Q: Sometimes when I brake lightly the car jerks and stops very abruptly. This happens especially after shifting to drive from park.

The brakes should apply smoothly and consistently is response to intensity of pressure on the pedal. If the brakes grab or apply in "step" fashion, that is not normal. The abrupt operation that you are describing could be caused by contamination of the brake pads, loose parts, a fault in the proportioning valve (which distributes brake system pressure from front to rear) or other causes. If you desire an inspection of this issue, and the required repairs, please use YourMechanic’s brake safety inspection service page to request mobile service right to your door. If you have further questions or concerns, do not hesitate to re-contact YourMechanic because we want you to make the most of your repair dollars and help you to get the best possible results.