• Low fluid in reservoir
  • Excessive brake lining wear
  • Incorrect brake adjustment
  • Faulty disc brake adjustment
  • Cracked brake drum
  • External leaks at pipe unions
  • Leakage past rubber seals in master cylinder, wheel cylinders or calipers
  • Leaking brake servo
  • Worn clevis pin on pedal linkage
  • Distorted damping shims
  • Excessive free play at pedal
  • Air in system
  • Ballooning brake hose


  • Air in system
  • Warped drums or rotors
  • Loose caliper or backing plate
  • Sticking wheel cylinder piston
  • Wheel cylinder leaking
  • Loose wheel bearings
  • Defective brake servo
  • Incorrect brake linings
  • Adjuster pin loose
  • Shoe retainer loose
  • Dust in brake drums
  • Retraction spring broken
  • Brake shoe friction material has separated
  • Clogged brake line
  • Failed brake hose
  • Mismatched tires
  • Contaminated brake linings
  • Loose rear spring, axle or U-bolts


  • Air in hydraulic system
  • Brake shoe friction material has separated
  • Distorted brake drums or discs
  • Uneven tire inflation
  • Mixed tire types
  • Brake caliper or back plate loose
  • Worn steering gear
  • Brake shoes incorrectly fitted
  • Rear spring or axle bolts loose
  • Loose wheel bearing
  • Grease or oil on brake linings
  • Sluggish wheel cylinder piston
  • Grease on brake disc
  • Wheel cylinder leaking
  • Clogged brake line
  • Flattened or crimped brake line
  • Failed brake hose


  • Linings not bedded in
  • Brake drum cracked
  • Master cylinder loose
  • Bulkhead flexing


  • Low fluid in reservoir
  • Master cylinder main cup worn
  • Perished master cylinder seals
  • Leak past the master cylinder secondary cup
  • Defective hose
  • Air in hydraulic system
  • Wheel cylinder leaking
  • Fault in brake servo


  • Partially seized piston in master cylinder or wheel cylinder
  • Oil or brake fluid on linings
  • Binding pedal
  • Incorrect type of brake lining fitted
  • Inadequate brake servo action
  • Brakes not properly bedded in
  • Seized caliper


  • Worn rotors
  • Worn discs
  • Worn pads


  • Disc corroded or scored
  • Incorrect pads installed
  • Hydraulic seals deteriorated


  • Hydraulic seals deteriorated

The Braking System

When the brake pedal is depressed, the brakes convert the vehicle’s forward motion into heat energy through the use of friction applied at the wheels causing the car to slow down or stop. The amount of friction created is proportional to the pressure between the surfaces in contact independent of the surface area.

Because the vehicle must come to a stop in a much shorter time than is required to reach a given speed, tremendous forces are involved whenever the brakes are applied. As the vehicle speed increases, the kinetic energy that must be transformed into heat also increases. If the vehicle speed doubles, four times as much power is required to stop the car, with the brakes having to absorb and dissipate the heat generated.

Although work on the development of disc brakes began in England in the late 19th Century and saw a patent issued for the first caliper-type disc brake design in 1902, it wasn’t until the postwar era that such an advanced system became a viable option to replace the venerable hydraulic drum brake. Because liquid is a virtually incompressible medium, automobiles had adopted hydraulic systems during the Depression-era to operate the brakes in a safer and more reliable manner than was possible with purely mechanically operated brakes, using pistons in the master cylinder to force hydraulic fluid throughout the system and into cylinders located at each wheel. The pressurized fluid causes the pistons in the cylinder to move, forcing the friction material against a drum or rotor to retard forward motion.
The Dunlop caliper-type disc brake first appeared for competition use on the Jaguar C-type in 1953, before it was adopted for use in the Austin-Healey 100S and the later Jensen 541. In 1957, Triumph’s TR3 pioneered the first use of front disc brakes for affordable mass-production sports cars, leading the way to widespread use in almost every other British sports car produced by the end of the decade.