During the process of overhauling the Brake Master Cylinder, it is very vital to replace the cylinder body rather than honing the bore, because honing will damage the hard and polished surface and it causes rapid wear of the rubber cups. You must start by removing the master cylinder brake fluid reservoir, followed by removing the snap-ring, and lastly, removing the primary
Piston assembly from the master cylinder body. In the case of using air pressure to evacuate the secondary Piston, make sure the open end of the cylinder bore is roughly 25mm (1 inch) from a padded surface so the Piston can be caught and depressurize it slowly with caution, while never pointing the bore at anyone. After removing the secondary Piston, plug the rear port and apply small air pressure on the front one and this makes it easier to remove the seals and the spring retainer with the spring from the master cylinder body. Clean the parts with no-time alcohol for metal parts, and clean-brake solvent for rubber parts, using only the approved solvents that will not damage the rubber components. Examine the diaphragm to see whether it has cuts or cracks and swelling; examine the cylinder bore for scoring or corrosion with the possibility of replacing the master cylinder in case there is corrosion. Lubricate the grommets, seals, and the cylinder bore with clean brake fluid, with new seals during assembly. Position the spring and spring retainer, then position primary seal and secondary seal on the secondary Piston and insert the secondary Piston and primary Piston assembly into the master cylinder body. Finally, install the snap ring by compressing the primary Piston, and reattach the master cylinder brake fluid reservoir.