What could cause brakes to grab?

Answer 1

The two main reasons for this is a sticky, or malfunctioning brake caliper on disc brakes, or piston on rear drum brakes. on the front disc brakes you can tell if your caliper is not releasing by driving slowly on a straight and level road, then let go of steering wheel and apply brakes (only go about 15 MPH). if it pulls suddenly to one side, chances are that caliper is sticking closed and upon inspection of that wheel , you will notice a less thickness of brake padding than the other side. Another reason is that the pads are down to the metal, and when you apply brakes, you have metal (from the worn pads) on metal (from the rotors). you should have been hearing a loud squealing noise prior to this. now you must change pads, and rotors. Or in rear, shoes and drum. Rotors or drums are most likely to have deep groves in them, sometimes you can just get them machined cut, less expensive.