External gearbox components are those serviceable from outside the gearbox casing, the gear lever and its housing, the selector linkage, oil seals, gaskets, and mountings. Many of these can be renewed without removing or splitting the gearbox, making them among the most commonly replaced gearbox parts. Two entirely different gearboxes were fitted to the Midget, so the correct type must be identified before ordering.
A-Series Remote and Gear Lever
The BMC A-Series gearbox fitted to the 1098cc and 1275cc cars carries a remote selector housing on the rear extension, which holds the gear lever and the anti-rattle components. The anti-rattle mechanism, bushes, plungers, springs, and a button, sometimes called a "zizzle kit", damps the fine rattle common at cruising speed.
These parts wear and are renewed from within the passenger compartment through the remote housing, without removing the gearbox.
1500cc Single-Rail Selector
The Triumph single-rail gearbox fitted to the 1500 uses a different gear lever and selector arrangement, with the lever mounted on the rear extension and a single selector rail internally. No external selector or lever components are shared between the A-Series and single-rail gearboxes, so the gearbox type must be confirmed before ordering any external part.
Gaiters, Seals and Gaskets
The gear lever passes through rubber gaiters that seal the transmission tunnel against draughts, fumes, and noise; these perish and are a common renewal. The gearbox front cover and rear extension oil seals prevent oil loss at the input and output, and the casing gaskets seal the cover, side plate, and extension. A leaking front or rear seal is a frequent cause of oil contamination of the clutch or a tunnel oil leak.
Mountings and Ordering Considerations
The gearbox is supported at the rear by a mounting that isolates vibration; a collapsed mounting causes harshness and driveline noise. Identify the gearbox type (A-Series or single-rail) before ordering, as remote housings, levers, seals, gaskets, and mountings differ between the two. Renewing perished gaiters and worn anti-rattle parts together restores a tight, quiet gear change.