Understanding and preventing brake noise

When the Beach Boys were singing about ‘Good Vibrations’, they definitely weren’t referring to the braking system. When vibrations occur between the brake pad, brake disc and caliper, the resultant brake squeal can make any driver wish they too could be on the beach, far away from that irritating high pitched noise.

Causes of brake noise

There are many causes for brake squeal. Excessive corrosion, seized or bent location pins, partially seized calipers, built up dirt and brake dust or worn brake discs can cause vibration between the brake disc and the brake pad under braking conditions. Any vibration within the brake set up will result in noise being generated, which is often referred to as brake pad squeal. Glazing of the friction material surface may also contribute to brake noise. Manufacturers of braking systems and friction materials have taken extensive measures to suppress brake noise in recent years.

Improvements to reduce brake noise

Demands for higher performance and overall weight reduction on modern vehicles have led to material changes. This has resulted in the increased use of supplementary processes to counteract vibrations. Noise fixes include the addition of shims, slots, chamfers and underlayers within the friction material. For example, Delphi carefully selects friction materials, using more than 19 different compounds in their brake pad product line to ensure the closest possible match to OE comfort characteristics and performance. These compounds are developed to provide consistently high levels of performance.

All Delphi brake pads also incorporate underlayer technology. This is a process used by many OE manufacturers to dampen noise-producing vibrations and ensure a higher bonding strength with the pad back plate. Delphi brake pads also feature shims, slots and chamfers that match OE specifications and provide superior performance and durability.

Brake installation tips

Whilst we’re on the subject of braking, here are some handy installation tips.

  • Ensure that all corrosion, built up dirt and brake dust is removed from the caliper. Ensure that moving parts of the caliper are free to slide.
  • Always clean exposed caliper piston surfaces before retracting the pistons. Ease piston retraction by opening the bleed nipple. Retract piston(s) with a suitable tool. Never lever against the disc friction face.
  • Thoroughly clean pad contact points in the caliper.
  • Check pistons, seals, boots and sliding elements on the caliper to ensure that they are free from damage and corrosion.
  • Always check the disc for minimum thickness and uneven wear when fitting new pads.
  • Never use clamps on brake hoses. Hoses contain multiple layers of braiding which give them their structural strength. The hose may become damaged or crushed, leading to hydraulic issues such as blockage or fluid leaks.
  • Never use mineral oil based lubricants on parts with rubber seals, this will cause the seals to swell.
  • Always fit a new pad fitting kit.