External gearbox components for the 1500cc Triumph single-rail gearbox include the front cover assembly, rear extension housing, speedo pinion, reversing light switch, gear lever components, and the gasket set. The most critical distinction on the 1500 gearbox is the front cover type.
1500cc Identification
Two front cover types were produced: the oil seal type (gearbox numbers up to 59162, and 60001 to 65224) uses a conventional lip seal, while the oil thrower type (59163 to 60000, and 65225 onward) uses a rotating disc that flings oil away from the joint. The two covers and their respective sealing components are not interchangeable, fitting the wrong type will result in an oil leak from the front of the gearbox that no amount of gasket sealant will cure. The gearbox serial number must be checked before ordering.
Gear Lever
The gear lever on the 1500 is a different design from the 1275cc, with its own unique grommet, gaiter, and retainer plate. The gearlever retainer changed from June 1978 onward.
When replacing the gear lever gaiter, the grommet that seals the lever aperture in the transmission tunnel should be renewed at the same time, a perished grommet allows exhaust fumes and road noise into the cabin.