Disassembly of the brake master cylinder
1. Clean the outside of the master cylinder, push the secondary piston inward and remove the retaining ring;
2. Remove the liquid storage tank, push the secondary piston in, remove the positioning pin, and then remove the secondary and primary piston;
3. Remove the rubber retaining ring from the liquid storage tank and the liquid storage sealing ring from the liquid storage tank cover;
4. Draw out the brake fluid from the brake fluid reservoir;
5. Disconnect the brake hard pipe connected to the brake master cylinder;
6. Remove the brake master cylinder from the vacuum booster or brake diaphragm;
7. Check whether the vacuum booster is contaminated with brake fluid, and replace it if necessary;
8. Check that the check valve is working properly and replace it if necessary.
To check the wear of the cylinder hole of the master cylinder, the piston can be placed in the cylinder of the master cylinder, and the gap between the piston and the cylinder hole can be checked with a feeler gauge. If the gap is too large (greater than 0.15mm), the pump assembly must be replaced. Due to the working characteristics of the master cylinder, the front end of the piston wears more than the rear end, and the inner half of the cylinder bore wears more than the outer half. Therefore, when measuring the fit clearance, the piston should be turned upside down and placed in the cylinder bore, measured with a feeler gauge at the point of maximum wear.
The wall surface of the cylinder hole of the master cylinder must be smooth and free of rust. If there are slight scratches and spots on the wall surface, you can use a fine emery cloth to polish it, and you can not use sandpaper to grind it. If the score is deep, the master cylinder should be replaced. Check whether the storage tank is damaged or aging, check whether the filter screen is blocked, and remove the accumulated sediment.
Check the liquid filling cap: check whether the vent hole of the liquid storage cap is blocked, and make it clear; check whether the buoy can move up and down freely; if not, replace the liquid storage tank assembly; The buoy is placed in the descending position and the ascending position to measure the continuity between the terminals; when the buoy rises, it should be non-conducting. When the buoy drops, it should be turned on. Replace rubber guard ring, push rod seal ring, circlip, primary piston, secondary piston and their cups.