R75/7 Oil leak around shifter

[slamiste]

Last year my very oil tight BMW R75/7 started leaking oil around the gear shift lever where it goes through the case. I replaced the output shaft oil seal but I still have an oil leak. Today when I removed the shift lever I noticed the bolt that attaches the shift lever was heavily coated with oil. I don't see any sealing mechanism between the shift lever bolt hole and the bolt so is it possible the oil is leaking out through the gap between the bolt and the hole it goes through? Also I don't see any noticeable groove on the shift lever where it contacts the seal. Any ideas on what I should investigate?


Steve Slaminko

[Rubone]

Make sure the transmission vent isn't plugged up. When running the pressure build-up in the case needs to go somewhere and if the breather is plugged the pressure will find the next weak spot to exit carrying oil with it.

[slamiste]

Thanks Robbie,

Today I looked for the vent on the transmission but was unable to locate anything that would serve as a vent. There was a small Phillips head screw under the air filter on the right rear of the trans top that didn't seem to have any function that could maybe serve as a vent however the screw has no provision for venting. So while I hesitate to keep asking you for help can you tell me where the vent is located on the R75/7?

Steve Slaminko

[jim d]

Look at the retaining bolt that holds the speedometer cable into the transmission.

[slamiste]

Thanks Jim,

That's where the vent is! Now it seems I've got a bigger problem due to my lack of knowledge on BMW's. The little screw I mentioned that I removed on the top right rear quadrant of the transmission under the air filter was apparently attached to something inside the transmission that is now out of position, perhaps totally loose in the trans. The only way I can see to remedy this is the remove the transmission and open it up to repair. If that's the case so be it but if you or anyone else has any alternate solutions I'd like to hear them.

Steve Slaminko

[jim d]

I would look at a parts book or service manual and see what it is there for. I am no sure which screw that you have removed but do some research before that you remove anything else.

[slamiste]

Hi Jim,
The screw I removed holds something called the "oil channel" inside the transmission. A BMW buddy of mine says it directs oil splash to a part of the trans assembly.
It seems there's only one screw holding the channel in place and since I removed it, the channel is loose somewhere inside the trans. For better or worse I've started the transmission removal process. The bike has over 70,000 miles on it so a look see at the clutch and other hidden parts would seems worthwhile.

A few years ago my MotoGuzzi 850T3 had a broken shifter return spring that required a transmission removal. In the process, I discovered the U-Joint for the shaft drive was ready to fail badly at any time. I think the failure would have caused some big damage and likely would have resulted in a crash.

So I'm going to go with the "it's a good idea to remove the transmission as a preventative measure" to make me feel better about removing that darn screw BEFORE researching what it did.

Thanks for your help!

Steve

[jim d]

Spring

I would suggest that you replace the shifter springs in this transmission also. Looks like you removed the oil baffle retaining screw.