Here is a photo essay of sorts detailing the disassembly of a 1973 BMW Final drive. The same applies to all 1970’s era BMW’s (R90 R100 R75 R80 /5 /6 /7 S etc). The seals were shot inside causing leaks. The splines are decent so no need to weld on a new set of splines. I plan to have the drive blasted and powder coated to match the rest of the bike for an upcoming build.
The image descriptions have notes on the disassembly.
I can’t remember the condition of this final drive when I assembled my 77 R100s back in 2003. When I had my rear tire replaced recently, I noticed how terrible the splines are. The splines on the wheel are better then the final drive but they will need replacing someday too.
I found this drive with the same ratio and cleaned it up and replaced the spline. Now it is time to swap the drives.
While it is apart, I am taking the opportunity to pull the tranny back and lube the clutch splines as well.