Pic. 6.32. Front Disc Brake Components: 1 - guide pin; 2 - guide pin; 3 - bushing; 4 - caliper bracket (with brake pads); 5 - anther; 6 – anther collar; 7 - piston boot; 8 - piston; 9 - piston sealing ring; 10 - support; 11 - brake shoe and wear indicator in the assembly; 12 - brake shoe assembly; 13 - outer gasket; 14 - latch
Front disc brake components are shown in fig. 6.32.
Pic. 6.33. Map of lubrication points
Disassembly
Pic. 6.34. Piston removal
Apply compressed air to the brake hose opening to remove the piston and piston boot (pic. 6.34). Remove the piston o-ring and piston.
Attention! Use the handle of a plastic hammer to remove the piston. Apply air gradually so that when the pistons are removed from the caliper, their tops are always at the same level.
Attention! Remove the primary and secondary pistons only at the same time, otherwise the secondary piston may warp during removal.
Pic. 6.35. Removing the piston seal
Remove the piston o-ring with your finger (pic. 6.35).
Attention! To prevent damage to the inner surface of the working brake cylinder, do not use a flathead screwdriver or other tool.
Wash piston and cylinder surfaces with trichlorethylene, alcohol, or recommended brake fluid.
Used brake fluid: DOT3 or DOT4.
Examination
Check the brake cylinder for signs of wear, damage and rust.
Check the surface of the brake cylinder piston for signs of wear, damage and rust.
Check the caliper bracket and bushing for signs of wear.
Check the brake pad linings for damage or oil, and the metal backings of the pads for damage.
Pic. 6.36. Extraction of brake pad thickness
Measure the thickness of the brake pad lining at the point of greatest wear. If the thickness of the brake pad lining is less than the limit, replace the brake pads (pic. 6.36).
Assembly
Rinse all parts (except for brake pads and brake pad gaskets) isopropyl alcohol.
Install the piston o-ring.
After that, apply the recommended brake fluid to the outer surface of the piston, install the piston into the brake cylinder.
Pic. 6.37. Boot Installation Diagram
Install the piston boot and boot collar (pic. 6.37).
Install the guide pin boots and guide pins.
Install pads and brake cylinder.
Connect the brake hose to the caliper.
Clamping screw tightening torque: 7–9 Nm.
Fill the brake fluid reservoir with brake fluid.
Remove air from the brake hydraulic drive.