A hub for a vibration damper is formed by shell casting. The hub includes an outer annular surface or rubber diameter. In the casting of the part, the part line is formed along the center of this outer annular surface. The casting gate is also formed on the outer annular surface. The part line divides the outer annular surface into two halves. The surface of these two halves slope slightly away from the part line. When assembled, the elastomeric strip is located between the outer annular surface and inertia ring with edges of the elastomeric member extending up to edges of said casting gate. This, in combination with the different draft angles, maintains the elastomeric member in position during use.