Rear axle bearings, side clearance and position of the contact patch in the engagement of the main pair are adjusted at the factory, and, as a rule, they do not require adjustment during operation
Their adjustment is necessary only after the bridge has been rebuilt and parts have been replaced, as well as when the bearings are heavily worn.
The side clearance in the main gear engagement, which has increased due to tooth wear, is not reduced by adjustment, as this leads to a disruption in the engagement and, as a result, to increased rear axle noise or tooth breakage.
Play in tapered bearings is eliminated without disturbing the relative position of the driven and driving gears.
Adjusting the pinion bearing preload
The need for bearing adjustment can be determined by the presence of axial play in the drive gear.
Axial play is measured with the cardan shaft disconnected using an indicator with a division value of not more than 001 mm when the flange is moved in the axial direction.
In this case, the indicator leg should rest against the end of the flange parallel to the axis of the drive gear.
Axial play in the pinion bearings must be corrected by adjusting the preload. The preload is adjusted by selecting the thickness of the adjusting ring 5.
Adjustment must be done as follows:
- — unpin and unscrew nut 1 remove flange 2, stuffing box 2 and bearing inner ring 4;
- - replace the adjusting ring 5 with a new one, the thickness of which should be less than the one being replaced by the value of the axial play plus an additional 005 mm if the vehicle mileage is less than 1000 km or 001 mm if the vehicle mileage is more than 10000 km;
- - put in place the inner ring of the bearing, a new oil seal, flange and tighten the nut to a torque of 160-200 Nm (16-20 kg / cm), then check the ease of rotation of the drive gear.
If more force is required to rotate the drive gear than it was before the adjustment, then it is necessary to replace the adjusting ring, increasing its thickness by 001-002 mm.
After adjusting the bearing preload, it is necessary to tighten the nut to a torque of 160-200 Nm (16-20 kg / cm) until the slot in the nut coincides with the hole for the cotter pin.
To match the hole for the cotter pin with the slot of the nut, it is only necessary to tighten it, because otherwise, due to insufficient tightening, the inner ring of the outer bearing may turn, wear the adjusting ring and, as a result, increase the axial play of the bearings.
When tightening the flange nut, it is necessary to turn the drive gear to properly install the rollers in the bearings.
After adjustment, it is necessary to check the heating of the bearings after driving the car at a speed of 60-70 km / h for 20-30 minutes. At the same time, the heating of the crankcase neck should not exceed 95 ° C (water that has fallen on the neck should not boil).
In case of excessive heat, the preload must be reduced.
Adjust the preload when replacing the bearings of the drive gear and final drive gear in the following order:
- - it is necessary to adjust the position of the drive gear by selecting the adjusting ring 7 of the gears and the end of the drive gear adjacent to the adjusting ring 7;
- - by selecting the adjusting ring 5, adjust the preload of the drive gear bearings.
When properly adjusted, the moment of resistance to rotation of the drive gear should be in the range of 150-200 Nm (15-10 kgf/cm) for new bearings or 70-100 Nm (7-10 kgf/cm) for used bearings.
If the moment of resistance to rotation of the bearings is within the limits, it is necessary to cotter the nut, otherwise the adjustment should be repeated.
At the same time, if the moment of resistance to rotation turned out to be less than required, it is necessary to reduce the thickness of the adjusting ring, and if more, it is necessary to choose a ring of greater thickness.
After adjusting the bearing preload, it is necessary to install the differential assembly in the axle and adjust the differential bearing preload and the backlash in the final drive gear engagement.
Adjusting differential bearing preload and backlash in the meshing of gears and final drive
Adjustment without changing bearings
To adjust the bearings you need:
- - remove axle shafts, crankcase cover and cover gasket (for one-piece rear axle);
- - remove the axle shafts and remove the gearbox from the axle housing (for a rear axle with a banjo beam);
- - with the locking plates 14 removed (see) and the covers 17 of the differential bearings loosened, use the adjusting nuts 16 to set an axial clearance of 0.01 mm in the differential bearings
- - set the indicator, and check the side clearance in the meshing of the gears, which should be within 0.15-0.25mm. Check to make at least six points, each time turning the gear;
- - to increase the lateral clearance, loosen the adjusting nut on the side of the driven gear and tighten the opposite nut by the same number of grooves. To reduce the side clearance, these operations are performed in reverse order;
- - adjust the preload value by compressing the bearings in the axial direction
By 0.1 mm with a car mileage of less than 1000 km.
