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.
A 1978 BMW R100s fixed up and released back into the wild.
This bike is an absolute dream to ride. It runs amazingly smooth.
I had to go through some serious DMV hoops to get the salvaged title status back on the road with a deadline of 5 months until I incurred DMV penalty fees. I made it to the registration day with 2 days to spare.
I cleaned, restored, replaced, rebuilt whatever it needed to get it back on the road. The front end is from a spare R90/6 that I had lying around.
This is one of those things I try to do to every BMW motorcycle I rebuild.
This area is cracked on nearly every frame I tear down. It is the rear foot brake area which also is the muffler / silencer hanger, and where the passenger foot pegs attach. This frame is a 1978 BMW R100s. If you are considering rear sets on your bike that attach to this section, then I HIGHLY RECOMMEND doing this procedure.
cracked tab near rear foot brake pivot hole on BMW airhead framecracked tab near rear foot brake pivot hole
cracked tab near rear foot brake pivot hole on BMW airhead frame
New piece of metal to weld onto the old cracked section to reinforce the area making it MUCH stronger and no longer prone to cracking.
Welded metal onto the rear foot brake section of a BMW R100S
Finished powder coated frame with the welded metal. This area is out of sight to most people unless they take the rear tire off.
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.
Just an update… I have 3 bikes in the works but they have been taking longer then expected. I’m trying to customize many features vs buying the available parts out there.
And, I’ve been busy over at Oshmo.com helping to develop some Airhead aftermarket parts that look good, and function, for customizing these old BMW’s.
Recent additions are rear sets, and top clamps… more ideas to come!!
A friend turned me onto the idea of having those old, nasty nuts and bolts cad plated.
After disassembling 4 BMW motorcycles over the years, i developed a few ziplock bags of rusted, filthy, oxidized junk.
After i gathered everything up in a tupperware container, it weighed close to 50 lbs.
I should have had this done before my latest restoration but nothing will beat the stainless steel hardware I have used throughout the bike.
This will, however, save me lots of money and trips to the hardware store.
It was a heavy load for one saddle bag. My bike was all over the road having ‘dead weight’ on one side of the bike.
These were pretty much un-usable parts. I threw in some fork plates, rusted axles, and other bits just to see what would happen. Whatever was aluminum couldn’t be plated but they got blasted clean anyway.
A day later and $80 out of my pocket and into the pocket of the guy who did this ‘under the table’ and this is what I got.
I spent about 3 hours watching TV, drinking beer and organizing everything. I would have been watching TV and drinking beer anyway…
And at anywhere from $.07 – $.60 per washer, bolt, nut and screw from the hardware store or from BMW (some parts are $2 or more), I think just the contents of this container is worth it.