| Diagram | Fig. 10 — CLUTCH AND PRIMARY COVER · ref 19 |
| Subsystem | primary |
| Listed in parts books | 1970 |
BSA Clutch spring cup
A clutch spring cup that seats one of the clutch springs inside the primary cover.
57-3951 is a clutch spring cup, one of the small cupped washers that sits under each clutch spring inside the primary cover. It shows up in the catalog under the CLUTCH AND PRIMARY COVER figure, so it lives right where the clutch springs bear against the pressure plate or clutch body.
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The cup gives the spring a proper seat to push against and keeps it from wandering off-center as the clutch is loaded and unloaded. It's a small part, but a bent, cracked, or missing cup can throw off spring pressure at that point and cause uneven clutch engagement.
Our catalog record only ties this one to a single model year, so if you're matching it against an older parts book, give us a call and we'll confirm it's the right cup for your primary cover before you order.
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