Master Cylinder Overhaul

DISASSEMBLY PROCEDURE

NOTICE: Do not hone the master cylinder bore. When the brake master cylinder is overhauled, it is recommended that the cylinder body be replaced rather than CLEANED UP by honing the bore. The master cylinder has a hard, highly polished BEARINGIZED surface, which is produced by diamond boring followed by ball or roller burnishing under heavy pressure. Honing will destroy this hard smooth surface and cause rapid wear of the rubber cups.

1. Remove the cover.
2. Remove the diaphragm.





3. Drain the brake fluid from the reservoir.
4. Remove the reservoir and two grommets from the master cylinder body.
5. Clamp the master cylinder mounting flange in a vise. Pry the reservoir off with a bar.
6. Remove the snap ring.





7. Remove the primary piston assembly from the master cylinder body.

CAUTION: If air pressure Is used to remove the secondary piston, place the open end of the cylinder bore approximately 25 mm (1 inch) from a padded workbench or other surface to catch the piston when It comes out of the bore. Apply low air pressure very carefully to ease the piston out of the bore. Never point the open end of the bore at anyone when applying air pressure. The piston may come out of the bore with considerable force and cause personal Injury.





8. Remove the secondary piston from the master cylinder body.
Plug the rear port. Apply a small amount of air pressure to the front port.
9. Remove the seals.
10. Remove the spring retainer and the spring from the master cylinder body.

NOTICE: Use approved solvents only when cleaning or flushing the master cylinder and related components. The use of these liquids as cleaning solvent will damage the rubber parts in the system if they have any trace of mineral oil or other contaminants.

11. Clean all the parts using the following procedure:
^ Clean the metal parts in denatured alcohol.
^ Clean the rubber parts in clean brake fluid.
12. Check the diaphragm for cuts, cracks, or swelling.
13. Inspect the cylinder bore for scoring or corrosion.
^ Replace the master cylinder if corrosion is present.
^ Do not attempt to hone the cylinder bore.
14. Check the reservoir for cracks.

ASSEMBLY PROCEDURE





1. Lubricate the grommets, seals, and the cylinder bore with clean brake fluid.
2. Use new seals when assembling the master cylinder.
3. Install the spring.
4. Install the spring retainer.





5. Install the primary seal on the secondary piston.
6. Install the secondary seal on the secondary piston.





7. Install the secondary piston in the master cylinder body.
8. Install the primary piston assembly in the master cylinder body.
9. Install the snap ring.





10. Compress the primal piston in order to install the snap ring.





11. Install two new grommets to the master cylinder.
12. Install the reservoir on the master cylinder body.
13. Press on the body while using a rocking motion.





14. Install the diaphragm in the cover.
15. Install the cover on the reservoir.