Why Is My Car Vibrating When I Brake?
There are many different reasons why your car may vibrate or shake. One of the more common reasons, especially if you feel the vibration while braking, is a warped brake rotor. When applying the brake pedal, the brake pad pushes against the brake rotor. The friction is what causes the vehicle to stop. The rotor and pad must make even contact. Even the slightest abnormality can cause a serious reduction in how long it takes to come to a full stop.
Uneven wear patterns or a warp of the rotor can cause a vibration or shaking when stopping. Often you'll feel the vibration in the steering wheel or at the brake pedal.
You may ask, how does a rotor warp? There is so much heat and friction in the braking system. Overtime with constant heat and pressure as the rotor thins it can lose shape.
If new brake pads seat against a worn rotor the surfaces will not align and you can feel a vibration or shutter. Best practice is when replacing brake pads either resurface or replace rotors.