Attention! Brake pads should be replaced on BOTH rear wheels at the same time. NEVER change pads on only one wheel, as this can cause uneven braking. Be aware that the dust generated from pad wear may contain asbestos, which is hazardous to health. Never blow this dust out with compressed air or inhale it. When working on the brakes, use a respirator or cotton gauze bandage. DO NOT use gasoline or petroleum-based solvents to clean brakes. Use only brake cleaner or denatured alcohol.
1. Remove the brake drum as described in paragraph 7.
2. Remove all dust (resulting from brake wear) from the brake drum, brake shield and shoes. Take all necessary precautions so that you do not inadvertently inhale it.
3. Measure the thickness of the friction lining on each brake pad at several locations. If pad wear in any place has reached or exceeded the limit value, all four pads should be replaced. The pads must also be replaced if they are oiled, since there is no effective way to degrease a contaminated friction lining.
4. If the brake pads are unevenly worn or oily, find the cause and fix it before reassembling the brake.
5. Mark the installation position of the springs and the spacer bar with the regulator to facilitate correct assembly.
6. Unhook the end of the lower return spring from the secondary brake shoe, unhook it from the primary brake shoe and remove the spring (pic. 5.6).
Pic. 5.6. Unhook the lower return spring from the secondary brake shoe, unhook it from the primary brake choke and remove the spring
7. Using pliers, press the spring cup of the primary brake shoe support strut and turn it 90°while holding the strut on the back side of the brake shield. After removing the cup, remove the spring and then remove the post (pic. 5.7, a, b). Repeat this procedure for the strut on the secondary brake shoe.
Pic. 5.7, a. Press the spring cup, turn it 50°while holding the post on the back of the brake shield
Pic. 5.7b. After removing the cup, remove the spring, and then remove the rack
8. Disconnect the parking brake cable end from the lever on the secondary brake shoe (pic. 5.8).
Pic. 5.8. Disconnect the parking brake cable from the lever on the secondary brake shoe
9. Disconnect the governor lever spring from the primary shoe and governor lever, and then remove the governor lever (pic. 5.9, a, b).
Pic. 5.9, a. Disconnect the governor lever spring (marked with an arrow)...
Pic. 5.9b....then remove the governor lever
10. Remove the brake pads from the lower support pin and release from the pistons of the wheel brake cylinder. Spread the lower ends of the shoes apart and remove the regulator bar, the upper return spring and then the two brake shoes.
11. After removing the brake pads, fix the pistons of the wheel cylinder in the cylinder with a clamp or a strong rubber band. Do not press the brake pedal before assembling the brakes.
12. Remove the forked end of the regulator strut and carefully inspect the assembly for signs of wear or damage. Pay special attention to the threads and knurled adjuster wheel and replace if necessary.
13. Check up a condition of all coupling springs and replace the springs having signs of deformation or other damages.
14. Bend back the rubber protective caps and check the wheel cylinder for fluid leaks or other damage. Make sure both pistons can move freely. For information on replacing the wheel cylinder, if necessary, refer to paragraph 9.
15. Before installation, clean the brake shield and apply a thin layer of high temperature brake grease or other suitable lubricant to all brake shield surfaces that come into contact with the pads, in particular the wheel cylinder pistons and lower bearing. Be careful not to get grease on the friction material.
16. Verify that the parking brake lever stop pin is correctly positioned against the edge of the secondary brake shoe and that the return spring is in the correct position.
17. Connect the upper return spring to the primary and secondary brake pads (pic. 5.17).
Pic. 5.17. Connect the upper return spring to the primary and secondary brake pads
18. Use the adjuster wheel to bring the adjuster stem to its minimum length, then connect the stem to the primary brake shoe and parking brake lever (pic. 5.18).
Pic. 5.18. Attach the adjuster post to the primary brake shoe and parking brake lever
19. Turn out two bolts of fastening of the wheel cylinder to a brake board. Carefully release the cylinder from the brake shield until the bleed screw comes out of the brake shield. Move the cylinder up as far as the piping allows to get the largest possible clearance between the cylinder and the wheel hub.
20. Move the partially assembled brake pad assembly to its original position on the brake shield and insert the brake pads into the grooves on the wheel cylinder pistons (pic. 5.20).
Pic. 5.20. Install the partially assembled brake shoe assembly to the brake shield
21. Pass the lower return spring behind the lower support and connect one end to the leading brake shoe (pic. 5.21).
Pic. 5.21. Pass the lower return spring behind the support and connect one end to the primary brake shoe
22. Hold the spring on the primary brake shoe and hook the other end of the spring with a screwdriver (pic. 5.22).
Pic. 5.22. Hold the spring on the primary brake shoe and hook the other end of the spring with a screwdriver
23. Pull the spring with a screwdriver to hook it over the edge of the appropriate mounting hole in the secondary brake shoe. Now pry the end of the spring with the tip of a screwdriver and push it fully into place (pic. 5.23). Be patient as it may take several tries due to the limited space behind the secondary brake pad.
Pic. 5.23. Pull on the spring to engage it in the mounting hole, and then use the tip of a screwdriver to fully retract it into place
24. After connecting the lower spring, install the brake shoes on the lower support and at the same time insert the wheel cylinder into place. Screw in the wheel cylinder mounting bolts and tighten them securely (pic. 5.24).
Pic. 5.24. Install the brake pads on the lower support and insert the wheel cylinder into place
25. Install the adjuster lever on the primary brake shoe, making sure it is located behind the fork end of the adjuster post. Connect the governor lever spring to the lever and primary brake shoe (pic. 5.25).
Pic. 5.25. Install the adjuster lever on the primary brake shoe and connect the spring
26. Connect the end of the parking brake cable to the parking brake lever on the secondary brake shoe.
27. Insert the support column of the leading brake shoe into the brake shield and install the spring on the column. Hold the post, install the spring cup and turn it 90°. Repeat this procedure for the strut on the secondary brake pad, and then push down the pads to center their position on the brake shield.
28. Using a screwdriver, turn the adjuster strut wheel to spread the shoes just enough so that the brake drum just passes over the shoes.
29. Install the brake drum as described in paragraph 7.
30. Repeat the above procedure on the other rear brake.
31. After replacing both sets of rear pads, adjust the gap between the pads and the drum by depressing the brake pedal several times. When depressing the pedal, have an assistant listen for the sound in the rear brake drums to make sure the governor post is working properly. If everything is in order, when you press the pedal from the regulator post will come «snapping» sound.
32. Check and, if necessary, adjust the parking brake as described in paragraph 13.
33. Finally, check the brake fluid level in the brake fluid reservoir as described in «weekly checks».
34. Keep in mind that new brake pads will not provide full braking performance until then. until they work out. Be prepared for this and, after changing the pads, avoid hard braking if possible for the first few hundred kilometers.