Removing the bridge from the car must be done in the following sequence:
- - loosen the rear wheel nuts;
- - disconnect the cardan shaft from the drive gear flange;
- - disconnect the parking brake cables from the equalizer;
- - disconnect the brake hose, remove the brake pipes;
- - disconnect the lower end of the brake force regulator strut from the rear axle bracket;
- - place stops under the front wheels of the car, hang out the rear axle and install it on stands to ensure a stable position of the car;
- - unscrew the wheel nuts and remove the wheels;
- - detach shock absorbers;
- - unscrew the nuts for fastening the stepladders of the springs, remove the stepladders and stabilizer brackets;
- - hang out the rear of the car using a beam crane and push the bridge out from under the car.
Dismantling the bridge
Before disassembling the rear axle, unscrew the drain plug and drain the oil.
Disassemble the bridge in the following sequence:
- - unscrew the nuts securing the axle shafts and remove the axle shafts using dismantling bolts;
- - remove the half shaft flange gaskets;
- - unscrew the outer nut of the wheel bearing, remove the lock washer, unscrew the inner nut of the wheel bearing;
- - remove the brake drum with hub assembly;
- - unscrew the bolts securing the brake to the crankcase flange and remove the brake assembly with cable and oil retainer;
- - remove the rear crankcase cover and cover gasket (for a one-piece rear axle);
- - unscrew the bolts securing the gearbox to the crankcase, remove the gearbox with dismantling bolts and unscrew the filler plug (for the rear axle with a banjo beam);
- - unscrew the breather;
- - unscrew the bolts securing the locking plates of the nuts of the differential bearings, remove the locking plates;
- - unscrew the bolts securing the differential bearing caps, remove the caps, remove the bearing nuts and the differential assembly with the driven gear;
- - unpin and unscrew the nut securing the drive gear flange, remove the flange and washer, remove the drive gear;
- - remove the inner ring of the rear bearing of the drive gear with a puller, as shown in order for the shoulders of the insert 4 to fit tightly between the bearing race and the gear, the supports 2 should be compressed with bolts and nuts 3.
Press out the bearing inner race by turning screw 1;
- - remove adjusting ring;
- - press out the outer races of the drive gear bearings.
The differential must be disassembled in the following order:
- - unscrew the bolts of the driven gear, remove the driven gear;
- - press the inner races of the differential bearings with a puller assembly with liners, as shown in the picture
In order for the shoulders of the liners 1 to fit into the recesses on the differential box, the supports 2 should be compressed with bolts and nuts 3; press the bearing ring by turning screw 5.
Inspection and control of bridge details
Place the parts of the disassembled rear axle (excluding bearings) in a cleaning solution, then rinse and inspect carefully.
Replace parts with cracks. If there are nicks, burrs and other irregularities on the machined surfaces of the parts, clean them to ensure a good fit of the mating parts.
In this case, special attention should be paid to the condition of the seating surfaces for bearings.
Check the bearing rings for scoring or uneven wear.
Check the condition of the ends of the rollers.
Stepped wear on the ends of the rollers indicates insufficient preload of the bearings or misalignment of the rollers.
Inspect the drive and driven gear teeth for nicks or excessive wear.
Worn gears and gears with scuffs are unsuitable for further work.
Temporarily install the differential bearing caps and check that the nuts are screwed in.
The nuts should turn freely.
The ends of the nuts in contact with the bearings must be perpendicular to the axis of the thread. The runout of these ends relative to the axis of the thread should be no more than 0.02 mm.
The surface of the ends must be clean and smooth, must not have stepped wear.
Make sure the bearing caps are installed on the side they were machined on.
The end face of the pinion flange in contact with the bearing must be smooth, if necessary, it should be ground.
The second end of the flange in contact with the washer must also be smooth, roughness and nicks on the ends of the flange weaken the bearings.
The neck of the flange should not have nicks, scratches, heavy wear in the cuff operation area, there should be no sharp edges on the lead-in chamfer.
The axle housing must not be damaged or permanently deformed.
The surfaces of the bearing housings must be smooth, the threads for the nuts of the differential bearings must not be damaged.
It is necessary to remove all bumps and burrs from the seating surfaces of the gearbox housing. Clean the oil channels.
Inspect the teeth and bearing surfaces of the gears of the axle shafts and satellites, the bearing and seating surfaces of the satellite boxes. They should be smooth, free of nicks or nicks, and free of uneven wear or metal encrustation.
Worn side gear journal can cause increased rear axle noise.
Worn bearing surfaces or thrust washers cause an increase in backlash in the engagement of the differential gears and a violation of the correct engagement of the gears.
Check the fit of the inner rings of the differential bearings to the bearing surfaces of the differential pinion boxes - a 0.03 mm feeler should not pass between the ring and the end of the box.
The inner rings must not rotate freely on the necks of the boxes.
Pay particular attention to ensure that the mating surfaces of both differential pinion boxes and the surface of the driven gear mounting flange are smooth and free of burrs.
It is necessary to check the runout of the head of the driven gear, as shown in - for a one-piece rear axle (for a rear axle with a banjo beam - similarly, with the gearbox removed) allowable runout is 0.08 mm.
If during inspection it turns out that the runout exceeds the specified value, then it can be assumed that deformation of the driven gear, damage to the differential boxes, or excessive bearing wear.
Unsuitable parts are repaired or replaced.
