I’ve removed the airbox, transmission, clutch and flywheel to gain access to the rear main seal so I can replace it. You can see how I did that work here.
- 13 BMW 1983 R80ST Remove Air Box & Pulse Air System
- 23 BMW 1983 R80ST Remove Transmission
- 21 BMW 1983 R80ST Remove Clutch
- 11 BMW 1983 R80ST Remove Flywheel
I’ve published documents on replacing the rear main seal on other projects. Here are links to those documents.
- 11 BMW 1983 R100RS Remove Flywheel & Rear Main Seal
- 11 BMW 1983 R100RS Install Rear Main Seal, Oil Pump Cover & O-ring
- 11 BMW 1977 R100RS Replace Rear Main Seal & Oil Pump Cover O-Ring
- 11 BMW 1975 R75/6 Replace Crankshaft Rear Oil Seal, Oil Pump Cover & O-ring
- 11 BMW 1973 R75/5 Remove & Install Flywheel, Replace Rear Main Seal, Oil Pump Cover & Cover O-Ring
Since the 1983 R80ST engine is similar in many ways to the 1983 R100RS, I link to the 1983 R100RS documents as appropriate in this document.
And here is a short YouTube video showing the procedure.
VIDEO: 1983 BMW R80ST Replace Rear Main Seal
I had a real problem removing the seal on this bike using my usual approach with the Cycle Works rear main seal tool, and had to resort to using “a bigger hammer”. I used a hook seal puller to pry the old rear main seal out of the bore. Since the bike has been sitting for 25-30 years, the seal was really stuck in the bore.