.

[Thickasabrick]

The top is 12x1.5.....and what you said about a previous owner stripping it out then retapping, makes sense.  I would have thought both would have been the same size (top and bottom).  Incidentally, the top threads are pretty bad too.  I always change out the crush washer with a new one, and am careful when tightening.  This whole thing was discovered the first time I've loosened these plugs.  

Sorry about the build date....typo.....should be 05/1986 (My apologies)

It is a monoshock.....titled as a 1986.  I didn't measure with a caliper, just gooped it up and snugged it back on.....however the bottom was larger than the top plug.  

[Thickasabrick]

Thanks for replies....I'm going to have to remove that final drive and take a closer look.