* Warped Rotors: Heat is the enemy of brake rotors. Overheating, perhaps from hard braking, aggressive driving, or even prolonged downhill driving, can cause the rotors to warp slightly. This uneven surface causes the brake pads to grab unevenly, resulting in the pulsing sensation in the brake pedal. This is the most common cause.
* Other Possibilities (less likely, but should be considered):
* Worn or Damaged Brake Pads: Severely worn or unevenly worn brake pads can also contribute to pulsing. If the pads are very thin or damaged, the uneven contact with the rotor can cause pulsation.
* Sticking Caliper: A brake caliper that's sticking or not retracting properly can cause uneven pressure on the rotor, leading to pulsing.
* Contaminated Rotors: Grease, oil, or other contaminants on the rotor surface can interfere with braking and cause pulsation.
* Wheel Bearing Issues: While less likely to directly cause pulsing, a bad wheel bearing can create vibrations that might *feel* like brake pulsation. This is usually accompanied by other noises or play in the wheel.
* ABS Issues (less likely): While less common, a problem with the Anti-lock Braking System (ABS) could potentially contribute to pulsation, but this usually manifests differently (often with a pulsating pedal even at low speeds).
What to do:
1. Visually Inspect the Rotors: If you're comfortable working on your car, you can remove a wheel and visually inspect the rotors for warping. Look for discoloration (heat marks) and any obvious bends or uneven surfaces.
2. Check the Brake Pads: Inspect the brake pads for wear and damage. Uneven wear is a significant indicator of a problem.
3. Feel the Rotors: Carefully feel the surface of the rotors. If you feel any high or low spots, that indicates warping. Caution: Rotors are hot after driving; allow them to cool down completely before touching.
4. Professional Inspection: It's best to have a qualified mechanic inspect your brake system. They have the tools and expertise to diagnose the issue accurately and perform the necessary repairs safely.
In short: Warped rotors are the most likely culprit, but a thorough inspection is crucial to determine the exact cause of the pulsing brakes. Ignoring the problem can lead to further damage and potentially dangerous braking conditions.
