You might have water contamination in your oil. I've seen that cause blow-out.
Not normal, and there's no baffle in those. Monolevers got a baffle.
Kurt -- Forum Liaison ---> Resources and Links Thread <---
'78 R100/7 & '69 R69S & '52 R25/2
mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!
The oil was clearly coming from the vent cap. Maybe i was just traveling too fast for too long.
I called Bobs BMW and told him how i filled the final drive and they agreed i did things correctly. It started out the trip at the proper fill level.
Pics of some other bike are not going to allow us to help diagnose what might be going on with your bike.
again, this is NOT a common problem, so seeing YOUR bike might give us some clues as to what is happening.
Ride Safe, Ride Lots
Here is my final drive.
Is it possible that you have recently changed the brand or type of oil in the rear drive?
Did the venting problem start with this trip having been ok in the past or is this a new bike to you?
You say you used 80w90 gear oil - that is correct as I understand but the reason for my asking above is
that once in the past on an earlier year airhead I thought I could slow or cure a leaking drive seal problem
by using 85/140 gear oil instead of the 80/90 - the result was that the thicker oil was thrown up to and out
the vent like the problem you describe - my experiment failed and made a mess
The type or brand of the oil you used may be an issue if you have changed just prior to this problem.
Same oil since i bought the bike 5 yrs ago, 20k miles, valvoline durablend part synthetic, 80w90. The vent has always done this, the more close to full the worse the blow by through the vent which is also tied directly to speed. I could have it full and ride around all day at 40 mph and just get a little oily wetness around the vent cap. If the oil level is 1/2 or more below the 9:00 bolt hole i could ride all day at 70 mph and see the same. If it's full and i ride at 70 it wants to blow oil all over. Could someone post a picture of the inside of their vent cap? I'd like to compare it to what i had. I've welded a baffle in mine already otherwise i'd post a picture of mine.
same thing happened to my '74 900. Conditions, cool temps, just changed from BMW gear oil to Dino Valvoline 80/90, went for short spin, came back foamy oil all over the place oozing out breather top. Panic. What I remember is advice concerning how at a times, when conditions are right, the gears can shear air bubbles into the mix creating greater volume then housing contains, there's nowhere for the frothy mix to go except out the top. There was a thread explaining all this back in the lost threads somewhere, around aught eleven. I now use BMW gear oil with a pinch or two of moly. Inner seal has just started a infinitesimal leak, another project. Two cents FWIW.
I checked and resealed a finned or '80 and up F/D similar to the OP and found a sheet metal baffle plate inside that appeared to be there to direct the oil splash away from the vent. Mine has never pushed oil out the vent.
Not if you can see the gears, but I checked one earlier this morning and it (an '82 FD that did not have a baffle) certainly accepted a baffle from a later FD. Maybe some of them are just missing?
Now we are getting somewhere. There is definitely no baffle inside my final drive.
Went out for a ride today. Vent cap puked oil all over the place. I called max bmw and talked to rusty about my issue. I took off the rear wheel and the oil was not coming from any of the seal. Rusty said there is supposed to be a baffle inside the final drive and if i can see the crown gear rotating mine is missing. I'm going to hook up a puke line with a banjo fitting while i wait for the baffle to arrive from Germany. Why it has never done this before i have no idea.
I did check the fluid levels when i returned home. Driveshaft was right on, final drive was 100 cc low. Ride was about 80 miles.
good perseverance. a definite odd-ball "wow".
Ride Safe, Ride Lots