| Also known as | T3958 |
| Diagram | Fig. 9 — OUTER PRIMARY COVER – CHAIN TENSIONER – CLUTCH CONTROL · ref 42 |
| Subsystem | primary |
| Listed in parts books | 1971, 1973 |
Outer cover – complete assembly
Complete outer primary chaincase cover assembly, catalog number 57-3958 (formerly T3958).
This is the outer primary chaincase cover, part number 57-3958, sold as a complete assembly. Older parts books list it under T3958, the same physical piece under the pre-decimal numbering. It shows up in the catalog under the outer primary cover, chain tensioner, and clutch control figure, along with the inner and outer chaincase figure, so it's the outer half of the primary chaincase housing that closes over the primary chain, alternator, and clutch assembly.
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The outer cover is what you pull off when you need to get at the primary chain to adjust or replace it, service the clutch, or check the alternator stator and rotor. It bolts to the inner chaincase half and seals the whole primary drive against road dirt and keeps the chain oil bath contained.
Our catalog record ties this to appearances across 1971 through 1973, but we'd rather have you confirm exact fitment against your machine before ordering rather than guess off a year span alone. Give the shop a call if you want us to check it against what you're running.
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