Disassembly
1. Remove protective caps 2 (see fig. wheel cylinder), then press the pistons 4 complete with the parts of the device for automatically adjusting the gap between the brake shoes and the drum from the cylinder body.
2. Install the piston assembly with the automatic device on a special tool so that the protrusions of the tool fit into the grooves of the stop screw 3 (see fig. Wheel cylinder parts). Using a special screwdriver, turning the piston 9, unscrew the stop screw 3 from the piston. Remove the seal 8 with the support cup 7 and crackers 5 from the screw. Separate the thrust ring 4 and the thrust screw 3.
Assembly
1. Assemble the automatic device and the wheel cylinder itself in the reverse order.
2. Tighten the thrust screws of the pistons with a torque of 3.9–6.8 Nm (0.4–0.7 kgf·m).
3. slot A (see fig. wheel cylinder) on the thrust rings should be directed vertically upwards, the deviation from the vertical is allowed no more than 300. This arrangement of the slot provides a more complete removal of air from the wheel brake drive when bleeding the brake.
4. To pre-compress the thrust rings, press the pistons into the cylinder body with a special tool that has the shape of a cylinder with a tapered inner hole.
5. The force of pressing the piston into the cylinder must be at least 343 N (35 kgf), with a force of less than 343 N (35 kgf) replace thrust ring.
6. When pressing the piston into the cylinder, it is necessary to maintain the dimensions 4.5–4.8 mm and 67 mm (maximum) (see fig. wheel cylinder) for free fit of the brake drum.
7. Before installing parts in the cylinder body, lubricate them liberally 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. Replace protective caps 2 last (see fig. wheel cylinder).