| Also known as | E5157 |
| Diagram | Fig. 34 — SPEEDOMETER AND TACHOMETER · ref 14 |
| Subsystem | electrical |
| Listed in parts books | 1966–1971, 1974, 1976–1980 |
Driving gear
The driving gear inside the tachometer drive gearbox on unit-construction Triumph twins.
70-5157 is the driving gear from inside the tachometer drive gearbox on unit-construction Triumph twins. It's a small precision-cut gear that meshes with its mating pinion to turn the tach cable at the right ratio, and it lives inside the gearbox housing that bolts up to the drive point on the engine. If the tach needle jumps, flutters, or stops reading altogether, a worn or chipped tooth on this gear is one of the usual suspects.
Read more
The catalog also lists this part under the older E5157 number, so if your parts book or an old invoice shows that instead of 70-5157, you're looking at the same physical gear.
This one shows up across catalog entries spanning 1966 into the mid-1970s, so it's worth checking your specific gearbox housing and gear ratio before ordering to make sure it's the correct mesh for what you've got.
Sorry if we got something wrong here. If you think this information isn't correct, .