A rotor assembly of an electric machine includes a rotor body and a shaft assembly positioned at a central axis of the rotor assembly, and operably connected thereto. The shaft assembly includes a main rotor shaft operably connected to the rotor body, a center drive shaft located inside of the main rotor shaft, and a hydraulic damper sleeve located radially between the main rotor shaft and the center drive shaft. The hydraulic damper sleeve defines a plurality of cavities between the hydraulic damper sleeve and the center drive shaft. The hydraulic damper sleeve is configured to urge a fluid into and out of the plurality of cavities thereby damping relative circumferential motion between the main rotor shaft and the center drive shaft. A plurality of flow restrictors are configured to easily allow fluid into the plurality of cavities, while restricting flow of fluid out of the plurality of cavities.