| Also known as | D3500 |
| Diagram | Fig. 11 — GEARBOX SHAFTS AND GEARS · ref 6 |
| Subsystem | gearbox |
| Listed in parts books | 1971–1974, 1976–1980, 1983, 1985 |
Oil seal, high gear
Oil seal for the mainshaft high gear in the Triumph 5-speed gearbox, PN 60-3500 (D3500), supersedes 60-3500T.
This is the oil seal for the high gear (mainshaft) on the Triumph 5-speed gearbox. It sits in the gearbox shell around the mainshaft where the high gear assembly lives, keeping gearbox oil from working its way out past the shaft. The catalog lists it as PN 60-3500, also stamped D3500 on older stock, and it supersedes the earlier 60-3500T.
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You'll find it called out across the shaft-and-gear figures for the 5-speed box, including the dedicated 5-speed parts listings for the T150V triple. It's a small, easy-to-overlook seal, but a tired one will let oil seep out around the mainshaft and make a mess of your gearbox area over time.
Given how many gearbox figures this part shows up in, it's clearly a long-running fitment across the 5-speed catalog. If you're rebuilding the high gear end of the box, this is the seal to pull and replace while you're in there.
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