The axle housing should not have significant wear in the area of operation of the hub cuff, the surface under the cuff should be smooth, without scratches and nicks.
Before assembly, all friction surfaces of the differential parts must be lubricated with the oil used in the axle.
Assemble the differential in the following order:
- - install the side gear washer and the side gear in one of the satellite boxes;
- - install satellites and support washers of satellites on the axis of the satellites;
- - install the axis of the satellites with satellites and washers in the box of satellites with the groove up;
- - assemble the second satellite axis as above;
- - install the second axis of the satellites with the groove down and install the second side gear and washer from above;
- - place the second box of satellites so that the marks on the right and left boxes are opposite each other;
- - wrap and tighten the bolts of the satellite boxes with a torque of 28-36 Nm (28-3.6 kgcm), having previously applied the Unigerm-6, Unigerm-9 or Stopor-b anazobic sealant to the threads of the holes for the bolts ”, 0.1 g per hole.
The threads in the holes of the box and on the bolts must be dry and degreased before applying the sealant;
- - press the driven gear onto the left satellite box and fasten it with bolts. Bolt tightening torque 68-75 Nm (6.8-7.5 kgcm).
Before tightening the bolts, apply the specified sealant to the threads of the bolt holes in the gear, 0.2 g in each hole, having previously degreased and dried the threads on the bolts and in the gear;
- - check the ease of rotation of the differential gears by rotating one of the axle gears with the help of a splined mandrel with the differential housing stationary.
The rotation should be smooth, without jamming. The torque required to rotate the differential gears must not exceed 15 Nm (1.5 kgcm).
When assembling the rear axle with new drive gear bearings or final drive gears, the drive gear bearing preload and position must first be adjusted (see Rear Axle Adjustment).
Assemble the bridge in the following order:
- - install the adjusting ring 7 of the drive gear on the drive gear and press the inner ring of the rear bearing to the stop;
- - press the outer rings of the drive gear bearings into the crankcase;
- - install the drive gear in the outer ring of the rear bearing;
- - put adjusting ring 5 bearings 6;
- - install the inner ring of the front bearing of the drive gear;
- - press the cuff 3 of the drive gear flush with the end of the crankcase;
- - install flange 2, washer, tighten and cotter nut 1 of the flange (see Adjusting the final drive);
- - install the differential with bearings in the crankcase, tightly pressing their outer rings;
- - install the adjusting nuts of 16 differential bearings into the threaded hole of the crankcase as close as possible to the bearings and install the covers of 17 differential bearings;
- - tighten the bolts for fastening the covers with a torque that does not prevent the rotation of the adjusting nuts of the differential bearings. Before tightening the bolts, apply Unigerm-6 or Unigerm-9 anaerobic sealant to the threads of the holes in the axle housing.
The threads in the crankcase and on the bolts must be cleaned, degreased and dried;
- - adjust the differential bearing preload and the position of the driven gear (see Adjusting the differential bearing preload and side clearance in the final drive gear engagement);
- - finally tighten the bolts of the differential bearing caps with a torque of 90-110 Nm (9-11 kgcm);
- - bolt the locking plates of 14 differential bearing nuts;
- - apply the Un-25 sealing paste on the gasket 13 on both sides, after exposure, install the gasket on the end of the crankcase;
- - install the gearbox in the axle housing and tighten the bolts of its fastening to a torque of 55-70 Nm (5.5-7.0 kgf m);
- - install brake assembly and oil deflectors. The tightening torque of the oil deflector bolts is 14–18 Nm (1.4–1.8 kgcm), the brake mounting bolts are 50–62 Nm (5.0–6.2 kgcm);
- - install the right and left hubs with brake drums as an assembly and adjust them;
- - install half shaft spacers on the hub studs;
- - insert the axle shafts and tighten the nuts of the axle shafts to a torque of 90-125 Nm (9.0-12.5 kgcm);
- - install and lock with locknuts the bolts for dismantling the axle shafts;
- - install a drain plug in the crankcase and screw in the breather;
- - fill the bridge with oil according to the lubrication map through the filler hole in the cap and tighten the filler plug; fill the hubs with the same oil by alternately tilting each side of the axle to a height of at least 200 mm;
- - check the noise level, heating and make sure there are no oil leaks in forward and reverse gear at a drive gear speed of 16, 25, 50 s—1
Check the operation of the differential at a speed of 25 s—1 (1500 min1), braking each of the axle shafts in turn.
The total time for checking and running in the bridge is about 5 minutes. The check should be carried out with oil heated to a temperature of 45-75 ° C and an excess pressure inside the bridge of 20-30 kPa (02-0.3 kgf / cm2).
When assembling the rear axle, the dimensions of the mating parts of the rear axle should be taken into account.
Installing the bridge
The installation of the bridge on the car must be done in the following order:
- - hang out the rear of the car using a beam crane, start the bridge mounted on the stand under the car, lower the car onto the bridge so that the coupling bolts of the springs enter the holes in the spring cushions;
- - install ladders, stabilizer brackets, shock absorbers, tighten the nuts for fastening the ladders;
- - install the wheels and tighten the wheel nuts;
- - raise the car, remove the supports from under the bridge;
- - install the brake pipes, connect the brake hose and the lower end of the brake force regulator strut;
- - attach the parking brake cables to the equalizer;
- - attach the cardan shaft to the drive gear flange;
- -finally tighten the wheel nuts;
- - bleed the brake system.