One point about the rope seal...when your crank is banging up/down, it is hammering the rope seal into the groove constantly. And it isn't just the rear bearing...all the main bearings need to be as tight as possible since there are only 4 and motion in others will transmit motion front/back. This is one thing that causes the rope seal not to seal as well. Back in early college days a friend and I had the idea what was needed was something that could be inserted in the middle of that rope seal which would be elastic in nature. In other words, a core that had spring-like ability to keep the rope pushed constantly against the crank surface. But we never did figure out just what it would be...and as far as know neither has anyone else. Once the rope seal gets hammered down and slick from motion, it just won't seal well anymore. Granted this isn't a pressure seal, but the radical angle of the 235 ensures oil will be always present at that area.
