Brake noise can be one of the first signs that something is wrong with the braking system. Delphi Technologies provides a guide to brake noise, its causes and how you can resolve it.
Sound is vibration and these vibrations set the air around them in motion creating a sound wave. The pitch of the noise is determined by the speed of the vibration. The same rules apply when it comes to brake noise. All braking components vibrate to some extent, creating noise. For the most part, this noise is not detectable by the human ear but when this vibration increases in intensity, or induces a secondary vibration in another part, the brake disc acts like a speaker, amplifying the noise and making the vibration audible.
Brake noise can be caused by a variety of component or installation issues, including: excessive corrosion, seized or bent location pins, partially seized calipers, built up dirt and brake dust, excessive runout, Disc Thickness Variation (DTV) and worn brake discs. All of these can cause vibration between the disc and the brake pad, creating noise. Whilst the braking system is the most common cause, noise can also be created when the motion in braking creates movement in another part, typically steering components and motor/transmission mounts.
Delphi suggests carefully checking the entire brake system during a service, especially the pads, as they can provide a good indication of the system’s condition. Examples of this could be tapered wear on the pads, suggesting a faulty caliper or a damaged back plate, which could be the result of excessive force during installation.
In recent years, demands for higher performance and reduced weight in modern vehicles have led to material changes, resulting in increased use of supplementary processes to counteract vibrations. One of the most effective ways to help prevent brake noise however, is to only use OE-quality brake pads, as poor standard pads are one of the biggest contributors to noise.
Unlike other replacement parts manufacturers, every Delphi brake pad incorporates an OE underlayer technology. The 3mm layer of modified noise-absorbing friction material significantly reduces noise, as well as acting as a thermal insulator and ensuring a stronger pad. Delphi Technologies offer two technical training courses on the fundamentals of braking. The first is a one-day course aimed at technicians who want to focus on modern braking systems repair and servicing – gaining insight into the operation of systems and legal requirements. The second training programme is also a one-day course looking at the in-depth systems used in automated braking and the diagnosis of braking systems.
For more information on Delphi’s training offering, call: 02038 161 400.
BEST PRACTICE ADVICE TO MINIMISE THE POTENTIAL FOR BRAKE NOISE
- Ensure that all corrosion, built up dirt and brake dust is removed from the caliper.
- 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 and lightly smear with brake grease.
- Check pistons, seals, boots and sliding elements on the caliper to ensure they are free from damage and corrosion and able to slide.
- Replace all anti-rattle clips, springs and pins, which can lose their spring tempering due to the high brake heat.
- Always check the disc for minimum thickness, DTV and runout when fitting new pads.
- Always check that the correct pads are used and they’re positioned correctly in the caliper. They should fit freely in the brackets to avoid ongoing contact with the discs.
- 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.