* Caliper Piston(s): This is the most common cause. If the caliper piston(s) are sticking or seizing, they won't fully retract, keeping the pads slightly in contact with the rotor, even when you're not braking. This leads to a grinding noise. The pistons might be corroded or dirty. You'll need to inspect and potentially lubricate or rebuild/replace the calipers.
* Caliper Slide Pins: These pins allow the caliper to move freely. If they're seized or rusty, the caliper can't move correctly, again causing constant pad-to-rotor contact. Clean, lubricate, or replace these pins.
* Parking Brake: Is your parking brake fully released? A partially engaged parking brake will cause grinding. Make sure it's completely disengaged. Inspect the parking brake mechanism for issues.
* Contamination: Did you get any brake dust or other debris on the rotor surfaces during the replacement process? This could be a source of grinding. Thoroughly clean the rotors before installing new pads.
* Rotor Warping/Damage: Although you replaced the rotors, it's possible a flaw went unnoticed during inspection or that damage occurred during installation. Ensure the new rotors are correctly seated and aren't warped.
* Incorrect Pad Installation: While less likely if you followed instructions, improperly installed brake pads (not seated correctly, etc.) can cause grinding. Double-check your work against the repair manual or a reputable online guide specific to your car.
* Something else in the brake system: In rare cases, there could be foreign objects within the brake caliper, or problems with the brake lines themselves. This is less probable if the brake system was working fine prior to the repair.
Troubleshooting Steps:
1. Safety First: Always use safety glasses and gloves when working on brakes. Make sure the car is parked securely on a level surface, and the emergency brake is engaged.
2. Visually Inspect: Carefully examine the calipers, slide pins, and rotors for any signs of rust, corrosion, sticking, or damage. Try to spin the rotors by hand – they should spin freely without resistance.
3. Check Parking Brake: Make absolutely sure your parking brake is fully disengaged.
4. Test with Jack and Wheel Removed: Carefully jack up the vehicle, remove the wheel, and try spinning the rotor. Does it spin freely or does it still grind? This will help isolate the problem to the caliper, rotor or something else.
5. Lubrication: If you find corrosion or sticking, carefully clean the calipers and slide pins, and lubricate them with brake caliper grease (never use general-purpose grease).
6. Caliper Rebuild/Replacement: If cleaning and lubrication don't solve the problem, you might need to rebuild or replace the calipers.
If you're uncomfortable performing these tasks, it's best to take your vehicle to a qualified mechanic. Brake problems can be serious, and it's crucial to have them repaired correctly to ensure your safety.
