| Also known as | T3999 |
| Diagram | Fig. 8 — GEARBOX SHAFTS, BEARINGS AND INNER COVER · ref 17 |
| Subsystem | gearbox |
| Listed in parts books | 1970, 1974 |
Layshaft Low Gear (27T)
27-tooth layshaft low (first) gear for the gearbox cluster, also known by its earlier part number 57-1950.
This is the layshaft low gear, a 27-tooth gear that lives on the layshaft inside the gearbox. It's part of the gear cluster that carries first gear duty, working in conjunction with its mating gear on the mainshaft to give you the lowest ratio in the box.
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Catalog records place it in the gearbox shafts, bearings, and inner cover section, with appearances spanning 1970 through 1974. The older factory number for this same part was 57-1950, so if your parts book or an old invoice shows that number, it's the same gear under its earlier designation. You may also see it listed under the legacy T-prefix form, T3999, which was how Triumph numbered it before the 57- system took over.
If you're rebuilding a gearbox and pulling the layshaft cluster apart, this is a good one to inspect for chipped or worn teeth along with its mating gears. Check the catalog or give us a call to confirm which years and boxes this particular tooth count belongs to before you order.
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