Rotor/Drum Imbalance

Rotor/Drum Imbalance

Rotors and drums do not have a set tolerance. However, rotors or drums with more than 21 g (0.75 ounce) imbalance have the potential to cause vibration. Inspect the rotors and the drums for imbalance using either the on-vehicle or the off-vehicle method.


Checking Rotor Imbalance (On-Vehicle)

1. Support the vehicle rear axle on a suitable hoist. Refer to Lifting and Jacking the Vehicle (Service and Repair) in General Information.
2. Remove the rear tire and wheel assemblies. Refer to Tire and Wheel Removal and Installation.
Caution: Refer to Work Stall Test Caution in Cautions and Notices.
3. Reinstall the wheel nuts in order to retain the rotors.
4. Run the vehicle at the complaint speed while inspecting for the vibration.
5. If the vibration still exists, perform the following steps:

1. Remove the rotors. Refer to Front Brake Rotor Replacement and Rear Brake Rotor Replacement.
2. Run the vehicle back to speed.

6. If the vibration is eliminated, perform the following steps:

1. Remove the rotors one at a time.
2. Perform the vibration test for each rotor.
3. Replace the rotor that is causing the imbalance.
4. Inspect the balance of the new rotor.




Checking Rotor Imbalance (Off-Vehicle)

1. Measure the diameter and the width of the rotor.
2. Mount the rotor on a balancer in the same manner as a wheel.

Important: You can only inspect the rotors for static imbalance. Ignore the dynamic imbalance reading.


3. Inspect for static imbalance.
4. If the rotor shows imbalance, replace the rotor.
5. Inspect the balance of the new rotor before you install the rotor on the vehicle.