| Also known as | T3940 |
| Diagram | Fig. 14 — PRIMARY TRANSMISSION AND OIL PUMP DRIVE · ref 11 |
| Subsystem | engine bottom |
| Listed in parts books | 1969–1974 |
Bolt – shock retaining plate (2 B.A. X 5/8")
A 2 B.A. x 5/8 inch bolt that secures the shock retaining plate on the clutch shock absorber assembly.
57-3940 is the bolt that holds the shock retaining plate on the clutch shock absorber assembly, part of the primary transmission on unit Triumph twins. It's a 2 B.A. bolt, 5/8 inch long, and it shows up in the parts books under the older T3940 number as well. The shock absorber sits in the clutch center and cushions the drivetrain from sudden loads, and this bolt is what keeps the retaining plate clamped down over it.
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This one lives inside the primary chaincase, behind the clutch, so it's not something you see unless you've got the cover off and the clutch apart. Catalog listings put it across a run of years from 1969 into 1974, showing up in both the primary transmission and oil pump drive figure and the clutch shock absorber figure.
If you're rebuilding a clutch shock assembly it's worth checking these bolts for wear or stretched threads rather than reusing tired ones. Bring in the old bolt or your parts book reference if you're not sure which fastener you need — there's more than one small bolt in that area of the engine.
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