How to Check for Brake Rotor Runout

Brake rotors are made of cast iron and are subject to runout. When the car is engaged, the brake pad is pressed against the rotor. The heat and friction that occurs during this process is absorbed by the rotor. Heat is caused by friction and can cause your rotor to wear out over time. The performance of the rotor is directly related to the performance of the brakes. Here are a few simple steps you can take to check your rotor for runout.

Tools and Materials

  • Breaker bar
  • Socket set
  • Jack
  • Pliers
  • Dial indicator

Step 1 – Remove the Tire

Using the breaker bar, loosen the lug nuts. Next, use the jack to move the vehicle off the ground and remove lugs and tire. You will also need to remove the brake components to get to the face of the rotor to measure runout. Once they are off, set these aside the same way they came off so that you can keep things organized.

Step 2 – Check for Runout

Set the dial indicator on its stand and position it on the rotor for a reading. Make sure the gauge is at “0.” Turn the rotor and the dial indicator will measure runout. If the measurement fluctuates any more than 4/1000th (0.004) of an inch, you should replace the rotors.