Replacing seals
To inspect and replace the seals, it is not necessary to remove the wheel cylinder from the brake shield. Removing the cylinder is only necessary for its complete replacement due to wear or damage to the housing.
Replace the wheel cylinder seals in the following order:
1. Remove the brake drum and brake shoes from the brake shield as described in the previous section.
2. Clamp the brake hose in front of the rear axle using a special clamp or clamp.
3. Clean the outside of the cylinder and the mating surfaces.
4. Remove the rubber dust boots from both ends of the cylinder and remove the pistons and spring from the cylinder bore (drawing O:20).
5. Remove the rubber seal from each piston.
6. Wash all parts in clean brake fluid or methylated spirits, then dry them with a lint-free cloth. Check the piston surfaces and cylinder bores for burrs and scratches; if any are found, replace the part.
7. If the pistons and cylinder are in good condition, assemble the cylinder as follows:
8. Lubricate the pistons, new seals and cylinder with clean brake fluid.
9. Install a new seal on each piston with the flat surface facing the inside of the groove.
10. Insert one of the pistons, seal first, into the cylinder, being careful not to damage the sealing lip.
11. Insert the spring and the second piston into the other end of the cylinder.
12. Install new rubber boots on the ends of the cylinder and place them on the central projections of the pistons.
13. Install the brake shoes on the brake shield, then install the brake drum as described earlier.
14. Remove the clamp from the brake hose and bleed the brakes.
Wheel cylinder replacement
1. Remove the brake drum and brake shoes (see above).
2. Clamp the brake hose in front of the rear axle using a special clamp.
3. Disconnect the brake pipe from the back of the wheel cylinder.
4. Remove the two bolts securing the cylinder to the brake shield and remove the wheel cylinder. Use a 5mm Allen key to remove the bolts.
5. Plug the open end of the brake pipe to prevent dirt from entering.
6. The wheel cylinder is installed in the reverse order.
7. To make it easier to connect the brake pipe, screw the pipe nipple into the cylinder before inserting the cylinder mounting bolts. Finally tighten the pipe after tightening the brake cylinder bolts.
8. Assemble the brake shoes on the brake shield and install the brake drum.
9. Remove the clamp from the brake hose and bleed the brakes as described earlier.
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