Systems and methods for reducing vibration in an electric motor using rotor bearing assemblies that are positioned within a bore of the stator to support the motor's shaft and rotor sections so that they can rotate within the stator bore. Each rotor bearing assembly includes an outer bearing and an inner bearing sleeve that rotates within the bearing. The bearing is secured so that its rotation within the stator is inhibited, but it can move axially. Each end of the bearing sleeve has a conically tapered contact surface which contacts and secures the corresponding rotor section and centers the rotor section with respect to the axis of rotation of the bearing. The contact surfaces of the rotor sections may be chamfered at an angle complementary to the tapered contact surface of the bearing sleeve to distribute the contact pressure between them over a greater contact surface area.