On 0.05mm with a run of more than 10,000 km.
Control to carry out the angle of rotation of the adjusting nut. Turning one nut towards the other by the width of the groove corresponds to a compression of the bearings by 0.05 mm;
- - tighten the bolts of the differential bearing caps and check the lateral clearance of the gear teeth of the main gear;
- - bolt the locking plates on the bearing caps;
- - install the gearbox in the axle housing;
- - set semiaxes.
Adjustment when replacing bearings
To adjust the bearings you need:
- - remove axle shafts, crankcase cover and cover gasket (for one-piece rear axle);
- - remove the axle shafts and remove the gearbox from the crankcase (for a rear axle with a banjo-type beam);
- - remove the locking plates 14 from the covers 17 of the differential bearings;
- - unscrew the bolts of the covers, remove the covers, remove the differential and adjusting nuts 16;
- - measure the residual friction torque of the drive gear bearings with a dynamometer
- - press out the inner bearing rings from the differential box and press in new ones;
- - put the differential in place with new bearings, tightly pressing their outer rings;
- - insert adjusting nuts 16 into the threaded part of the rear axle housing, as close as possible to the bearings, and install covers 17 according to the markings on the bearing caps and on the rear axle housing;
- - fasten the bearing caps with bolts with a force that does not prevent the tightening of the adjusting nuts 16 (the holes in the crankcase for the bolts must first be lubricated with an anaerobic sealant);
- - tighten the bearings with adjusting nuts until a slight preload is obtained.
During the preload of the bearings, the driven gear must be turned a few turns in one direction, then in the other direction for the correct installation of the rollers in the bearings;
- - alternately tightening the adjusting nuts of the differential bearings, achieve an increase in the moment of resistance to rotation of the drive gear by 150-300 Nm (15-30 kgf / cm) relative to the residual moment of resistance to rotation, measured after removing the differential;
- - on the side of the driven gear and the same number of grooves, tighten the nut on the side of the drive gear to maintain the preload of the bearings, to reduce the side clearance, these operations are performed in reverse order;
- - the rotation of the adjusting nuts must be completed with a tightening.
For example, if you want to loosen a nut by one groove, then you should loosen it by two, and then tighten it by one groove. This ensures that the nut is in contact with the outer ring of the bearing and that the ring does not move during operation;
- - finally tighten the bolts of the bearing caps, fasten the locking plates on the bearing caps with bolts;
- - install gasket and rear cover (for one-piece rear axle);
- - install the gearbox in the axle housing (for the rear axle with a banjo beam);
- - set semiaxes.
Checking engagement by contact patch
After the final assembly and adjustment of the axle gearbox, the gear engagement should be checked. for this it is necessary to paint the teeth with paint.
It should be noted that very liquid paint spreads and stains the surface of the teeth, too thick - it does not squeeze out of the gaps between the teeth.
Slowing down the driven gear, rotate the drive gear in both directions until a clear contact spot is indicated.
Obtaining the correct contact pattern of the teeth completes the verification of the installation of the gears and the backlash in the mesh.
Side clearance must be within the above limits. The figures show typical contact patches on the teeth of the driven gear of the main gear of the rear axle.
Fig. 4 Correct location of the contact patch on the driven gear
The contact patch on both sides of the driven gear tooth should be located as shown in Figure 4
If during the adjustment process it becomes necessary to move the drive gear, this can be achieved by changing the thickness of the set of shims installed between the end of the gear and the end of the inner ring of the drive gear rear bearing.
Changing the side clearance changes the location of the contact patch. The contact in this case is moved like this:
- to reduce the backlash, the driven gear moves to the drive gear, the contact patch on the working (convex) side of the tooth moves slightly below and closer to the narrow end of the tooth;
- to increase the backlash, the driven gear is retracted from the drive gear:
- - on the working side of the tooth, the contact spot moves slightly higher and closer to the wide end of the tooth;
- - on the non-working side of the tooth, the contact patch moves slightly higher and closer to the wide end of the tooth;
3. When the drive gear approaches the driven gear:
- - the contact spot on the working side moves below and closer to the narrow end of the tooth;
- - the contact spot on the non-working side moves below and closer to the wide end of the tooth;
4. When moving the drive gear away from the driven gear:
- - the contact spot on the working side of the tooth moves to the top of the tooth and to its wide end;
- - on the non-working side of the tooth, the contact patch moves to the top of the tooth and slightly moves towards its narrow end.