| Also known as | T1112 |
| Diagram | Fig. 2 — CRANKCASE · ref 34 |
| Subsystem | engine bottom |
| Listed in parts books | 1963–1968 |
Drain plug (with level tube)
Gearbox drain plug with built-in oil level tube for the Triumph unit-construction transmission, PN 57-1112.
This is the drain plug with attached level tube that Triumph fitted to the unit-construction gearbox, part number 57-1112, also found in older parts books under T1112. It sits low on the gearbox casing and does two jobs at once — it lets you drain the transmission oil and, thanks to the tube brazed or fitted into it, sets the correct oil level so you don't overfill the box.
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It shows up in the crankcase-area figures across catalog entries running 1963 to 1968, so it's a long-running fitment across that stretch of the unit twin lineup. Plated finish is standard on these. When you pull it, it's worth having a fresh sealing washer on hand rather than reusing the old one, since a tired washer is the usual cause of a gearbox that seeps at this spot.
Check the tube length and thread against what's coming out of your gearbox before ordering, since level plugs like this are easy to mix up with a plain drain plug that has no tube at all.
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