Transmission Breather grease weepage - cause???

[Sunbeemer]

A small amount of lubricant (I suspect is tranny gear oil) has weeped out of the breather vent on top of the transmission (under the airbox).
That's item # 4 in the diagram at http://www.realoem.com/bmw/showparts.do ... g=23&fg=05

I changed the tranny (and FD) gear lube in June and hadn't noticed any leakage until I just saw the greasy smudge running down the side of the gear case. While cleaning that I noticed the vent cap is moist with oil and there was also a greasy smudge running along the top of the tranny back to the clutch slave cylinder (but it's not coming from there) so it might have been leaking for a while and I just didn't notice it.

Anyway, what do you think might cause this? Could cooler weather and thicker grease have anything to do with it?

With regard to overfilling (since that would be the obvious cause), my Clymer's and BMW manuals disagree about whether 'tis better to fill the tranny (and the FD) on the sidestand or the centersatand. So, what do you do -- fill the tranny and final drive with the bike on the sidestand or centerstand?

[boxermania]

Interesting!!!! It could be overfilling, if done on the sidestand and some of the oil is being slung by the rotating gears in the direction of the breather. There should never be any oil coming out of the breather, unless you park the bike upside down....just a bit of levity..

Tranny and FD drive service should be done on a level surface and on the center stand. The oil level should be brought to the bottom of the threded plug. Check the oil levels and adjust as required.

Good luck

[Phang]

I read somewhere that using a too high viscosity gear oil or too low ambient temperature will lead to an oil spewing breather.

The gear oil gets flung around in the box when it is cold and thick, coating and blocking the breather from inside. When the gearbox/FD is gradually warming up, the expanding air inside is pushing the gear lube through the breather.

[boxermania]

Phang

It looks like the pads on that rear caliper might be draging on the rotor a bit too much. Have you checked to see how free the wheel turns????

[Phang]

The bike in the photo is not mine, I found it in Adventure Riders via Google

[Sunbeemer]

Thanks, guys, for the responses. That must be Redline Shockproof in that FD! I use Castrol Hypoy-C 80W-90 weight gear oil in both tranny and FD. I'll check the level and probably change it after things settle down from the holidays!

Speaking of...the best of which to you!