| Diagram | Fig. 3 — CRANKCASE · ref 71 |
| Subsystem | primary |
| Listed in parts books | 1969–1972 |
BSA Fibre washer, rear chain oiler (1/4" × 17/32" × 5/64")
A 1/4 in. x 17/32 in. x 5/64 in. fibre sealing washer used in the rear chain oiler oil feed line.
66-7518 is a small fibre washer used in the rear chain oiler setup. It's a flat sealing washer, sized 1/4 in. x 17/32 in. x 5/64 in., that sits in the oil feed line running to the rear chain.
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It shows up in the parts book alongside the crankcase and primary chaincase/clutch cover figures, which is where the oil feed for the rear chain is plumbed off the engine. Fibre washers like this one are used to seal a banjo fitting or union in an oil line without crushing or scoring the mating faces the way a metal washer might.
It's a cheap-to-replace item that's worth having on hand any time you're pulling apart the primary side or chasing an oil leak at the rear chain oiler feed. The catalog record spans several appearances from 1969 to 1972, but check your own parts book listing to be sure it's the right washer for your rear chain oiler union before you order.
We've never carried this one. Tell us what you're after and we'll go looking — you'll get a price and photos before you commit to anything.
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