Brake mechanisms of the rear wheels are drum, with two-piston wheel cylinders with automatic adjustment of the gap between the pads and the drum

Thrust rings are inserted into the cylinder with an interference fit, limiting the free travel of the pistons (after braking), thereby maintaining a constant gap between the pads and the drum.

As the pads wear, the rings move by the amount of wear.

In the lower hole of the brake pads there are eccentrics for adjusting the position of the pads after replacing them.

The minimum allowable thickness of the rear brake pads when worn is 1 mm. The maximum permissible inner diameter of the brake drum is 283 mm.

The rear brake mechanism is shown in the figure.

Rear brake repair

Removing and installing the brake drum

Withdrawal:

  • 2. Check the position of the parking brake lever, which should be in the lowest position.
  • 3. Loosen lock nut 1 and loosen adjusting nut 2 of the equalizer, thereby loosening the parking brake cable tension on the corresponding side.

Rear brake repairRear brake repair

4. Unscrew the three mounting screws and, if necessary, remove the brake drum with a screwdriver.

Inspection:

  • 1. Clean the brake drum.
  • 2. Measure the diameter of the working surface of the drum with a caliper. The maximum allowable drum diameter is 283 mm.

If the diameter is more than acceptable, the drum must be replaced.

If there are scratches, the drum can be bored, but taking into account that after boring the diameter of its working surface is no more than acceptable.

It is recommended to replace the brake drums on both sides.

Installation:

Install the brake drum in the reverse order of removal. In this case, it is necessary to lubricate the seat on the axle shaft flange with graphite grease or Litol-24 grease.

Replacing brake pads

  • 1. Install support blocks under the front wheels.
  • 2. Loosen the rear wheel mounting bolts.
  • 3. Raise and support the rear of the car.
  • 4. Remove wheel.
  • 5. Check the position of the parking brake lever, which should be in the lowest position.

Rear brake repair

  • 6. Loosen lock nut 1 and loosen adjustment nut 2 of the equalizer, thereby loosening the parking brake cable tension on the corresponding side.
  • 7. Remove the brake drum.

Rear brake repair

8. Press the upper cup 1 of the pressure spring and, turning it by 90°, remove it together with the spring 2, while holding the pin 3 of the cup on the back of the brake shield.

Then remove the lower cup 4 of the pressure spring by turning it 90° and remove the pin 3.

Remove the spring and cups from the other pad in the same way.

Rear Brake Repair

9. Detach upper retaining spring 1 from shoes 2.

Rear Brake Repair

10. Remove the socks 2 of the shoes from the grooves of the pistons of the wheel cylinder 1.

Spread the shoes 3 and remove the spring 5 from the expansion lever 4.

Rear brake repair

11. Unscrew the nuts 1 of the support pins 2 of the blocks on the reverse side of the brake shield 3.

Rear brake repair

12. Remove the pads together with the support pins and eccentrics and disconnect the tip of the cable 1 of the parking about the brakes from the drive lever 2 rear shoes.

Rear brake repairRear Brake Repair

  • 13. Remove the eccentrics from the blocks.
  • 14. Remove the cotter pins, unscrew the fastening nuts and remove the expansion and drive levers from the blocks.

Unscrew the nut and remove the parking brake adjusting eccentric 1

  • 15. The pads are installed in the reverse order, while taking into account that the length of the friction lining of the front pad is 300 mm, and the rear pad is 250 mm.

When installing the support fingers 1, point their flats (arrows in the photo) towards each other.

Rear brake repair

Press the pistons into the wheel cylinder. If you have difficulty installing the brake drum, set the parking brake adjusting eccentric 2 so that it corresponds to the required free play of the drive lever.

After finishing work, press the brake pedal vigorously several times to set the required clearances between the pads and the working surface of the drums.

Brake cylinder

  • - Remove the brake drum.
  • - Unscrew the tube fastening nut 1 from the reverse side of the brake shield and disconnect the tube 2 from the fitting of the wheel brake cylinder.

Rear Brake Repair

Close the tube opening. Unscrew the two mounting bolts 3 and remove the wheel brake cylinder.

Disassembly

1. Use a screwdriver to pry off the protective caps 1 on both sides of the cylinder with polyurethane foam seals.

Rear Brake Slave Cylinder Disassembly

Turn the pistons 2 by 90° to either side and remove them from the cylinders. Unscrew the bleed valve 3 if necessary.

Inspection:

  • 1. Wash the parts of the wheel brake cylinder with clean brake fluid and dry.
  • 2. The mirror of the cylinder should not have scratches, shells and foci of corrosion.

If these defects are present, the cylinder must be replaced.

There must be no mechanical damage on the threaded parts of the cylinder.

  • 3. The cuffs of the wheel cylinder must be resilient and elastic.

Rorn, swollen and hardened cuffs, as well as those with marks on the working surfaces, must be replaced.

  • 4. The surfaces of the pistons in contact with the cylinder face must not show signs of wear on one side. Otherwise, it is recommended to replace the wheel cylinder assembly.
  • 5. The thread of the brake pipe tip must not be mechanically damaged.

The nozzle fitting must not have cracks or visible deformation.

Assembly:

  • 1. Lubricate the inner surface of the cylinder with new brake fluid.
  • 2. Lubricate the pistons with cups with new brake fluid and insert them into the cylinder so that the protrusions on the rear ends of the pistons fit into the grooves of the thrust rings.

Rotate the pistons 90°. Lubricate the protective rings with new brake fluid and install them in the cylinder until they stop against the pistons.

Turn the outer edges of the protective caps inside out and install them with the inner edge into the grooves on the pistons.

Fill the outer edges of the protective caps into the outer grooves on the cylinder.

Installation:

Install the brake wheel cylinder in the reverse order of removal.

Tighten the wheel cylinder mounting bolts to 8–18 Nm (0.8–1.8 kgf m).

After installation, it is necessary to bleed the repaired brake mechanism.