The rear brake on the 1983 R80ST is a drum brake.
Here is a link to the documentation and a short YouTube video summary of how I do this work.
VIDEO: 1983 BMW R80ST Install Rear Brake
Here is the final product.
All Done
All Done
I had the rear drive rebuilt by a friend of mine, Matt Iles, who owns Iles Motorsports and is a long time BMW mechanic. You can read about how he did this work here.
I replaced the swing arm bearings and you can read about how I do that here.
The R80ST has a monoshock rear suspension instead of the traditional dual shock suspension that was on all the other airhead bikes I have worked on. So the swing arm is a bit different. The procedure for installing the swing arm and rear drive on the 1983 R80ST is the same as for the 1983 R100RS.
Here is the link to the documentation and a summary YouTube video.
VIDEO: 1983 BMW R80ST Install Swing Arm, Rear Drive, Monoshock
Here are some before and after pictures.
Original Rear Shock
Original Rear Drive
Original Swing Arm, Rear Drive & Monoshock
Here is the R80ST with the swing arm, rear drive and monoshock installed. It’s starting to look like a real motorcycle again. 🙂
All Done
All Done
I suspect the final drive seals are leaking, and this bike has been sitting for about 25 years. So I am rebuilding and refinishing the rear drive. I have never rebuilt a rear drive before and I understand this requires some special tools and also correct shimming of the pinion and crown gear; aka, ring gear. So I asked Matt Iles, owner of Iles Motorsports, if I could watch him do this work, and he agreed. I have Matt replace all the seals and bearings in the final drive so it will be good for another 40 years and 100,000 miles. 🙂 That way I get an education about how this is done so I can decide if I am capable of doing this work in the future. Any mistakes in this documentation are on me, not Matt.
Here is the link to my documentation of Matt’s work.
Here are some before and after pictures.
Original Rear Drive Before Removal From Swing Arm
Rear Drive Case Before Vapor Blasting
Vapor Blasted, Rebuilt Rear Drive
Vapor Blasted, Rebuilt Rear Drive
Vapor Blasted, Rebuilt Rear Drive
After removing the transmission, I disassembled it, had the case and rear cover vapor blasted, rebuilt the shift cam assembly, input, intermediate and output shafts and reassembled the transmission. You can read about that work here.
So, now I’m ready to install it. I also install the clutch throw-out lever assembly, foot shifter assembly, clutch cable and speedometer cable. Here is a link to the documentation about installing the 1983 R80ST transmission and a YouTube video.
VIDEO: 1983 BMW R80ST Install Transmission
Here are the before and after pictures of the transmission.
Transmission Condition As I Found It
Transmission Condition As I Found It
Transmission Installed
Transmission Installed
The 1983 R80ST has a single front disk brake. The brake disk is mounted on the right side of the front wheel. This bike did not have the front disk, so I got a new one. I rebuilt the front brake caliper and you can see how I do that here.
Here is the description of how install the front brake and a summary YouTube video of how I do this work.
VIDEO: 1983 BMW R80ST Install Front Brake