Removal and disassembly
1. Jack up the rear of the vehicle and place it on jack stands. Block both front wheels with wedges.
2. Remove the rear wheel and brake drum.
3. In case of problems, screw two M8 x 1.25 mm bolts into the threaded holes in the drum and gradually tighten them, pushing the drum away from the axle shaft flange.
4. To facilitate subsequent assembly, try to remember the installation position of the components of the brake mechanism.
5. Compress the guide springs for mounting the shoes on the brake shield, turn 90°and remove the holders (spring plates), then remove the springs, spring seats and pins from the brake assembly (rear wheel drum brake components shown in accompanying illustration).
1 - finger; 2 - shoe; 3 - bracket; 4 - upper coupling spring; 5 - adjusting bar; 6 - adjusting spring; 7 - saddles; 8 - guide springs; 9 - holders; 10 - lower coupling spring
6. Disconnect from boots the bottom coupling spring and a support from brake assembly.
7. Disconnect and remove the upper return spring.
8. Spread the upper ends of the shoes to the sides, moving them away from the pistons of the wheel cylinder, then remove the shoes from the brake shield.
9. Remove the adjusting spring and expansion bar from the shoes.
10. If you are going to replace the shoes, remove the retaining ring and adjusting bracket from the inside of the shoe.
11. Disconnect the brake pipe from the wheel cylinder, give the fixing bolts and remove the cylinder from the brake shield.
12. Remove anthers, pistons, cuffs and springs from the wheel cylinder.
Cleaning and checking the condition of components
1. Assess the degree of wear of the friction linings of the brake shoes. If the lining thickness is less than the allowable (see tables of sizes and adjustments at the end of the guide), they should be replaced or new shoes installed.
2. If the residual thickness of the pads is within the normal range, inspect them for traces of oil or grease contamination, if any, replace them.
Note. Replacement pads are made in a set of four.
3. Check up brake drums on presence of cracks, scratches, scuffs and emergence of an ovality. If necessary, grind the drums or replace them.
4. Wash the wheel cylinder components with methanol, then dry them with compressed air.
5. Check pistons and cylinder bores for cavities and signs of wear. If necessary, hone the cylinder or replace defective components.
Note. On the disassembled wheel cylinder, remove the bleed valve and check its patency. Be sure to replace the rubber anthers and piston cuffs.
6. Compare the tension forces of the brake shoe return springs with those for new ones, replace the springs if necessary.
7. Make sure that the ratchet wheel rotates freely on the adjusting spreader bar. Screw it onto the bar until it stops.
Assembly and installation
Assembly is carried out in the reverse order of dismantling.
1. Lubricate the cylinder mirrors, pistons and cuffs with clean brake fluid.
2. Put the cuffs on the pistons with the sponges inside the cylinder. Track correctness of an arrangement of cuffs in flutes of pistons.
3. Dip the piston/cup assembly into clean brake fluid, then insert it into the wheel cylinder. Make sure that the lips of the cuff do not turn out during installation. Install the spring and repeat the procedure for the second piston with cup. Put anthers on the wheel cylinder on both sides.
4. Install the wheel cylinder on the brake shield. Screw and tighten with the required effort fixing bolts.
5. Make sure the brake pipe is open, then connect it to the wheel cylinder.
6. Where required, install the adjusting bracket and retaining ring on the inside of the shoe and connect the adjusting spreader bar and spring to both shoes.
7. Spread the upper ends of the shoes apart so that they do not catch on the pistons and install the shoe assembly on the brake shield.
8. Install the brake shoe pins, saddles and spring guides on the shield. Compress the springs, put on the holders (dishes) and rotate them 90°to lock the components. The components of the drum brake assembly are shown in the accompanying illustration.
9. Connect the top and bottom return springs to the shoes.
10. By turning the ratchet wheel of the adjusting expansion bar, bring the shoes together so that they enter the drum with a gap of about 0.25÷0.40 mm.
11. Bleed the hydraulic brake system, install the wheels and lower the vehicle to the ground.
12. Carry out road tests of the car, checking the serviceability of its braking.