The LT77 gearbox from the Rover SD1 has a reputation for being weak. The bearings often fail on the shafts on high powered cars. I think this may be because the 'boxes are usually secondhand and quite old when first used. I have a friend with a rebuilt LT77 in a 290HP car that has given several years service with many track days and no problems. If you want to use an LT77 it is worth trying to find a 'D' suffix gearbox as fitted to the SD1 Vitesse. This has slightly stronger internals than the earlier 'boxes and is fitted with a higher 5th gear - 0.793 instead of 0.833. The LT77 is quite particular about the oil that is used. Rover used to specify ATF to overcome baulking when cold. Some people recommend 20/50 engine oil. I have used ATF and fully synthetic 75W80, but the best oil I have used is Redline MTL. It is a fully synthetic with friction properties designed especially for gear syncros. This makes the gearchanges like a knife through butter and synchro engagement is really good.
Borg Warner T5 Gearbox
The T5 'box is rated at 350lbft of torque. It is generally acknowledged to be a stronger 'box than the LT77. To fit this you can use a bellhousing for an automatic SD1. This is shorter than the manual bellhousings and can be fitted to the T5 with an adapter plate. The easiest way to operate the clutch is to use a concentric hydraulic release bearing that is attached to the gearbox front over the input shaft.
The R380 is a development of the LT77 and is fitted to the MG V8 and the latest Land Rovers. There is a lot of conflicting advice about the installation of this 'box and whether you need to make chassis mods. I have a friend who is fitting one in the summer of '99 and will update this page with his findings. However it looks as though the bellhousing and remote from the LT77 can be attached to the R380. A small part of the chassis mounting plate for the LT77 may have to be ground away. A new prop will probably be required as the gearbox is a different length.
© Ian Crocker
Last updated on June 30th 1999