Worn rotors jeopardize vehicle brake system

Few things take as much abuse in a vehicle as the braking system. The effectiveness of your vehicle’s stopping power comes down to a few critical parts that need to be inspected regularly.

The high pitched squeal of old brake pads lets drivers know when they need replacing. But what about rotors, the metal discs that play a vital role in stopping your vehicle?

“The best way to deal with brake rotors is to have the vehicle regularly inspected by a qualified technician,” said Tony Molla, vice president of communications for the National Institute for Automotive Service Excellence. “You should do that two times a year, at a minimum, and before any driving vacation.”

Modern brake systems use palm-sized brake pads that press against disc-shaped rotors. The resulting friction stops the vehicle. 

“Rotors require careful inspection of a trained technician because even slight wear can warrant their replacement and precision tools such as micrometers are needed to measure that wear,” Molla said.

As a general rule, Molla said, brakes need to be inspected anytime they start making noise.

“If you hear grinding or metal-on-metal contact then you may need to replace the rotor,” he said.

In the past, rotors would be “resurfaced,” or sanded, to create a smooth surface for the brake pads. Yet, modern vehicles often require replacement rather than resurfacing.

“Rotors in many modern vehicles are thin and light-weight,” Molla said. “As a result, they have become a replacement part.”

Molla had the following recommendations:

  • How do you know when it’s time to have rotors replaced? Ask your service advisor to inspect rotors anytime you replace or rotate tires, replace brake pads or get an alignment.
  • Take your vehicle in for a rotor and brake inspection anytime the brake warning light is displayed on the vehicle dashboard.
  • Get an inspection immediately when you hear metal-on-metal or grinding noises. It could be an indication that rotors need replacing. Ignoring this warning sign could cause your brake system to fail.
  • Use only a certified technician to inspect the brake system. Brake systems in most modern vehicles are designed to replace rather than resurface rotors.
  • Inspect rotors and brake systems at least twice per year at the minimum.

“Never delay in having your brake system inspected or repaired,” Molla said. “Brake systems can fail quickly when you are on vacation, especially if you are traveling mountain roads.”