10.1. General information

General information

The present Chapter is devoted to the description of the components serving for transfer of rotation from the transmission to driving wheels of the car. The driveshaft, assembly of the main transfer and power shafts of the back bridge are among such components.


Engine capacity is transferred from transmission to the back bridge by means of the two-section driveshaft connected behind the central bearing by the so-called "the sliding coupling", the shlitsevy sliding connection. The sliding coupling allows easy longitudinal movements of the driveshaft. The forward end of the driveshaft fastens to a transmission flange by means of the elastic rubber coupling.

This coupling which is called sometimes by "Guibo", or "a flexible disk" protects the driveshaft and differential from breakthroughs at rotation of the engine. On some models between an output flange of transmission and the elastic coupling establish a vibration quencher. The middle of the driveshaft is supported by the central bearing installed on a rubber pillow for mitigation of vibration of a shaft.

The casing of the bearing is attached by bolts to a car body. The forward end of the driveshaft is combined with transmission by means of the centering guide turned in cardan to a shaft; the centering guide connects to the centering finger on a transmission flange. Cardan hinges are located at the central bearing and at the back end of the driveshaft to compensate movements of transmission and differential on their support, and also any deflections of the chassis.

Assembly of differential / main transfer

The assembly of differential located in a back part of the car includes the leading gear wheel, a gear wreath (the conducted gear wheel), differential and output flanges. The leading gear wheel which rotates a gear wreath is called sometimes also entrance shaft of differential. It is connected to the driveshaft by means of a flange. The differential fastens bolts to the conducted gear wheel and rotates back wheels through couple of output flanges attached to power shafts by the hinges of equal angular speeds (HEAS). The differential allows wheels to rotate with different speeds during commission of turns (the external wheel has to move a little quicker than turn, internal in view of a difference of radiuses). Assembly of differential fastens bolts to bearing the back bridge and by means of elastic rubber plugs to a body.

Serious repair of components of assembly of differential (the leading gear wheel, a gear wreath and differential) demands a set of special tools and devices, and also considerable experience and therefore it is the best of all to provide it to specialists of dealer office of the BMW service or auto repair shop.

Power shafts and CV JOINTS

Power shafts transfer rotation from output flanges of differential to back wheels of the car. Power shafts are equipped since both ends with the hinges of equal angular speeds (HEAS).

The CV JOINT function generally coincides with function of the standard cardan hinge, but the CV JOINT can compensate big corners of a deviation of power shafts, than the cardan hinge. CV JOINTS allow power shafts to transfer rotation to back wheels, moving together with a back suspension bracket, even when assembly of differential up and down, power shafts and wheels are not balanced.

Internal CV JOINTS on all models fasten bolts to differential flanges. External hinges are identical to internal. Each hinge is filled by special lubricant and closed by a rubber protective cover. Regularly check a condition of protective covers. Damage of a cover leads to pollution of the hinge.

Hinges on the cars described in this manual are not subject to repair, but they can be removed and cleaned during replacement of protective covers. Both internal, and external CV JOINTS on all models are subject to replacement in an individual order.