Basic information (BMW 3 Series E46)

Torque is transmitted from the gearbox to the rear wheels via a cardan shaft, which consists of two halves. Behind the central support of the cardan shaft, there is a clutch with a sliding joint. This connection compensates for small movements of the cardan shaft back and forth. The front end of the cardan shaft is attached to the flange of the output shaft of the gearbox via a rubber coupling or cardan joint. In some models, a torsional vibration damper is installed between the coupling and the front end of the cardan shaft. The middle part of the cardan shaft is supported by an intermediate support, which is attached to the car body. At this point, as well as at the rear end of the cardan shaft, there are cardan joints to compensate for the movement of transmission elements relative to the car body and chassis.

The main transmission consists of a pinion, a driven gear, a differential, and output flanges. The pinion drives the driven gear. This wheel is sometimes called the differential input shaft. The pinion is attached to the cardan shaft using a flange joint. The differential is bolted to the driven gear of the main transmission and drives both output flanges to which the drive shafts are attached, having constant velocity joints at the ends. The differential allows the rear wheels to rotate at different angular velocities when turning.

The drive shafts transmit torque from the differential flanges to the drive wheels. Constant velocity joints are installed at each end of the drive shaft. The inner joint is bolted to the differential output flange, and the outer joint is splined to the wheel hub and secured with a large nut.

Complex repair of main gear components (pinion, wheel and differential) requires a lot of special devices, as well as high precision adjustment, so it cannot be done in a garage. If complex repair of the main transmission is required, we recommend that you contact a specialized service station.

(The original entry can be found on the portal www.bmwman.ru)