| Also known as | T4039 |
| Diagram | Fig. 8 — GEARBOX SHAFTS, BEARINGS AND INNER COVER · ref 11 |
| Subsystem | gearbox |
| Listed in parts books | 1970, 1974 |
MAINSHAFT c/w THIRD AND LOW GEARS
Gearbox mainshaft complete with third and low gears, Triumph part 57-4039 (formerly 57-2275).
This is the gearbox mainshaft, sold complete with third and low gears already fitted, from the gearbox shafts, bearings and inner cover figure. It's a rotating internal component of the transmission, carrying the third and low gear pairs on the shaft itself, so you're not buying a bare shaft and hunting down gears separately.
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The part number 57-4039 shows up in the catalog under the older number 57-2275 as well, so if your parts book or a takeoff part is stamped with that earlier number, it's the same physical piece. It also carries the legacy T4039 form for anyone working from an older reference.
Catalog listings for this part span 1970 through 1974. If you're rebuilding a gearbox and pulling the old shaft, check the tooth count and gear arrangement against what's currently in the case before ordering, and call the shop if you're not sure your box matches this version.
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