Wheel cylinders
1. Check the cleanliness of the working surfaces of the cylinder, pistons and thrust rings.
2. Surfaces must be perfectly smooth and free of roughness to prevent fluid leakage and premature wear of seals and pistons.
3. Eliminate defects on the cylinder mirror by lapping or grinding. However, an increase in the inner diameter of the cylinder is not allowed.
4. Check the condition of the stop screw 3 (see fig. Wheel cylinder parts), springs 6, cup support 7 and crackers 5. If necessary, replace damaged parts with new ones.
5. Replace seals 8 with new ones. Check the condition of the protective caps 10 and replace them if necessary.
Pads
1. Carefully check the pads for damage or deformation.
2. Check the elasticity of the coupling springs, both upper and lower; replace them if necessary.
3. Springs should not have permanent deformations when stretched with a force of 343 N (35 kgf) lower springs and 411 N (42 kgf) - upper.
4. Check the cleanliness of the pads; if dirt or traces of grease are found, carefully clean the linings with a wire brush and rinse with mineral spirits, in addition, check for grease or oil leaks inside the drum; troubleshoot.
5. Replace the pads with new ones if the lining thickness is less than 1.5–2 mm.
Brake drums
1. Examine them. If there are deep grooves or excessive ovality on the working surface, bore the drums on the machine.
2. Then, on a lathe, grind the drums with abrasive fine-grained bars. This increases the durability of the linings and improves braking uniformity and efficiency.
3. The largest allowable increase in the nominal diameter of the drum (250 mm) after boring and grinding 1 mm. The limits of this tolerance must be strictly observed, otherwise the strength of the drum is violated, as well as the effectiveness of braking.