There are three main factors that influence the braking process:
- different wheels will have different conditions of tire adhesion to the road, which will cause different braking forces. Air pressure and tire treads should be the same;
- the braking forces on the front and rear axles must be proportional to the vertical loads acting on them;
- misalignment of the wheels may cause the vehicle to pull to the side when braking.
To check for a brake fluid leak, press the brake pedal with the engine running at idle speed and the gearshift lever in neutral. If the pedal gradually sinks under constant pressure, there is a leak in the system. Visually check for a leak and the brake fluid level in the brake master cylinder reservoir. A slight drop in the brake fluid level is due to normal wear of the brake pads. An abnormally low level indicates a leak in the system. Both internal and external leaks are possible in a hydraulic system. If the brake fluid level is normal, check the length of the brake booster piston rod. If an improper piston rod length is found, adjust the length or replace the piston rod.
Check the brake master cylinder in the following order:
- for damage and leakage of brake fluid around the master cylinder. A decrease in the brake fluid level can only indicate the presence of a leak. Wetting of the surface of the master cylinder is also an abnormal condition;
- pedal rod connection and rod length. If they are normal, disassemble the master brake cylinder and check for stretching or swelling of the cylinder seals, then for wear of the rubber parts. If the seals are swollen, non-standard or contaminated brake fluid may be used. If contaminated brake fluid is found, all metal components should be disassembled and cleaned, and all rubber components should be replaced. All pipelines should also be flushed.
Inappropriate brake fluid, mineral oil, or water in the fluid can cause the brake fluid to boil or damage the rubber components. If the main piston seals in the master cylinder are swollen, the rubber components are damaged. If rubber wear is detected, disassemble all hydraulic system components and wash them with alcohol. Dry the components with compressed air before reassembling. Replace all rubber components in the system, including hoses. When the brake mechanism is operating, check for fluid in the gaskets. If fluid is detected, replace the gaskets.
If the master cylinder piston seals are normal, check for leaks or excessive overheating. If these conditions are not found, drain the brake fluid, refill the master cylinder, and drain the system again.