Attention! Remember that the brake shoes must be replaced only as a set and simultaneously on both wheels of the axle - replacing the pads of only one of the brake mechanisms leads to a violation of the uniformity of the gripping force and loss of vehicle directional stability during braking.
Do not forget that the dust generated during the wear of the friction material of the pads may contain asbestos, which is harmful to health - in no case blow it off with compressed air or inhale it. When servicing brake mechanisms, wear a protective mask or respirator. Do not use petroleum-based solvents to remove brake dust - wipe brake components only with methanol or a special cleaner.
1. Remove the brake drum (see Section Removal, check of a condition and installation of drums of brake mechanisms of back wheels).
2. Slowly and observing all necessary precautions, clean the drum, shield and brake shoes from brake dust.
3. At several points, measure the residual thickness of the friction linings of the shoes. If at least one of the shoes is worn below the permissible limit, they should be replaced as a set (on both wheels). The shoes must also be replaced if they show traces of oil, grease or brake fluid.
4. If there are signs of uneven wear on the friction linings or traces of oil / brake fluid on them, determine the source of leakage / reason for the operation of the shoe and eliminate the malfunction before proceeding with the assembly of the mechanism.
5. Description of the procedure for replacing the brake shoes is given in the following paragraphs. If no defects are found, reinstall the brake drum (see Section Removal, check of a condition and installation of drums of brake mechanisms of back wheels).
6. Mark the position of the components in the brake drum, paying special attention to the order of placement of the adjusting wedge, expansion bar and various springs.
7. Remove the shoe guide spring cups by pressing them down with pliers and turning them 90°...
... after removing the cups, remove the springs and anchor pins
8. After removing the shoes from their lower axles one at a time, loosen the lower return spring, then unhook it from both shoe assemblies.
9. Release the upper ends of the shoes from the pistons of the wheel cylinder - try not to damage the piston cuffs. Disconnect the parking brake cable from the rear shoe. Now the shoe assembly can be removed from the brake shield complete with the expander bar.
Note. Do not depress the foot brake pedal until the shoes are in place. To fix the pistons, wrap the wheel cylinder assembly on the outside with an elastic bandage tape.
10. Try to remember the installation position of all components, then disconnect the spring from the expander wedge and remove it from the shoe assembly.
11. Disconnect the upper return spring and release from the expansion bar, remove the rear shoe.
12. Remove the expansion wedge (try to remember its installation position), then remove the expansion bar and unhook the compressing spring.
13. Check all components for signs of wear and mechanical damage. Replace defective parts. Both return springs must be replaced without fail, regardless of their condition. Although friction linings can in principle be purchased individually, the compilers of this Guide recommend replacing worn shoe assemblies.
14. Turn back rubber boots and check the wheel cylinder for signs of leaks and mechanical damage. Assess the freedom of movement of both pistons. Information on the overhaul of wheel cylinders is set out in Section Removal, overhaul and installation of front wheel brake calipers.
15. Lightly lubricate the contact surfaces of the expansion bar and the parking brake actuating lever with special brake grease.
16. Connect the compress spring to the front shoe. Hook the opposite end of the spring to the expander bar, which then slide into the front shoe mounting groove.
17. Insert the spacer wedge into its proper place between the front shoe and the pusher of the adjusting mechanism. Make sure the components are installed correctly.
18. Connect the top return spring to the front shoe. Hook the second end of the spring in the hole of the rear shoe, making sure that the hooks of the spring fit correctly, thread the rear shoe into the fork of the expander bar. Track correct engagement with a level of both boots and the executive lever of a lay brake.
19. Install spring between adjuster wedge and front shoe.
20. Before installing the shoe assembly, thoroughly wipe the surface of the brake shield and lightly lubricate all surfaces in contact with the shoes with high-temperature brake grease or anti-seize sealant, paying particular attention to the wheel cylinder pistons and the lower axial shoe landing sites. Do not allow grease to get on the surfaces of the friction linings and the working walls of the drum.
21. Remove the elastic bandage from the wheel cylinder and slide the shoe assembly into place.
22. Connect the drive cable to the parking brake actuating lever, then tuck the top ends of the shoes into the grooves in the ends of the wheel cylinder pistons.
23. Attach the bottom return spring to the shoes, then slide the bottom of the shoes onto the bottom anchor assemblies.
24. Tap the shoes to shrink them on the brake shield, then install the anchor pins and guide springs, fixing the latter with cups.
25. Reinstall the brake drum (see Section Removal, check of a condition and installation of drums of brake mechanisms of back wheels).
26. Repeat the procedure for the second brake mechanism.
27. After replacing the entire set of shoes, fully release the parking brake and adjust the working clearance between the surfaces of the friction linings of the shoes and the working wall of the drum. Adjustment is made by depressing the foot brake pedal until the pressure in the system is fully restored.
28. Check the proper operation of the parking brake, if necessary, adjust its drive accordingly (see Section Parking brake adjustment).
29. Finally, check the brake fluid level in the GTZ reservoir.
Attention! Full braking performance is only achieved after the final running-in of the new brake shoes. Avoid sudden braking during the first hundred kilometers after replacing brake components.