The taper roller bearings of the drive bevel gear shaft are adjusted with a slight preload; axial play is not allowed

The torque required to rotate the shaft in the bearings should be in the range of 0.08-0.16 kgm, which corresponds to a force of 1.3-2.7 kg applied to the flange hole 21 (for the middle axle gearbox - to hole of the smaller flange 29).

The moment can be checked using a steelyard (dynamometer).

It is necessary to measure the torque when the flange is smoothly turned in one direction and after at least five complete revolutions of the shaft.

The bearings must be lubricated with the grease specified in the lubrication chart.

When checking the torque of the drive gear of the front and middle axles, the bearing cover 28 must be shifted so that the centering ledge of the bearing cup 25 comes out of the cover seat and the oil seal does not resist the rotation of the gear, and the nut of the drive gear flange must be tightened.

The tightening torque of the nut should be 20-25 kgm.

When tightening the nut, it is necessary to rotate the drive gear shaft so that the bearing rollers take the correct position between the conical surfaces of the rings.

The drive gear bearings should be adjusted by selecting shims 32 of the required thickness, installed in the amount of 2 pcs. between the ends of the inner bearing rings.

Adjusting washers are produced at the factory in the following thicknesses: 7.25; 7.30; 7.40; 7.50; 7.60; 7.70; 7.80 and 7.85 mm.

After final adjustment of the bearings, the pinion flange mounting nut must be tightened and cottered.

Double-row tapered roller bearing 12 of the drive spur gear shaft 8 is supplied by the manufacturer with a matched adjusting ring 13 and does not require additional adjustment, the parts of this bearing are not interchangeable, therefore, rearranging parts from one bearing to another and rearranging the inner rings of the bearing one in place of the other are not allowed.

The inner ring of the bearing 12, which has a stamp on the end - the letter V, must be installed from the side of the stamped end of the outer ring.

After tightening the bearing fastening nut 12, it must be locked by pressing its thin edge into one of the shaft grooves.

The tightening torque should be 35-40 kgm. If it is necessary to unscrew the nut during repair, it must first be unlocked by bending the thin edge of the nut, crimped into the groove of the threaded end of the shaft.

The driving 23 and driven 5 bevel gears of the gearbox are selected at the factory into sets according to the contact patch and side clearance in engagement, lapped and branded with the serial number of the set.

In addition, during the operation of the car, the gears run in one to the other, so if a gear needs to be replaced, both gears should be replaced at the same time.

Newly installed bevel gears must have the same set serial number.

When installing new bevel gears of the reducer, they must be adjusted according to the contact patch, “on the paint” and according to the side clearance in engagement (Table 1 at the end of the article)

The contact patch on both sides of the driven bevel gear tooth should be approximately ⅔ of the tooth length and should not extend 2-4 mm to the end of the narrow end of the tooth, and should not extend to the top edge of the tooth.

On the drive gear, the contact patch can reach the top edge of the tooth.

The contact patch is obtained by rotating the drive gear in both directions while simultaneously braking the driven gear by hand.

Side clearance must beb within 0.15–0.40 mm at the widest part of the tooth, which corresponds to the rotation of the flange 21 of the drive bevel gear shaft by 0.18–0.48 mm when measured at the radius of the bolt holes and with the driven gear stationary, for of the middle axle gearbox, the measurement is made on the smaller flange 29.

The backlash must be checked for at least four teeth of the driven gear, spaced at approximately equal distances around the circumference.

When installing new gears in the gearbox, it is necessary to install shims 24 with a total thickness of 2 mm under the cup flange 25 of the drive gear bearings; after that, adjust the side clearance by moving the driven bevel gear by changing the number of shims 10 under the flange of the seat 9 of the driven bevel gear bearings, and check the contact patch.

If at the same time the correct contact patch did not work out, it is necessary to move the bevel gears, as indicated in Table. 1 by changing the number of shims under the flanges of the drive gear bearing cup and the driven gear bearing housing.

After final adjustment, each set of shims must have at least two 0.1 mm thick shims.

Thin shims should be placed on both sides of the shim set to achieve a tight, leak-free seal.

The bolts for fastening the cup, seat and bearing caps must be tightened after final adjustment; tightening torque 6-8 kgm.

After the shaft 25 (Fig. 4) assembled with the bearing cup is installed in the crankcase of the gearbox of the front drive axle, it is necessary to release the bearing rollers from pressing the ends against the bearing rings with a light blow through the mandrel on the end face of the outer ring of the cylindrical roller bearing 29 from the inside.

Cover 28 of the gearbox housing must be removed.

If the gears have an increased circumferential clearance in engagement due to tooth wear, then they should not be adjusted, as this violates the correct engagement.

The bevel gears should run until worn out without further adjustment.

If the increase in circumferential clearance is due to wear of the tapered roller bearings, i.e. if there is a noticeable axial clearance in the bearings at the same time as the side clearance increases, the side clearance can be reduced by removing an appropriate number of shims to compensate for this wear; in this case, it is first necessary to restore the preload of the bearings of the drive bevel gear.

After adjustment, be sure to check the correctness of the contact patch.

The assembled differential should be installed in the gearbox housing after installing and adjusting the bevel gears and final tightening of the bearing cap bolts.

After installing the differential assembly with bearings in the housing of the gearbox housing, tighten the adjusting nuts 2 (see Fig. 3) of the bearings by hand so that they fit snugly against the bearing rings, and then put the differential bearing caps on.

If the caps do not fit properly, the adjusting nuts are misaligned and need to be tightened again.

Forcing caps on can damage the crankcase, caps, and nuts.

After installing the bearing caps, tighten the nuts securing the caps to the stop and then loosen them so that you can turn the adjusting nuts 2.

When tightening and unscrewing the adjusting nuts, it is necessary to shift the differential so that the driven cylindrical gear 14 takes a position symmetrical with respect to the drive gear 8.

The differential tapered roller bearings should be adjusted with a slight preload.

To do this, first adjust the adjusting nuts so that the differential has an axial movement not exceeding 0.1 mm.

It is necessary to check the amount of axial movement with an indicator installed against the crown of the driven spur gear and fixed on the bearing cover.

After that, each of the adjusting nuts must be screwed into one groove, locked in this position with stopper 1, screw the nuts for fastening the bearing caps and cotter them (the tightening torque should be 17-19 kgm).

When adjusting the bearings, it is necessary to rotate the differential several times so that the bearing rollers take the correct position between the tapered surfaces of the rings.

When assembling the differential, it is necessary to ensure that the marks on the cups 20 are set one against the other, the tightening torque of the differential bolt nut must be 12-14 kgm.

Adjusting the bearings and gears of the front drive axle gearbox is similar to adjusting the rear and middle axle gearboxes.

It must be remembered that when the car moves forward, the working side of the driven bevel gear tooth is the convex side for the rear and middle axles, and the concave side of the tooth for the front axle.



spots on slave


Ways to get it right

gear mesh




Position of the contact patch on the driven gear



Position of the contact patch on the driven gear

Correct contact

Position of the contact patch on the driven gear

Move the driven gear to the drive gear.

If this is too small

tooth side clearance,

move pinion away

Gear movement direction
Position of the contact patch on the driven gear

Move the driven gear away from the drive gear.

If this makes it too big

tooth side clearance,

move pinion

Gear movement direction
Position of the contact patch on the driven gear

Move the drive gear to the driven gear.

If the side clearance is too small,

move driven gear

Gear movement direction
Position of the contact patch on the driven gear

Move the drive gear away from the driven gear.

If the side clearance is too large,

move driven gear

Gear movement direction