| Diagram | Fig. 13 — GEARBOX OUTER COVER · ref 8 |
| Subsystem | gearbox |
| Listed in parts books | 1974 |
| Also fits (as replacement) | 1972–1973 · for T4374/408 |
GEAR CHANGE QUADRANT,5 SP
Gear change quadrant for the 5-speed right-shift gearbox on unit 650/750 Triumph twins.
The 57-4910 is the gear change quadrant used in the 5-speed gearbox, the part that translates movement from the gear change shaft into the selector mechanism that actually moves the gears. It's a wear item — the quadrant teeth and pivot see a lot of use every time you shift, and a tired one can leave you with sloppy or inconsistent gear changes.
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This quadrant is built for right-shift 5-speed gearboxes on the unit 650 and 750 twins. It also comes up when someone is converting an earlier 4-speed unit or pre-unit gearbox over to 5-speed internals, since the quadrant is one of the pieces that has to be right for the 5-speed shift mechanism to work correctly.
If you're rebuilding a gearbox and the shifting has always felt vague or has gotten worse over time, this is a good place to look. Worth checking the mating parts in the selector mechanism at the same time since wear here often shows up alongside wear elsewhere in the linkage.
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