4 Speed Gearboxes
Series 1, 2, 2a and 3 Land Rover gearboxes
The series I & II, IIA and Series III of the Land Rover gearbox remained basically unchanged from 1948 until 1970. There are 3 versions of gearboxes (transmissions) generally credited to the early Model Land Rovers.
Common and known Series I gearbox problems develop because of the low power of the 1.6 or 2l engines of the early models. In addition, the relative light weight of the vehicle itself.
The common faults include:
Second Gear damage - due to no synchromesh
Chipping of the gears
Broken main shafts
In 1958, Land Rover increased the size of the engine to try and overcome some of the early problems, however, as they used the same gearbox innards in a new housing (to fit the new engines) the problems instead of being fixed became amplified.
In 1961, Land Rover changed the gearbox specification with the introduction of the Series IIA. The Series IIA main gearbox had been strengthened to cope with larger engines and remove the earlier modification problems but also pave the way for the introduction of the 6 cylinder engine without problem.
In 1971, Land Rover opted to introduce an all new gearbox with the Series III, with the main differences being a larger clutch and the inclusion of a 4 speed synchromesh.
The Early models of the Land Rover used two types of clutch mechanism. The Series I and Series IIA used the more complicated system (some say more robust), while the Series III used a simple arm within the bell housing.
