The main gear drive gear is made integral with the shaft (shank) and is installed in the neck of the gearbox on two tapered bearings.

The outer rings of the bearings are pressed into the throat seats, and the inner ones are put on the shank

A spacer sleeve is installed between the inner rings; when the shank nut is tightened, the sleeve deforms, maintaining a constant preload on the bearings.

The preload of the bearings is controlled by the torque of the drive gear (other parts are not installed).

For new bearings, the turning moment should be in the range of 157-197 Ncm, for bearings after a run of 30 km or more - 39-59 Ncm.

In this case, the shank nut is tightened with a torque of 118-255 Nm, periodically checking the rotation of the drive gear.

Особенности конструкции заднего редуктора ВАЗ-2123

If the specified torque has already been reached and the tightening torque of the nut is less than 118 Nm, it is necessary to replace the spacer sleeve with a new one, as the old one is too deformed.

Replacing the bushing is also necessary when the turning torque is higher than the allowable one (due to inattention when tightening).

If the main pair or the bearings of the pinion gear are replaced, it is necessary to re-select the thickness of the adjusting ring. It is mounted on the shaft between the pinion gear and the inner ring of the large bearing.

The final drive pinion is attached to the differential box flange with special bolts without washers. These bolts must not be replaced with any other bolts.

The differential box rotates in two tapered bearings. Their preload, as well as the clearance between the teeth of the main drive gears, is regulated by nuts wrapped in split bearing beds.

Half-axle gears are installed in cylindrical seats of the differential box and rest on it through support washers.

These washers are selected in thickness so that the gap between the teeth of the satellites and half-axle gears is in the range of 0.0-0.1 mm.

The satellites are mounted on an axle with constant meshing with half-axle gears. On the axis there are spiral grooves for supplying lubricant to the rubbing surfaces.

The axle shaft at one end rests on a single-row ball bearing (with shields and a lifetime lubricant supply) installed in the rear axle beam seat, and at the other (splined) end it enters the half-axle gear.

The inner ring of the bearing is secured to the axle shaft by a snap ring fitted with an interference fit (shrink fit).

The outer ring of the bearing is fixed by a plate, which, together with an oil deflector and a brake shield, is attached by four bolts and nuts to the rear axle beam.

Determination of gearbox malfunctions by noise

Perform troubleshooting in the following order.

Особенности конструкции заднего редуктора ВАЗ-2123

Challenge 1

To clearly identify the nature of the noise, drive on the highway at a speed of approximately 20 km / h.

Then gradually increase your speed to 90 km / h while listening to the different types of noise at the same time and noticing the speed at which they appear and disappear.

Release the throttle pedal and release the engine speed without braking.

Watch for the change in noise as you decelerate, as well as for the moment when the noise increases.

Usually, noise comes and goes at the same speeds, both during acceleration and deceleration.

Challenge 2

Accelerate the car to approximately 100 km / h, put the gear lever in neutral and let the car roll freely until it stops; watch for the nature of the noise at different deceleration rates.

The noise, depending on the manipulation of the accelerator pedal, comes from the main pair.

Bearings, on the other hand, can make noise in the run-up: the bearings of the drive gear make a hiss and rumble, and the bearings of the differential and axle shafts produce a low-frequency rumble.

Challenge 3

With the car stationary and braked, turn on the engine and, gradually increasing its revs, compare the noises that have arisen with those seen in the previous tests.

Noises that appear similar to those from Test 1 will indicate that they are not gearbox noise and are caused by other components.