Table 11.2. Diagnostics of brake system faults
| Malfunction | Cause of malfunction | Methods of elimination |
| Uneven action of the brake mechanisms of the wheels of one axle | a) the tire pressure does not correspond to the prescribed one | a) adjust the tire pressure |
| b) uneven wear of the tread pattern | b) swap tires, replace tires | |
| c) oiling of brake shoe linings | c) replace the brake pads, find out the cause | |
| d) incorrect type of pads | d) replace the brake pads, find out the cause | |
| d) contamination of the floating support grooves | d) remove and clean the floating calipers | |
| e) contamination or damage to the guide pins | e) replace the guide pins | |
| g) incorrect geometry of the rear suspension | g) measure wheel alignment angles | |
| c) corrosion damage to floating calipers or wheel brake cylinders | c) remove the calipers or wheel brake cylinders, repair them or replace them | |
| i) shock absorber malfunction | i) check the shock absorber, replace if necessary | |
| c) wear of the linings of one of the calipers | c) replace brake pads check floating caliper | |
| l) insufficient roughness of the linings | l) replace brake pads, check floating caliper | |
| Brakes overheat while driving | a) clogging of the compensation hole in the master cylinder | a) overhaul the main brake cylinder, replace if necessary |
| b) there is no gap between the piston rod and the master cylinder piston | b) adjust the rod (in old cars) | |
| c) swelling of rubber parts due to the use of the wrong brand of brake fluid | c) overhaul the main brake cylinder, replace if necessary | |
| d) clogging of the ventilation hole in the master cylinder reservoir | d) clean the master cylinder reservoir | |
| d) corrosion of floating calipers | d) remove the floating calipers, repair them or replace them | |
| e) the expansion spring is broken | e) replace the expansion spring | |
| g) the parking brake is not fully released | g) check the parking brake and its cables; repair if necessary | |
| Weak action of the service brake despite increased force applied to the brake pedal. Normal brake pedal travel | oily or burnt brake pads, incorrect type of pads | replace brake pads |
| Weak action of the service brake despite increased pedal pressure. Shortened brake pedal travel | the booster does not work - the vacuum created by the engine is not sufficient | check brake booster - check engine (valves, cylinder head gasket, etc.) |
| Weak action of the service brake despite increased pedal pressure. Increased pedal travel | failure of the brake drive circuit due to depressurization or damage | check the tightness of the brake system |
| The brake pedal fails | a) air in the brake system | a) top up or replace brake fluid, bleed the brake system |
| b) not enough brake fluid in the reservoir – as a) | b) top up or replace brake fluid, bleed the brake system | |
| c) overheating of brake fluid – boiling (steam bubbles) due to increased water content in the brake fluid or overloading of the brakes | c) top up or replace brake fluid, bleed the brake system | |
| The brake hydraulic system has been bled and adjusted, but the brake pedal still sinks | a) damage to the primary cuff of the master cylinder | a) overhaul or replace the master brake cylinder |
| b) leakage of the intermediate cuff on the floating piston of the two-cavity master brake cylinder | b) overhaul or replace the master brake cylinder | |
| c) leak in the brake system | c) check the tightness of the brake system | |
| Uneven wear of brake pads | a) incorrect type of pads | a) replace the brake pads |
| b) contamination of the floating support grooves, damage to the protective covers | b) remove the calipers or wheel brake cylinders, repair them or replace them | |
| c) corrosion damage to floating calipers or wheel brake cylinders | c) remove the calipers or wheel brake cylinders, repair them or replace them | |
| d) swelling of the rubber piston adjusting ring | d) remove the calipers or wheel brake cylinders, repair them or replace them | |
| One-sided wear of brake pads | a) increased wheel hub bearing clearance | a) replace the wheel hub bearing |
| b) misalignment of the brake disc and floating caliper mount | b) check the mounting of the floating caliper | |
| c) corrosion damage to floating calipers or wheel brake cylinders | c) remove the calipers or wheel brake cylinders, repair them or replace them | |
| d) one-sided wear of the brake disc | d) polish or replace brake discs | |
| d) the thickness of the brake pads is less than the minimum permissible | d) replace the brake pads | |
| e) insufficient pressure of the retaining spring | e) replace the retaining spring | |
| g) damage to guide pins | g) replace the guide pins | |
| Brake pads sticking to the brake disc | a) contamination of the floating support grooves, damage to the protective covers | a) remove the floating calipers, repair them or replace them |
| b) corrosion of floating calipers | b) remove the floating calipers, repair them or replace them | |
| c) clogging of the compensation hole in the master cylinder | c) overhaul or replace the master brake cylinder | |
| Squealing and crackling brakes | a) incorrect type of pads | a) replace the brake pads |
| b) contamination of the floating support grooves | b) remove and clean the floating calipers | |
| c) insufficient pressure of the retaining spring | c) replace the retaining spring | |
| d) misalignment of the brake disc and | d) check the mounting of the floating caliper | |
| d) brake disc runout | d) check the brake discs for runout and replace them if necessary | |
| e) the difference in disk thickness within the working surface is higher than the permissible value | e) measure the thickness of the brake discs, grind or replace the discs | |
| g) ovality of brake drums | g) grind or replace brake drums | |
| c) beating of brake drums | c) grind or replace brake drums | |
| i) dirt and dust in the brake drums | i) clean and check the brake drums | |
| c) increased or one-sided wear of the pads | c) replace the parking brake shoes | |
| l) rusty edges of brake discs | l) polish or replace brake discs | |
| m) the shoe is not secured | m) replace brake pads | |
| n) increased wheel hub bearing clearance | n) replace the wheel hub bearing | |
| Increased free travel of the brake pedal | a) increased wheel hub bearing clearance | a) replace the wheel hub bearing |
| b) misalignment of the brake disc and floating caliper mount | b) check the mounting of the floating caliper | |
| c) brake disc runout | c) check the brake discs for runout and, if necessary, replace them | |
| d) the difference in disk thickness within the working surface is higher than the permissible value | d) measure the thickness of the brake discs, grind or replace the discs | |
| d) the brake system is leaky | d) check the tightness of the brake system | |
| e) air in the brake system | e) bleed the brake system | |
| g) incorrect type of pads | g) replace the brake pads or replace the parking brake pads | |
| c) automatic brake pad adjustment does not function | c) remove the parking brake shoes and restore the adjustment | |
| Pistons seizing in the caliper | a) contamination of the floating support grooves, damage to the protective covers | a) remove the floating calipers, repair them or replace them |
| b) misalignment of the brake disc and floating caliper mount | b) check the mounting of the floating caliper | |
| c) corrosion of pistons in floating calipers or wheel brake cylinders | c) remove the caliper or wheel brake cylinder, repair it or replace it | |
| Brake pedal pulsation | a) increased wheel hub bearing clearance | a) replace the wheel hub bearing |
| b) misalignment of the brake disc and floating caliper mount | b) replace the floating caliper mount | |
| c) brake disc runout | c) replace the brake discs | |
| d) the difference in disk thickness within the working surface is higher than the permissible value | d) measure the thickness of the brake discs, grind or replace the discs | |
| Insufficient parking brake performance | a) oiling of brake pads | a) replace brake pads, determine the cause |
| b) increased free play between the brake shoes and the brake drum | b) adjust the parking brake | |
| c) increased free travel of cables | c) adjust the parking brake | |
| d) incorrect adjustment of cables | d) adjust the parking brake | |
| d) corrosion of transmission elements | d) remove the parking brake and release mechanisms, check and, if necessary, replace the cables |