TRAPDOOR

First seen on the 1954 K model, the removable plate behind the clutch on the left side of the gearbox gives access to the internals without splitting the crankcase. It can be removed along with the shafts and selector mechanism as a complete assembly. It’s a precursor of the cassette gearboxes commonly used on modern road racing machines for quick changes to internal ratios. In pre-1980 XL boxes, however, uncaged rollers in the right-side mainshaft bearing can make assembly a long and fiddly job.

This plate allows access to Harley’s precursor to the cassette gearbox