| Also known as | T3929 |
| Diagram | Fig. 14 — CLUTCH · ref 2 |
| Subsystem | primary |
| Listed in parts books | 1970–1972, 1974, 1976–1980, 1983, 1985 |
CLUTCH HUB 650/750 1970-83 Replaces 57-1734 68-3277
Clutch hub for 650/750 unit twins, 1970-83, replacing the earlier 57-1734 and 68-3277 hubs.
The 57-3929 is the clutch hub, the center piece that the clutch plates stack onto inside the primary chaincase. It's a gearbox-side part that shows up in the parts books under CLUTCH and GEARBOX OUTER COVER, which tells you it lives right where the clutch assembly bolts up to the transmission mainshaft, splined so the whole clutch pack drives together.
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This number replaces the earlier 57-1734 and 68-3277 hubs, and shows up in the catalogs across 650 and 750 twins from 1970 into the later '70s. If your parts book still lists the old T3929 or T3931-era numbers, this is the current equivalent you'd be ordering. Older pre-unit and early unit applications sometimes call for pairing this hub with a separate thrust washer, so if you're working on something outside the 1970-83 window, check what washer your specific clutch pack needs before you bolt it up.
We don't have more detail than the catalog entries above, but this is a straightforward, well-documented part in our system. If you're not sure your bike's clutch setup matches this hub, call the shop and we'll walk through it with you before you order.
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