Three main factors influence the braking process:
- on different wheels there will be different conditions for the adhesion of tires to the road, which causes different braking forces. Air pressure and tire tread must be the same;
- braking forces on the front and rear axles must be proportional to the vertical loads acting on them;
- misalignment of the wheels can cause the vehicle to pull to the side when braking.
To check for brake fluid leakage, depress the brake pedal with the engine running at idle speed and the transmission shift lever in neutral. If the pedal drops gradually at constant pressure, there is a leak in the system. Visually check for leakage and brake fluid level in the master cylinder reservoir. A slight drop in the brake fluid level is due to normal pad wear. An abnormally low level indicates a leak in the system. In a hydraulic system, both internal and external leakage is possible. If the brake fluid level is normal, check the length of the brake booster rod. If improper stem length is found, adjust length or replace stem.
Check the brake master cylinder in the following order:
- for damage and leakage of brake fluid around the brake master cylinder. A low brake fluid level can only indicate a leak. It is also abnormal to wet the surface of the brake master cylinder;
- pedal linkage and stem length. If they are normal, disassemble the master cylinder and check for stretching or swelling of the cylinder seals, then for wear on the rubber parts. If the seals are swollen, a 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 replaced. All pipelines should also be flushed.
Incorrect brake fluid, mineral oil, or water in the fluid can cause the brake fluid to boil or damage rubber components. If the main piston seals in the master cylinder are swollen, then the rubber components are damaged. If rubber wear is found, disassemble all parts of the hydraulic system and flush them with alcohol. Dry the parts with compressed air before assembling. Replace all rubber parts in the system, including hoses. During the operation of the brake mechanism, check the absence of fluid in the gaskets. If fluid is found, replace gaskets.
If the brake master cylinder piston seals are in good condition, check for leakage or excessive overheating. If these conditions are not found, drain the brake fluid, fill the brake master cylinder and re-drain the system.