Abstract: A plastic cylindrical camstack has different inside diameters. This leads to the problems of maintaining concentricity and elimination of excessive warpage during molding of the plastic. These problems have been substantially overcome by removing selected portions of the camstack in the area where the inside diameter is smaller, so that the net thickness of unbroken hub wall in this area is equal to the thickness of the hub wall in the areas where the diameter is larger. The material is removed to form serrations in the hub exterior surface, the serrations having a width slightly smaller than the length of a hub follower which rides on the hub surface.