There are a number of signs that could indicate rotors that need to be replaced.
• Sluggish stopping or poor brake response. If you notice that the brake pedal is going down farther than normal when depressing the brakes, this could be an indication that the brake pads or rotors are worn down and need to be replaced. This could however, also be an indication that the brake fluid level is low.
• Shaking or rattling when depressing the brakes. When you press the brake pedal down, if the rotors are warped or worn, this could cause “chattering” from the wheelbase. This is created when the brake pads calipers squeeze the rotor, And the rotors get warped as they force the pads out as they are trying to squeeze in. The faster you are moving, the more violent shaking and chattering will be. This can cause a driver to lose control and can increase the stopping distance.
• If you hear a grinding noise while braking, this could be a sign that the brake pads are worn down to the metal and can also be an indication that the rotors are worn out.