1973 R75/5 Rebuild: Remove/Install Flywheel, Replace Rear Main Seal, Oil Pump Cover and O-ring

I posted a new page on removing the flywheel, replacing the rear main seal, oil pump cover and cover o-ring and installing the flywheel. This also covers a repair to a leak I found in one of the crankshaft flywheel bolt holes.

The work I did was guided by a lot of advice and web content shared by others who have gone before me.  I’d like to acknowledge folks who regularly participate on the BMW Airhead forum on Micapeak.  In particular, Tom Cutter who runs  Rubber Chicken Racing Garage and Bob (Snowbum) Fleischer who has a great technical library on all things BMW motorcycles, answered questions I posted on the Micapeak forum and in personal Email and phone conversations.  I also used web materials posted on  Duane Ausherman’s site.

Here a few pictures from the write up.

Make-do Engine Stand

Make-do Engine Stand

10mm Long Bolt in Alternator to Block Crackshaft

10mm Long Bolt in Alternator to Block Crackshaft

Flywheel Bolts out And Oil Leaking

Flywheel Bolts Out And Oil Leaking From Crankshaft Hole

Removing Oil Pump Cover with Impact Driver

Removing Oil Pump Cover with Impact Driver

Tightening Bolt to Pull Rear Main Seal

Tightening Bolt to Pull Rear Main Seal

Heated to 220 F

Heating Flywheel Bolt Circle to 220 F Prior To Installation

4 thoughts on “1973 R75/5 Rebuild: Remove/Install Flywheel, Replace Rear Main Seal, Oil Pump Cover and O-ring

  1. Brook,
    Thanks for the great documentation of your procedure, awesome!
    My bike is a ’76 R90S, and I am just assembling the parts to do a main seal replacement after having the transmission out for a rebuild, so I am learning alot from your experience. I do have a couple of questions on the procedure you used in putting the new main seal in. It looks like you fitted the main seal to the flywheel hub first to get it to fit properly. Did you then take the main seal off the flywheel and fit it to the crank? Then press the flywheel back into the main seal as you were re-attaching the flywheel to the crank?
    Thanks,
    Marty Nelson
    Seattle

    • Marty,

      Thanks for reading and posting the question. I did remove the new main seal off the flywheel hub after forming the lip. After I installed the seal with the Cycle Works tool, I mounted the flywheel on the crankshaft hub and pushed it onto the crank past the seal.

      I just updated the the write up to make that clear. Thanks for helping make the description more explicit.

      Best.
      Brook.

  2. Outstanding writeups! I’m thick in the middle of a resto of a ’71 R75 and I’m going through your articles with great interest. Thanks for the effort!

    J.

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