YOU’RE IN CONTROL OF BRAKE NOISE

WHAT IS BRAKE NOISE?

Brake noise typically originates from vibration on a part within the wheel end section of the vehicle – between the tyre and the connection to the chassis. Noise is often blamed on the brake pad itself, but can come from any part, from the wheel bearing to the ball joint. Within the brake system, it’s normal to have some vibration, but it is not usually intense enough to be audible.

TYPES OF NOISE EXPERIENCED BY DRIVERS

LOW FREQUENCY VIBRATIONS – JUDDER

DESCRIPTION

A deep noise with frequency below 300 Hz.

CAUSES

• Poor tolerance
  (poor fitment on the hub or excessive disc thickness variation).
• Disc damage

SOLUTION

Replace the disc and clean and lubricate all surfaces of the brake assembly according to the vehicle manufacturer’s instruc

MEDIUM FREQUENCY VIBRATIONS – SQUEAL

DESCRIPTION

Noise with frequency in the range 300 - 5.000 Hz.

CAUSES

• Sticky movement on the caliper piston,
• non-planarity of the working surface of the disc,
• pad fitting errors,
• incorrect allocation of anti-noise fixings (eg. shims),
• disc thickness too low.

SOLUTION

• Clean and lubricate components of the caliper,
• ensure disc planarity (once fitted on to the hub) will stay within a tolerance of 0.1 mm.
• Clean the hub surface, machine disc surface,
• replace disc and make sure brake pads,
• shims and accessories are fitted properly.
• Consider damping noise intensity with shims or brake pads with noise-reduction features.

HIGH FREQUENCY VIBRATIONS – SQUEAK

DESCRIPTION

Noise with frequency higher than 5 kHz

CAUSES

The most common reason for a squeak is a molecular vibration within the friction material during application to the brake disc.

SOLUTION

Replace the brake pad set. Also check that the accessories (e.g. the caliper clips) are correct and properly fitted

VERY HIGH FREQUENCY VIBRATIONS – ULTRASOUND

DESCRIPTION

Noise with frequency higher than 12 KHz, greater than the upper limit of human hearing.

By ferodo