Land Rover Series 3 LT76
The Land Rover Series III gearbox has syncro in all gears as well as lower first and reverse gear ratios. The transfer case remained the same as was used on the late IIA. Series IIA gearboxes (D suffix & later) are generally considered to be stronger and longer lasting than early series III gearboxes (The ones imported into North America). Though a lot of this conception may have to do with people’s shifting habits. Series III boxes prefer that you hesitate briefly in the neutral position while you shift gears. This puts less stress on the syncros and enhances their service life. Suffix letters on the Series III gearboxes restarted with suffix A.
There were changes made to the SIII gearbox during its 14 years of manufacture, mostly to make them less prone to wear and to keep them from jumping out of gear. The suffix D and later Series III gearboxes (manufactured after Land Rover left the US) are considered to be the most robust of the Series Land Rover gearboxes. The principal changes were to the reverse idler gear, bearing and shaft and the syncro units.
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Defender/Discovery/RRC LT77
When Rover (still part of British Leyland) decided to go to a five speed gearbox they picked the existing LT77 for use in certain vehicles. The LT77 is an updated version of an old Jaguar gearbox that found its way into current model British cars manufactured by British Leyland. Yes the distance between the main and lay shafts is 77 mm. There were two version of this gearbox. The earlier version is known as the short stick version. The later version, introduced around 1988 is known as the long stick version.
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The Range Rover received the LT77 in 1984 because it was less expensive than the new LT85 and considered strong enough for the 3.5L V8 to use as a street cruising gearbox. The four cylinder Ninety and One Ten also received the LT77. When the Discovery was introduced it got the LT77 as well.
The LT77S was introduced to the Defender V8 line and all models using the Tdi engine as an interim replacement for the no longer available LT85. The LT77S was a strengthened version of the LT77. The ‘S’ on the LT77S stands for ‘Synchromesh’…it was modified for a ‘smoother gear change’. The bell housings and input shafts of the LT77S differ between the V8 and Tdi due to Tdi’s more aft location.
Defender/Discovery/RRC R380
The R380 box was introduced as brand new LR gearbox across the entire Land Rover and Range Rover product lines. The R380 is a radically reworked LT77 (The 1940’s Jag gearbox remember) with improved main shaft bearing arrangements that provided an overall strengthening of the box. The R380 name stands for “Rated to 380 Nm input”. But the R380 still has the LT77’s 77 mm shaft spacing. Since Rover was no longer part of British Leyland the LT prefix was abandoned.
The V8 and Tdi R380 gearboxes have different bell housings and primary input shafts.
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Defender/Discovery/RRC LT230 Transfer Box
The Transfer Box is a device specific to 4×4 vehicles. It is essentially an extra Gearbox attached to the back of the main Gearbox that controls the selection of High and Low ratios. This doubles the number of gears available to the vehicle whilst simplifying their selection.
On a Land Rover, the Transfer Box is also responsible for locking the central differential between the front and rear propshafts. Specifically, the Transfer Box transfers power to the front propshaft, which is also connected to the differential, which sends on power to the rear propshaft. When the differential is locked, it is effectively removed and power to both axles is constant.
The Transfer Box also takes the speed measurement for the Speedometer from a worm gear on the outside of the housing.
Land Rovers have been known to have solid Transfer Boxes through the years, and so haven’t been updated in their design that often.
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Defender Stumpy R380
The Stumpy R380 box was introduced as a replacement for the 200tdi Defender LT77 that failed during the warranty period. Land rover stopped using the LT77 and to cover failures they modified the standard 300tdi R380 to fit in where the LT77 did on earlier models. This meant fitting a custom input shaft, bell housing, clutch release bearing and front cover for the Stumpy R380.
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