Originally Posted by Bluethumb
What can I do to lower r.p.m.'s of a ST? At hiway speeds of 70 m.p.h., the engine is spinning about 1,000 more r.p.m.'s then my R100. I know of two ways to change the ratio of the final drive on a G/S - ST. One is with the higher 5th gear and the other is the optional final drive. The higher 5th gear is expensive from what I've read, the cost of the gear plus the time and expense of a rebuild. I thinK I've read it drops r.p.m.'s by 400-500. The optional final drive is NLA I believe, but if it is still available I'm guessing it's unbelievably expensive and I'm not sure how much it drops r.p.m.'s.
Is there another option? Is it possible to use a different FD and re-lace the rear hub to a ST rim?
Any other way to replace the final drive with another to drop engine speeds?
There is a solution that hasn't been mentioned yet: the adaptation of a 88-95 RxxGS rear wheel to a monolever 4-lug FD. That gives you three FD ratios from factory:37:11 (R80RT Mono), 32:10 (R100RT Mono) or 33:11 (R100RS Mono) . Details are here: http://www.stephenbottcher.net/BMW/rearconv.htm
Hope that helps, Stephen