Wheel cylinders
Check the cleanliness of the working surfaces of the cylinder, pistons and thrust rings. Surfaces must be perfectly smooth and free of roughness to prevent fluid leakage and premature wear of seals and pistons. Irregularities on the cylinder mirror should be eliminated by lapping or grinding, however, an increase in the inner diameter of the cylinder is not allowed.
Check the condition of the stop screw 3 (see fig. 205), spring 6, support cup 7 and crackers 5. If necessary, replace damaged parts with new ones. Replace the seals 8. Check the condition of the protective caps 10 and replace them if necessary.
Pads. Carefully check the pads for damage or deformation. Check the elasticity of the upper and lower coupling springs; replace them if necessary. The springs should not have residual deformations when stretched with a force of 35 kgf of the lower springs and 42 kgf of the upper ones. Check the cleanliness of the linings, if dirt or traces of grease are found, clean the linings with a wire brush and rinse with white spirit, in addition, check if there is any leakage of grease inside the drum; eliminate the found faults. Replace the pads with new ones if the thickness of the pads has become less than 1.5-2 mm.
Brake drums
Inspect the brake drums. If there are deep risks or excessive ovality on the working surface, then bore the drums, and then grind them with bars on a lathe (grain size 10-16). This increases the durability of the linings and improves braking uniformity and efficiency. The largest allowable increase in the nominal diameter of the drum (250 mm) after boring and grinding 1 mm. This requirement must be observed, otherwise the strength of the drum is violated. The limiting diameter of a worn drum is 251.6 mm.