Wheel cylinder parts
1 – protective cap; 2 – piston; 3 – seal; 4 – wheel cylinder housing; 5 – spring cups; 6 – air release nipple; 7 – spring;
Wheel cylinders
1. To check the wheel cylinders, disassemble: remove the protective caps 1 (see fig. Wheel cylinder parts) and pistons 2, remove seals 3, support cups 5 and spring 7, then unscrew air release nipple 6.
2. Check the cleanliness of the working surfaces of the cylinder and pistons.
3. The surfaces must be completely smooth, without scratches or roughness, to prevent fluid leakage and premature wear of pistons and seals.
4. Eliminate defects on the cylinder mirror by grinding or polishing. However, increasing the internal diameter of the cylinder is not allowed.
5. Check the elasticity of the spring. Its length in a free state should be 34 mm, under a load of 35±2 N (3.5±0.2 kgf) – 17.8 mm. Replace it if necessary.
6. Replace the seals with new ones.
7. Also check if the cylinder protective caps are damaged and replace them with new ones if necessary.
8. Before assembly, generously lubricate all parts with brake fluid. In the sequence shown in Fig. Fig. Wheel cylinder parts, install the parts into the cylinder body without force, so as not to damage the rubbing surfaces.
9. Install the protective caps.
10. Using both hands, check the piston movement, which should be smooth and without sticking.
Pads
1. Check the pads carefully for damage or deformation.
2. Check the elasticity of the tension springs, both upper and lower; replace them with new ones if necessary. The springs should not have any residual deformations when stretched with a force of 343 N (35 kgf) for the lower springs and 412 N (42 kgf) for the upper springs.
3. Check the cleanliness of the linings, if dirt or traces of grease are found, thoroughly clean the linings with a metal brush and wash with white spirit, in addition, check for grease or oil leaks inside the drum; please fix the problems.
4. Replace the pads with new ones if the thickness of the linings has become less than 1.5–2 mm.
Brake drums
1. Inspect the brake drums. If there are deep scratches or excessive ovality on the working surface, ream the drums on a machine.
[The article is taken from an online resource: VAZbook.ru]
2. Then, on a lathe, grind the drums with fine-grained abrasive bars. This increases the durability of the linings and improves the uniformity and efficiency of braking. The greatest permissible increase in the nominal diameter of the drum (250 mm) after boring and grinding is 1 mm. The limits of this tolerance must be strictly observed, otherwise the strength of the drum, as well as the braking efficiency, are impaired.