| Also known as | E4152 |
| Diagram | Fig. 15 — CHAINCASE AND CHAINS · ref 7 |
| Subsystem | primary |
| Listed in parts books | 1964–1971, 1974, 1976–1979, 1985 |
TIE ROD,PRIMARY CHAIN TENSIONER
The primary chain tensioner tie rod for Triumph unit twins, part number 70-4152, used to adjust primary chain tension inside the chaincase.
This is the tie rod for the primary chain tensioner, part number 70-4152, also listed under the older E4152 designation. It shows up in the parts books under chaincase and gearbox cover figures, which tells you it lives inside the primary chaincase where it connects to the tensioner blade that rides against the primary chain.
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The rod is what you turn to move the tensioner blade and take slack out of the primary chain as it wears in over time. It's a simple mechanical link, but if it's bent, seized, or missing, you lose the ability to adjust chain tension properly, which leads to noise and premature chain and sprocket wear.
This one shows up across a long run of unit-construction Triumph twin catalog entries, so it's a part worth keeping in mind whenever you're in the chaincase for a clutch job or a chain change. Check the old one for straightness and freedom of movement before you decide whether to reuse it.
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