| Also known as | M11121, T1606 |
| Diagram | Fig. 2 — CRANKCASE · ref 11 |
| Subsystem | gearbox |
| Listed in parts books | 1964–1974, 1976–1980, 1983, 1985 |
Needle roller bearing, layshaft
Closed-end needle roller bearing for the gearbox layshaft on unit-construction Triumph twins and triples.
57-1606 is a needle roller bearing that fits into the gearbox layshaft, one of the shafts that carries drive through the box between mainshaft and output. It's a closed-end style bearing, meaning it's built to seal off one end rather than run straight through, which matters when you're figuring out which of the layshaft bearings you're replacing versus 57-1614 or others in the same assembly.
Read more
This one shows up across a long run of gearbox figures in our records - crankcase, gearbox shafts and bearings, inner cover and selectors - so it's a bearing that gets specified whenever someone's rebuilding the shaft train rather than just swapping seals. The older book number for this part is T1606, and it's also cross-listed as M11121 if that's what's stamped in your paperwork.
If you're pulling the gearbox apart for a rebuild, worth checking the mating layshaft and the inner cover bearing bore for wear at the same time - a tired bearing here is usually a symptom of a shaft or housing that's seen a lot of miles, not just a standalone part failure.
Sorry if we got something wrong here. If you think this information isn't correct, .