Next, we slid a floor jack under the lower A-arm and slowly raised it to add a bit of compression to the spring. Another couple of raps from the hammer on the upper and lower ball joints will break them loose. With the spring compressed we safely removed both castle nuts from the upper and lower ball joints. Then we slowly lowered the floor jack. As the lower A-arm comes down, the tension on the spring is released at a controlled rate and won't surprise you like a jack-in-the-box.