| Also known as | T1931 |
| Diagram | Fig. 14 — CLUTCH · ref 19 |
| Subsystem | primary |
| Listed in parts books | 1964–1971, 1974, 1976–1980, 1983, 1985 |
CLUTCH SPRING CUP TRI/BSA
Steel spring cup that seats the clutch springs in Triumph and BSA clutch assemblies.
57-1931 is the clutch spring cup, a small steel cap that sits under each clutch spring inside the gearbox outer cover housing on Triumph and BSA clutch assemblies. It gives the spring a proper seat to bear against so pressure stays even across the clutch plates. This part shows up across a wide run of catalog years, which tells you it was a common fitment across a lot of different unit and pre-unit clutch setups rather than something tied to one specific model.
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The old book number was T1931 before the modern numbering came in - same physical part either way. It's a cheap thing to overlook when you've got the clutch apart, but a tired or distorted cup can throw off spring pressure on that spring, so it's worth a look any time you're in there for plates or springs.
These cups get replaced a few at a time depending on how many springs your clutch uses, so check what your hub takes before ordering.
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