JVB Productions
Motorcycle Maintenance and Repair Videos
2017 JimVonBaden/JVB Productions
Wethead Final Drive Lube and Fluid Service

Caution: This pictorial is for informational purposes only. I accept no responsibility for accuracy, or any damage caused to your motorcycle if you choose to perform these maintenance items.

While not part of the BMW Service Schedule, it is a good idea to do this at the 6 or 12 K service. This is especially true if you do a lot of deep water crossings, ride in the rain often, or just put on a lot of miles. There have been cases of corrosion in the FD on several bikes, though not a large number by percentage, and even a failure of the FD splines on one bike due to corrosion. So, with that in mind, I decided to check a 14K mile and 6K mile GSw today. Here are the results, and general how-to:

Pull the fender and wheel.
Then remove the speed sensor and the brake caliper:
Then hang the caliper out of the way:
Next remove the drain and fill plugs:
Then pull the bolt holding the Paralink bolt to the final drive:
Be prepared for it to drop down as you pull the bolt. Sometimes it doesn't and you will have to pull the final drive down. Make sure you have a cookie sheet or tray below the FD. You want no more than 1" deep for a tray. No worries about the amount of fluid, it will be fine.
Now you can see the condition of the splines, and the area inside the final drive. Both bikes looked exactly like this, and the 14K mile bike had a lot of off roading, presumably with water crossings. If you find oil in the swingarm, look up inside and see if there is an oil trail. If so, it will be the transmission output seal. If not, look at the dropped final drive for wet oil indicating a leaking final drive input seal.

Here are a couple of images of rust damaged Final drive splines and driveshafts:

Boxerbeat on ADVRider:
From micheallmcc on ADVRider:
BillGSA on ADVRider:
Time to lube the spline, even if they have lube. Use a Moly based lube like I did, any moly based paste will do:
No need to go nuts, a thin layer is fine.

Once done, the fun part begins. You need to install the gaiter and mate the final drive to the driveshaft. There are two tricks to it. First, install a soft wire into the driveshaft U-joint like this to hold it in position:
Second, if you are having difficulty, leave off the gator and fit the final drive. You will see it can be tricky. Use the big final drive hole to rotate the final drive to mate the splines. I hold the FD through the hole and rotate it like to mate the. Once mated, gently drop it down allowing the final drive hole to rotate back. Install the gator on the FD side in the clips, then lift it back up. It may take a few tries.
Once you get them to mate, install the Paralever bolt to hold it in place.
Once in place, press the gator clips into the swingarm and make sure it fits correctly. It is pretty obvious:
Once that is in place, install the paralever bolt all the way, then the final drive drain, then the speed sensor and brake caliper:
Then pop in 180ml of final drive gear oil.
Reinstall the wheel:
Install the fender, if you have one (3Nm with medium strength loctite) and you are done.

For more information, see this thread on ADVRider (Link)