The present invention provides a vehicle including a frame, a rear wheel, a swingarm coupling the rear wheel to the frame, and a pivot shaft assembly rotatably coupling the swingarm to the frame. The pivot shaft assembly includes a first shaft having a non-circular outer surface engageable with a corresponding non-circular aperture in the frame. The pivot shaft assembly also includes a second shaft threaded to one end of the first shaft. The second shaft pivotably supports one side of the swingarm with respect to the frame. The pivot shaft assembly further includes a third shaft threaded to the other end of the first shaft. The third shaft pivotably supports the other side of the swingarm with respect to the frame.