Economy Gear Primary Late 1300 30 Tooth

Assembling the engine to gearbox (transmission) is explained and simplified in this article. Contrary to popular mis-guidance, all BBUs will fit all four-syncro gearboxes. It was only the three-syncro boxes that varied in casting dimensions causing hassles where 1275s were applied to 850/998 gearbox casings. The longer throw and bigger crank and rod assembly dimensions fouled the sculpted areas in the gearbox case,

The standard drop gears are fine for practically all road use - almost irrespective of power output. Despite what many folk believe - they are more than strong enough, and will perform perfectly well if correctly set up. That means getting the idler and primary gear end floats right, and using new bearings for the idler gear at each re-build.