Brakes that grab - biting harder than expected for the pedal pressure, or catching abruptly - make the car hard to stop smoothly and can be unsafe. Several faults cause grabby brakes. Here is what to look for.
Contaminated pads or rotors
Oil, grease, or brake fluid on a pad or rotor makes the brake grab unevenly - the contaminated spot bites differently. A leaking caliper that soaks a pad is a common cause. Contaminated pads usually must be replaced, and the rotor cleaned or replaced.
A sticking caliper
A caliper that does not release smoothly can make one wheel grab; see sticking caliper symptoms. This often comes with a pull to that side and a hot wheel. Freeing or replacing the caliper restores smooth braking.
Glazed pads or a bad surface
Glazed pads can grab-and-slip, and an uneven rotor surface causes a grabbing pulse; see glazed brake pads. Improperly bedded new pads can also feel grabby until they settle. Cheap pads sometimes bite inconsistently by nature.
An over-sensitive booster
A fault in the brake booster or its valve can over-assist, making the pedal hyper-sensitive so light pressure grabs hard - see why brakes lock up. Diagnose the cause - pads, caliper, surface, or booster - and fix it. Fit quality pads and fresh hardware, bedded in properly.