Q: Rear Brake Imbalance

The brakes front and rear would need to be inspected for any excessive wear on the pads and rotors. The rear calipers may be sticking due to the caliper slides may make only one side of the rotor work. Have the rear pads and rotors checked to see if the brakes engage when the brakes are applied. You most likely have binding rear calipers and need to replace both rear calipers. These type calipers have a built in parking brake mechanism that may be seized causing the caliper to not keep tension on the pads and the pads will travel too far before engaging the rotors. A complete brake safety inspection should be done to see if one or both calipers and rotors with new pads should be replaced.