Final drive leaking

[AlfromNH]

not to start another "me too" thread about oil leaks...

I discovered oil all over my rear tire/rim after my first rides on this bike. The final drive drain plug was dripping with oil, so I thought it was an easy fix and replaced the sealing washer on the drain plug.

It sill leaks. Upon closer inspection, I discovered this weep hole, which I strongly suspect is the source of the oil. I stuck a piece of wire up there and it comes out oily.


The inside of the brake drum is dry, thankfully. And the bike didn't leak for a couple weeks of sitting full of oil before I got to ride it. So apparently oil getting thrown around inside the FD let it find spots to escape.

What is the purpose of this weep hole, if that's what it is? And am I looking at disassembling the final drive?

[donbmw]

The seal for the final drive gear is leaking that is what the weep hole is for. Let's oil drain out and not get on your brakes.

Don

[montmil]

A bike laid up for a long winter's nap may have some very stiff seals when initially awakened. A few rides may help the seal become a bit more flexible as it warms and goes back to work.

Have you switched the final drive to synthetic oil? The leak might stop with a return to dino. Replacing the seal is not a difficult chore and requires no special tooling. I've done one of the R65s plus a recent job on the R100S. Should you decide to replace the seal, remember to order a new Cardan cover gasket, too.

[AlfromNH]

Thanks for the info, guys. I'm running Dino oil. I bought this fd used and don't know its history.

I'll be in the vicinity of Max NH today, if they have the parts in stock I'll pick them up. Replacing a gasket and seal doesn't get me into the realm of shimming, I take it?

Monte, the cardan cover is what is held on buy the circular bolt pattern? Where does the name cardan come from?

[montmil]

You will not need to re-shim the crown and pinion gears if you simply replace the seal and gasket. Just don't lose them during the disassembly.

After removing the bolts, those two open and threaded holes  you're wondering about are used to insert smaller bolts and, by tightening them equally, will aid in lifting off the Cardan cover.

You will need a propane torch as one of your tools. That and a trimmed beer can -preferably emptied in the proper manner. I have some photos to post later. Need coffee now.

Last thought... Sometimes the final drive is over-filled. I do not use that "fill 'til it dribbles" bolt nor do I use the full spec amount of gear lube. Just a little less can stop those annoying dribbles. Pampers just don't look right.

Cardan Joint
A type of Universal joint named after the Italian Cardan who developed the concept in the 16th century. In the 17th century, Robert Hooke of England developed and patented the conventional universal joint. Sometimes it is called the Cardan universal or the Hooke universal. It has two Yokes at right angles to each other.

You need something to cover your Cardan Joint. Let's keep it simple and call it a Cardan Cover. [smiley=thumbsup.gif]

[AlfromNH]

Went to Max this afternoon and picked up the gasket and 2 different seals. Got home and disassembled the final drive.

It came apart very easily, to this point:



Now, according to the Clymer manual, that big ball bearing should have stayed on the ring gear, to be tapped off using the holes in the ring gear.

So how do I get the bearing out of the "Cardan Cover"? Is that what the propane torch is for?

And Monte, thanks for the definition of "cardan". But why is this cardan cover covering a ring and pinion?  

[montmil]

Yes, if the bearing didn't come off with the ring gear, you can warm up the alloy and the bearing will come off easily.

I've slept since I did the last seal on the R100S, but can't you access the seal from the other side and leave the bearing in situ? Be sure to note how far into the aluminum casting the seal is sitting. Sometimes. it may be necessary to adjust the position a wee bit to get away from any excessive wear pattern that may or may not be evident.

As to how the Cardan cover got its name and why BMW refers to it, I dunno. Try not to lose too mauch sleep trying to figure it out. Focus on the job at hand, Al, Focus.