Most brake problems announce themselves before they get expensive. Knowing the sound is the difference between a $300 brake job and a $1,500 brake-and-rotor job. Here is what each sound usually means, how urgent it is, and whether you can drive to the shop.
High-pitched squeal at low speed.
Usually the wear indicator (a small metal tab built into your brake pad) scraping the rotor on purpose to tell you the pads are at end of life. Not urgent yet. You have a few hundred miles before the pad runs out. Schedule a brake job in the next two weeks.
Loud grinding when braking.
The pad has worn through and metal is now hitting metal (rotor against caliper bracket or backing plate). Urgent. Every stop you make from this point gouges the rotor deeper, which turns a pad job into a pad-and-rotor job. Drive directly to a shop. Avoid heavy braking.
Pulsation through the pedal when stopping.
Warped rotors, almost always. The rotor surface has minor high spots that the pad is hitting unevenly. You can drive on it, but you will not pass a pre-purchase inspection and your brake performance is degraded. Either resurface the rotors (if there is enough material left) or replace.
Scraping noise that does not change with brake pressure.
Often a backing plate (the thin metal shield behind the rotor) bent inward and rubbing the rotor. Common after potholes. Cheap fix; we bend it back at no charge if you are already in for service. Not urgent. Drivable.
Single thunk when first applying brakes.
Loose caliper bracket or worn slide pins. Caliper is shifting before it grips. Get this looked at within a week. Easy fix; ignored, it leads to uneven pad wear and sometimes a stuck caliper.
Squeak only in cold or wet weather.
Surface rust on the rotor face from sitting overnight. Goes away after the first few stops once the rust is brushed off. Not a problem.
Brake pedal slowly sinking to the floor.
Internal master cylinder leak. Urgent. Park the car. Tow it in. Driving on a sinking pedal will eventually leave you with no brakes at all.
What we do when you bring it in.
Pull all four wheels, measure the pads and rotors, inspect the calipers, check the brake fluid moisture content, look at the lines and the master cylinder. Written estimate before any work starts. Full brake-repair service details or call (415) 648-2226.