Contents: Disassembly ↓ Assembly ↓
Disassembly
1. Remove the protective caps 2 (see Fig. Wheel cylinder), then press out pistons 4 from the cylinder body together with the parts of the automatic clearance adjustment device between the brake shoes and the drum.
2. Install the piston assembly with the automatic device on a special fixture so that the projections of the fixture enter the grooves of the stop screw 3 (see Fig. Wheel cylinder parts). Using a special screwdriver, turn piston 9 and unscrew stop screw 3 from the piston. Remove seal 8 with support cup 7 and crackers 5 from the screw. Disconnect stop ring 4 and stop screw 3.
Assembly
1. Assemble the automatic device and the wheel cylinder itself in reverse order.
2. Tighten the piston stop screws to a torque of 3.9–6.8 N·m (0.4–0.7 kgf·m).
3. Slot A (see fig. Wheel cylinder) on the thrust rings must be directed vertically upwards, the deviation from the vertical is allowed no more than 300. This location of the slot ensures more complete removal of air from the brake mechanism drive of the wheel when bleeding the brake.
4. To pre-compress the thrust rings, press the pistons into the cylinder body using a special device shaped like a cylinder with a conical inner hole.
5. The force for pressing the piston into the cylinder must be at least 343 N (35 kgf); if the force is less than 343 N (35 kgf), replace the thrust ring.
6. When pressing the piston into the cylinder, it is necessary to maintain dimensions of 4.5–4.8 mm and 67 mm (maximum) (see fig. Wheel cylinder) for free fit of the brake drum.
7. Before installing the parts into the cylinder body, lubricate them generously with brake fluid.
8. After assembly, check the movement of each piston in the cylinder body. They should move easily within 1.25–1.65 mm. Lastly, install protective caps 2 in place (see Fig. Wheel cylinder).