Doug…. What’s your feelings on oil relief holes in the drums (help evacuate fluid/centrifugal weight)? Both of my older Lofgren builds had them including the 904 I’m currently beating on.
B&M found a decrease in parasitic loss in first gear with the holes.
In 1st gear, the front clutch retainer turns at 80% of the input shaft speed
in the opposite direction, so this means that the released clutches see a surface speed of 180% of input shaft speed; the trapped fluid in the drum creates lots of parasitic drag so drilling peripheral holes allows the trapped fluid to escape. I drill 3/16" holes in a staggered row.
Nowadays, lots of builders place small pieces of rubber tubing between the disc floater ears to help keep the discs separated but the trapped fluid is still there with no place to go.
