10.With a jack under the lower A-arm, the spring tension is not pushing ball joints in the A-arms. This will relieve the pressure so the upper control arm and knuckle can be removed. The upper A-arm is held in place by a link that is threaded on each end and holes drilled through it. This is called the cross-shaft. With the ball joint free from the knuckle and the cross-shaft nuts unbolted, the upper control arm comes right off.