| Also known as | T1607 |
| Diagram | Fig. 11 — GEARBOX INNER COVER AND SELECTORS · ref 5 |
| Subsystem | gearbox |
| Listed in parts books | 1964–1974, 1976–1980, 1983, 1985 |
THRUST WASHER,LAYSHAFT - TRIUMPH 500/650 UK (LF Harris) For USA use 57-1607P
Bronze layshaft thrust washer for the Triumph gearbox, used in pairs to control layshaft end float.
57-1607 is the layshaft thrust washer used in the Triumph gearbox, sitting inside the inner cover area where the layshaft runs. It's a bronze washer whose job is to take up end float and keep the layshaft properly located against its bearing surface as the gearbox works. The catalog shows it appearing across gearbox inner cover, selector, and shaft/bearing figures from the mid-1960s into the late 1970s, spanning the 500 and 650 twin gearboxes used through that run.
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The legacy book number for this one is T1607, so if you're working from an older parts book and see that reference, it's the same washer. Triumph parts books also flag a USA-specific version, 57-1607P, so before you order double check which of the two your gearbox actually calls for rather than assuming they're interchangeable.
Because it's a bronze wear item down inside the gearbox, it's not something to skip replacing just because it looks serviceable — a gearbox rebuild is the natural time to put a fresh one in. Since two are used per gearbox, plan on ordering a pair rather than a single washer.
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