* Warped Brake Rotors: This is the most common cause. When brake rotors warp, they become uneven, causing vibrations that transmit through the steering wheel and into the car body when the brakes are engaged. The heat generated during braking can exacerbate this.
* Worn Brake Pads: Severely unevenly worn brake pads can also cause pulsating or shaking during braking. One pad wearing faster than others creates an imbalance.
* Faulty Caliper(s): A sticking or seized brake caliper can cause uneven braking force, leading to vibrations. This is often accompanied by other symptoms like uneven brake pad wear or a dragging brake.
* Wheel Bearings: While less likely to cause shaking *only* during braking, worn wheel bearings can contribute to vibrations that become more noticeable under braking load.
* Driveshaft/Axle Issues: A problem with the driveshaft or axle could cause vibrations transmitted to the chassis that are amplified during braking. This is less common but possible.
* Out-of-Balance Tires or Wheels: Though usually noticeable during driving regardless of braking, significantly unbalanced tires or wheels could be causing or contributing to the problem, especially if the imbalance is only pronounced under braking load.
* Tire wear: Uneven tire wear can also contribute to vibrations under braking.
Troubleshooting Steps:
1. Visually inspect the brake rotors and pads: Look for scoring, warping, uneven wear, or excessive corrosion. This can often be done yourself without specialized tools.
2. Check the brake calipers: Look for signs of sticking or leakage. Try to gently push and pull on the caliper pistons. A sticky caliper will be difficult to move.
3. Check wheel bearings: Look for play in the wheels. A professional mechanic can typically test wheel bearings quickly and easily.
4. Get your tires balanced and rotated: A professional should be able to quickly perform a wheel balance, and rotating tires can often help determine if unequal tire wear is at play.
Important Note: If you're not comfortable working on your car's brakes yourself, it's best to take it to a qualified mechanic. Brake problems can be serious and potentially dangerous. A professional will have the proper tools and expertise to diagnose the issue accurately and safely repair it.
