The gearbox casing on this bike is an extra strong one by Cal products, the bottom is shaped so it fits in the rectangular openings in the transmission plate. This allows the gearbox to move in a straight line only, so the belt is always aligned correctly. This casing also has a threaded boss for an adjuster screw so I modified the transmission plate by welding on a 3/8" strip. Now adjusting the belt will be a lot faster and easier!

As you can see the mainshaft of the gearbox has been leaking oil so the next modification will probably be to fix this. Also I don't really like the 3" beltdrive, and think I will replace it with a more narrow one.