| Also known as | S1823 |
| Diagram | Fig. 2 — CRANKCASE · ref 29 |
| Subsystem | engine bottom |
| Listed in parts books | 1971, 1974, 1976–1980, 1983, 1985 |
Bolt, short - crankcase halves
Short bolt used to fasten the crankcase halves together on the unit-construction Triumph twin.
This is one of the bolts that clamps the two crankcase halves together on the unit-construction Triumph twin. The catalog calls it out as a short bolt in the crankcase fastener set, and it turns up across crankcase drawings from the mid-70s through 1980. It's a small part but it's doing real work holding the case halves square to each other around the crank and gearbox mainshaft area.
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When you're splitting cases for a rebuild, these bolts are worth checking over rather than just re-using without a look. Threads that have seen years of heat cycling and vibration are easy to nick going in and out, and a stripped or buggered hole in aluminum crankcase is a much bigger headache than a new bolt.
The alias number 91247A128 shows up in the records for the same physical part, so if your parts book or an old invoice lists that instead of 21-1823, you're looking at the identical bolt.
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