2015 GSA Final Drive Repair ..... Info for Others
 

Hi All,
Just thought I'd post some photos and info for a recent repair to our Final Drive so others may benefit... even just a little bit.

We are travelling South America and have 70,000Km on our 2015 GSA that we bought brand new. I noticed that there was indication of weeping oil on the final drive Shaft Seal 33758529957 so I replaced this with no issue and it only took 5 minutes. I simply lay the bike on its side so I didnt loose any oil form the drive. A week later I noticed indication of oil on the Rubber joiner part (what ever its called) which connects the drive to the drive shaft section. I suspected the small shaft seal (inside the drive) 33758529959 but I also had concerns it may have been the Universal joint on the way out. Anyway we bee lined to Medellin and I dropped the final drive..... the photos should indicate what I found..... basically a lovely mixture of water/ oil and rust. We pulled the drive shaft out...... universals OK. but the splines were as dry as a &*^% I cleaned it all up as shown, put some copper grease on the splines, replaced the seal and reassembled. I have also drilled a small hole in the drive shaft case to allow any future water to escape. We are not Starbucks riders and the bike is regularly in water as we travel the back roads. Now I had my hesitations and I'm sure there are a few of you saying...... you did what, because not only will it let water out...... it will also let water in!!!.
Look i'll monitor the situation and if I find it doesnt solve things then i'll simply silicone up the hole but from what I found it looked as though there had been water trapped in this area for along time now and I'd rather have it drain away.
I hope someone gets some info from all this

Thanks for the post, good to know that's a potential issue! You can also find "one-way valves" made of rubber, often used in for instance the old airhead airboxes, to so water can get out but it doesn't suck in water. Might be a place here for that.

:stupid:

It also helps you keep an eye on how much water is still kreeping in.

"I have a dream" That one day bmw makes a trouble free final drive! bier

:mchappy:

For all you fans who like to ride through deep water here is a fix you might consider .
First though my take on the reason why you get water trapped inside the driveshaft housing . Apparently it does not have an air vent and the rubber seals at the ends are doing a good job - or failing miserably - of sealing .

In either case so much water is getting in because you are driving through deep water with a hot bike . When the water covers the driveshaft it will immediately cool the drive shaft housing and cause the air inside to also cool rapidly . This makes the contracting air inside the housing act like a vacuum pump and suck in water through whatever gaps are available .
It is better to have a good sized vent fixture connected to a plastic tube which has its upper end below the seat , at a level which never gets submerged .
I suspect that the bevel gear housing and the transmission, both with vents , may also be drawing in water at times if submerged . .

The drain hole fix is okay but it too will also ease the rapid intake of water.
Might want to put a rubber plug in it and drain after each water crossing .

Unrelated , but a good example of this pumping effect is with empty steel drums with the caps on but not sealing properly and left outside in the weather while standing upright . The sun shining on the drums will heat pressurize the air and expel it . If a cloud comes across the sun the air cools and the drum begins sucking in replacement air .If it begins to rain the cooling off is greater and the collected rainwater on top of the drum gets drawn inside . Left long enough the drum will eventually fill with water .

I have dream too BMW one day will make R1200GSA with regular swing arm and chain bier

They do..... Its called a Multistrada Enduro :innocent: