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.

• 33 BMW 1983 R80ST Rebuild Rear Drive

I replaced the swing arm bearings and you can read about how I do that here.

• 33 BMW 1983 R80ST Replace Swing Arm Bearings

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.

• 33 BMW 1983 R80ST Install Swing Arm, Rear Drive, Monoshock

VIDEO: 1983 BMW R80ST Install Swing Arm, Rear Drive, Monoshock

Here are some before and after pictures.

Here is the R80ST with the swing arm, rear drive and monoshock installed. It’s starting to look like a real motorcycle again. 🙂

 

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.

• 33 BMW 1983 R80ST Rebuild Final Drive

Here are some before and after pictures.

 

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.

• 23 BMW 1983 R80ST Remove Transmission
• 23 BMW 1983 R80ST Disassemble, Rebuild, Assemble Transmission

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.

• 23 BMW 1983 R80ST Install Transmission

VIDEO: 1983 BMW R80ST Install Transmission

Here are the before and after pictures of the transmission.

 

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.

• 34 BMW 1983 R80ST Rebuild Front Brake Caliper

Here is the description of how install the front brake and a summary YouTube video of how I do this work.

• 34 BMW 1983 R80ST Install Front Brake

VIDEO: 1983 BMW R80ST Install Front Brake

The 1983 R80ST has a single front disk brake on the right side of the front wheel. It uses a Brembo caliper connected to a master cylinder and fluid reservoir built into the right handlebar control unit.  I repainted the caliper using black caliper paint.

Here is what the caliper looked like when I got the bike removed it from the bike.

And this is how it looks after repainting and rebuilding.

This shows how I do the work.

• 34 BMW 1983 R80ST Rebuild Front Brake Caliper

Here is a short video summarizing the procedure. It is a mix of video from the 1983 R100RS and 1983 R80ST.

VIDEO: 1983 BMW R80ST Rebuild Front Brake Caliper