A damper includes a housing, a cover, a rotor and a valve relatively rotatable with respect to the rotor. When rotated in one direction, a space between the valve and the rotor is opened to increase damper fluid flow and reduce damper resistance. When rotated in an opposite direction, the space between the valve and the rotor is closed to decrease damper fluid flow and increase damper resistance. A shaped flange on the rotor provides a changing space between the rotor and ribs in the housing when the rotor is rotated. The cover is self-centering on the housing.