| Also known as | 57 2166, T2166 |
| Diagram | Fig. 2 — CRANKCASE · ref 19 |
| Subsystem | gearbox |
| Listed in parts books | 1969–1974, 1976–1980, 1983, 1985 |
INSPECT/FILLER PLUG 18TPI
Slotted 18 TPI inspection/filler plug used on Triumph gearbox and primary chaincase covers.
This is the small slotted inspection/filler plug, 18 TPI, that Triumph used in a handful of spots on the gearbox and primary chaincase covers. It threads into the cover and gives you access to check or top off oil, or to get a screwdriver or wrench in for clutch cable and actuator adjustment, without pulling the whole cover off. Older parts books list this same plug as 70-0732, and you'll also see it referenced as T2166 in the legacy prefix style.
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Our catalog shows it turning up across chaincase, gearbox outer cover, gearbox inner cover, and crankcase figures, which tells you Triumph used this one plug in more than one location depending on the model and year. It's a simple threaded plug, and since it's exposed on the outside of the case, it's a common spot for someone to have lost or stripped the original over the years.
We don't have a breakdown in our records of exactly which seal (O-ring or fiber washer) goes with each application, so check what's currently fitted on your cover before you order a gasket or washer to go with it.
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