There are possibly serious situations indicated when brakes make noise, vibrate, or feel soft. Address these symptoms promptly to improve safety and save time & money in the long run.
The first step in silencing noisy brakes is to do a complete inspection of the braking system to identify the source of the problem. Look for excessively thin brake shoes, scored or warped rotors and drums, brake fluid leaks and oil or grease on pads and shoes. Make sure pads and shoes have not worn down to the metal backing plate.
Brake Squealing and Groaning
Brake squealing often indicates the pads are worn down, and those squeaking wear indicators are doing their job. When the abrasive pressure of many traditional brake pads against the rotor causes squealing, or if you have low quality rotors, the resulting noise is more annoying than anything else.
Other reasons for squeals and squawks are warped or glazed brake rotors, mis-aligned or loose calipers, loose wheel bearings, or sticky pistons. If you hear clunking, metal-to-metal screeches or the brake pedal vibrates, you should check out the braking system immediately. The braking system is the most critical system on any vehicle.
Groaning noises also can be caused by low quality or abrasive brake pads. Squealing and groaning can both be minimized by installing premium brake components. Use the same type of pad fitted as original equipment (OEM) or use an upgrade pad, such as the ultra-premium ceramic pads.
Another solution is to coat the back of the brake pads with an anti-squeal compound, a thick heat-resistant polymer adhesive applied to the back of the pad, which provides a cushion between the pad and piston and helpd the pad retract with the piston. This material is available as an aerosol spray or as a liquid. Coat only the area that contacts the piston, avoiding the front contact area of the pad or rotor (which would be like waxing your brakes).
If the brakes make squealing noises soon after a brake job, return to the shop where the work was done as soon as possible, and have the brakes checked out by a technician. Installing premium brakes, calipers and rotors may cost a bit more up front, but often provides noise- and vibration-free operation and longer pad life.
Pulling and vibration
When your brakes are applied and the vehicle pulls to one side, check for either low tire pressure or a sticking brake caliper, with maybe a leak or some corrosion-caused stickiness. Any uneven brake pad and rotor wear will reduce the life of the pads and causing steering wheel vibration (or "judder").
The rotor can be machined smooth, but in the long-term the corroded caliper or rotor may need to be replaced. Let a trained technician assess the situation and fix it appropriately the first time.
One solution is installing vibration dampers, made of a self-stick fiber material for the back of the brake pad backing plate. Some damper designs are have a mushroom shaped button spring in the center that fits snuggly into the piston head, which also helps pull the pad away from the rotor as the piston retracts to stop the braking action. This increases the clearance between pad and piston and eliminates vibration and squeal.
When your pedals react softly, often this is due to air or water in the brake system, typically caused by improper bleeding and general corrosion. Air in the system (being less dense) forces you to push harder on the brake pedal than normal to stop. Water can impact caliper performance by causing brake fluid to boil prematurely, result in a drop in stopping power. Drain and replace the brake fluid as recommended.