Butterfly valves assemblies are provided that include a flowbody, a butterfly plate, an actuator and an upper chimney and a lower chimney disposed within the flowbody. The flowbody has an inner surface defining a channel. The butterfly plate is disposed in the channel, is rotationally mounted to the flowbody, and has an outer periphery. The actuator has an actuator output shaft that is coupled to the valve shaft via a serrated spline coupling. The upper chimney and the lower chimney are configured to include bearing assemblies that constrain radial loads and thrust loads exerted upon the valve shaft and minimize misalignment of the serrated spline coupling.