| Also known as | E1580 |
| Diagram | Fig. 1 — CRANKSHAFT AND CONNECTING RODS · ref 25 |
| Subsystem | engine bottom |
| Listed in parts books | 1960–1962, 1964–1971, 1973–1974, 1976–1980, 1983, 1985 |
CRANK KEY TIMING PINION
The woodruff key that locks the timing pinion to the crankshaft on Triumph twins.
70-1580 is the woodruff key that locates the timing pinion on the crankshaft, keeping it from spinning relative to the crank as the engine turns over. It's a small, unglamorous part but it does real work, transmitting drive from the crank to the timing side gear train and holding the pinion in correct alignment. The catalog lists it under the CRANKSHAFT AND CONNECTING RODS figure, and it shows up across a long run of catalog years from the mid-60s into the late 70s.
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You'll also see this part referenced under the numbers 98490A190 and E1580 depending on which parts book or supplier list you're working from - all three point to the same physical key.
Because it sits right in the crank-to-pinion joint, fit and condition matter more than the price tag suggests. A worn or sloppy key here can let the pinion work loose over time, so if you're rebuilding the bottom end this is worth replacing rather than reusing if there's any doubt about its condition.
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