Originally Posted by Airhead Wrangler
You want to keep the u-joint of the driveshaft in the same spot vertically that it was before. The driveshaft is free to move up and down on the front end, but at the back the splines in the final drive are fixed. If you move the driveshaft forward or backward, up or down, you're changing the axis of the driveshaft in relation to the rotating axis of the final drive input spline. The only way these two can remain coaxial throughout the suspension travel is if the u-joint at the front of the driveshaft is directly inline with the pivoting axis of the swingarm. Not watching out for that will result in undue wear on your final drive input and drive shaft splines. Since the whole mess is drenched in gear oil, the wear probably wouldn't be that rapid though.
Good points I had not concidered.The drive shaft is bolted up to the gearbox flange as per normal, its the other end that has its overlap reduced.
But yes the u joint is no longer is sync with the swingarm.
It is however more lined up than the stock set up.......ummmmm
The reality for my bike is that it only does not do a lot of miles per year.
I was wondering if as its a race bike am I losing power churning all that EP 90 around in the box and FD.....could I go to lighter oil?