| Also known as | 97-0310A, H310A, T4200 |
| Diagram | CLUTCH AND PRIMARY CHAINCASE |
| Subsystem | primary |
| Listed in parts books | 1971 |
CLUTCH HUB B25 B44 T25-70
Clutch hub for the BSA B25/B44 singles and the 1971 Triumph TR25W, also known by the older T4200 number.
This is the clutch hub listed in our catalog as fitting the BSA B25 and B44 singles, and it also shows up in our Triumph parts books for the Triumph 250 TR25W from 1971. It carries the older T4200 designation as well as the 97-0310A and H310A forms, so if you're working from a vintage parts book under one of those numbers, this is the same physical piece.
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It lives in the clutch and primary chaincase assembly, where it carries the clutch plates and takes the drive off the engine sprocket through the primary chain. Our books don't give a BSA-specific year range for this part, only the Triumph TR25W tie for 1971.
Because this hub crosses between two marques and a handful of part-number eras, it's worth double-checking against what's actually on your bike before you order, especially if your parts book lists a different alias for it.
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