In a swing-axle system the wheels are connected to halfshafts which are jointed only at their inner ends. This means that as the suspension rises and falls and the driveshaft angle changes, the wheels go through a considerable camber change. This can result in a loss of grip.
An unpleasant handling trait called jacking can occur with swing-axle rear suspension if weight is transferred to the front of the car in the middle of a corner, for example if the driver suddenly lifts off or brakes. As weight transfers off the rear wheels and the car pitches forward, the rear wheels droop and assume a positive camber which reduces rear grip. In extreme cases the rear of the car tries to 'climb' over the outside rear wheel and driveshaft, leading to sudden oversteer.