A five speed conversion kit replaces the factory four-synchromesh gearbox with overdrive with a single five-speed manual gearbox. The conversion provides closer ratios across the gearset and places the fifth-gear ratio under direct shifter control rather than requiring the column-stalk overdrive switch. Five-speed conversions are a popular upgrade for V8 owners seeking a more modern transmission feel and the convenience of a single shifter.
Kit Contents
A complete kit includes the five-speed gearbox itself, an adaptor bellhousing that mates the gearbox front face to the Rover V8 engine, gearbox mounting hardware appropriate to the new gearbox dimensions, a propshaft of revised length to suit the new gearbox tail position, and the speedometer drive components needed to retain accurate speed and odometer readings. Some kits also include a clutch release mechanism appropriate to the new gearbox specification.
Installation Considerations
The conversion is a substantial mechanical undertaking. The original gearbox crossmember position may require modification to suit the new gearbox dimensions. The propshaft must be checked for correct length and balance after installation. The speedometer must be calibrated to the new gearbox output, different five-speed gearboxes have different speedometer drive ratios, and matching the dashboard gauge to the gearbox output is essential for accurate reading.
Specification Discussion
The appropriate specification depends on the rest of the car's drivetrain. Cars with capacity-upgrade engines benefit from gearbox internals matched to the higher torque output. Cars retaining the standard 3528cc engine work well with standard-specification five-speed conversions. Engineering staff are available to discuss the appropriate kit specification before order.
MGOC Spares
MGOC Spares supplies five speed gearbox conversion kits for the MGB GT V8, with engineering staff available to advise on specification, installation requirements and matching to the rest of the drivetrain.