A threshing system including a rotor cage with a plurality of slots therein, a first bank of vanes and a second bank of vanes arranged within the cage. An adjustable vane control system is coupled to the rotor cage and the banks of vanes. a first and second member are respectively pivotally coupled the vanes in the first bank and the vanes of the second bank through corresponding slots. Linkages couple an arm to the members. The first and second members each having a range of travel defined by the slots. The members each having a surface facing the outer surface of the rotor cage, the surfaces of the first member and the second member each remain tangent to the outer surface of the rotor cage as the first member and the second member are moved within their range of travel.