| Diagram | Fig. 15 — CHAINCASE AND CHAINS · ref 8 |
| Subsystem | primary |
| Listed in parts books | 1974, 1976–1980, 1983, 1985 |
TRUNNION,PRIMARY CHAIN AB
A trunnion for the primary chaincase tensioner assembly, part number 70-5087.
70-5087 is a trunnion used in the primary chaincase, part of the chain tensioner setup that keeps the primary chain running at the right tension. It shows up in the CHAINCASE AND CHAINS section of the parts books, and the catalog record ties it to a tie rod and tensioner arrangement rather than a standalone bracket.
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This is a small, unglamorous piece of hardware, but a worn or seized trunnion is the kind of thing that lets the tensioner blade sit crooked or bind up, which throws off chain adjustment. Given how it's listed alongside the tensioner and tie rod, it's worth checking these together when you're in the chaincase for other work.
Our catalog record for this one spans a run of years across several appearances, but we don't have a specific model or year pinned to it beyond that, so confirm fitment against your own chaincase before ordering.
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