Introduction

Design and Function

Applies to: M56

The transmission and integral final drive are housed in an aluminium casing. The unique transmission design combines extremely compact dimensions with impressive torque delivery.

The gear shift movements are transmitted to the transmission by two heavy-duty cables that give a light yet smooth and precise feel to the gearshift operation. At the same time vibration and other movement from the transmission is prevented from reaching the gear shift.

The shift lever is held by rubber bushings fixed to the transmission tunnel, giving good sound insulation.

The engine and transmission rest on shock-absorbent mountings on a subframe of hot-dip galvanised steel. This subframe in turn is mounted on the body by four rubber bushings. This effectively helps prevent road noise and vibration being transmitted to the bodywork.

The transmission casing has only one mating flange, with a liquid gasket seal.

The transmission and final drive are highly compact, being just 353 mm long, and weighing 45 kg (not including oil), and with an oil capacity of 2.1 litres. The transmission oil used is of the synthetic type, and should normally never need changing.

Checking the oil level and topping the oil up is normally done via the oil level plug (A). Oil is drained via plug (B).

The shift lever bearings in the transmission casing and external actuator bearings are permanently-lubricated low-friction bearings.

The shift lever mechanism is non-adjustable. If either cable is faulty or damaged, both cables must be changed.

The LH driveshaft is connected to the final drive unit by a circlip, so that special tools are required when dismantling.