| Diagram | Fig. 7 — CLUTCH · ref 9 |
| Subsystem | primary |
| Listed in parts books | 1969–1972 |
BSA Primary cover screw, dowel hole (1/4" Unified Coarse × 1 7/8")
1/4 inch UNC dowel-hole screw, 1 7/8 inches long, for the primary/clutch cover.
This is a primary cover screw used to secure the primary chaincase cover, specifically at a dowel hole location. It's a 1/4 inch Unified Coarse thread screw, 1 7/8 inches long, made for holding the clutch/primary cover tight against the crankcase where a dowel keeps the cover aligned.
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The catalog data ties this one to the clutch and primary cover figures across several parts-book listings from 1969 to 1972, so it's a part that shows up consistently in that era's primary chaincase assemblies. If you're pulling a primary cover off a bike from that catalog window and need a replacement screw at the dowel position, this is the one the books call for.
As with any primary cover fastener, check the length and thread against what's already in the case before you order a full set — dowel-hole screws sometimes differ from the other cover screws around them.
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