So from our previous entry, we saw that the stock R75/5 clutch components were not up to the power of the hopped up, high compression, hot cammed Reg Pridmore engine.

How to get a clutch designed to deal with more grunt? Not as hard as one might think.

The stock 1973 engine put out 50HP and 44 ft lb of Torque. But using the same block, in 1973 to 1976 BMW built the sporty R90S with 67HP and 56 ft lb of Torque. After doing some research, I found that BMW designed a heavy duty clutch, which is still available for the R90s and later bikes, and that it would all fit on my bike, without modifications. Below are comparison pictures of the old and new parts, click to enlarge…

New clutch, pressure ring and pressure plate

New clutch, pressure ring and pressure plate

old and new pressure plate face

old and new pressure plate back

Note the new clutch plate has 2x the rivets

Note the new clutch plate has 2x the rivets

Note the new pressure ring is a LOT more beefy than the old one…

old and new pressure ring

New and old pressure ring….

Up Next: Yank My Flywheel!

https://kirkusblog.com/2011/02/23/das-bike-projekt-motorbike-archeology/