This photo and the accompanying tables illustrate the differences between the gears of the mono and early R50, R60 gearboxes and the later /2 type gearboxes.
The lower-ratio gears from the early gearboxes are sometimes installed in later gearboxes for sidecar use, as they provide improved low-speed control and increased pulling power. Conversely, the higher-ratio 1st through 3rd gears are often fitted to reduce engine speed in these gears, resulting in more relaxed cruising and smoother operation at higher road speeds.
Although the 3rd gear of both gearboxes have the same number of teeth, they are different:
The standard gear has a diameter of 65.6 mm and the S-type gear has a diameter of 65.2 mm.
They have a different profile deflection. The S-gear is marked with a green dot, for easy identification.
