The ball joint on the Toyota Corolla works with the car's steering and suspension, much like the ball-and-socket joint in a person's hip. The ball joint can wear down over time and cause the car to shimmy or make the steering erratic. The joint must be as securely fastened to the steering knuckle and control arm as possible. If you ever remove a ball joint from the Corolla, keep this in mind when you reinstall it, whether it's the same ball joint or a replacement.
Raise the car with a normal jack and then support it on jack stands; even if you're only working on one wheel, it helps to raise the whole car or at least the full front end. It also helps to loosen the lug nuts on the wheel you'll be removing before you raise the car so the wheel will be easier to remove.
Remove the cotter pin from the ball joint stud, then loosen the stud's nut; do not remove the nut yet. There is not much clearance between the ball joint stud and the CV joint; you'll likely need an open-ended wrench. To separate the ball joint from the steering knuckle, use a ball joint separator tool that resembles a picklefork. Once the ball joint is separated, continue to remove the stud nut. You need to back off of the nut after a turn or two, pull down on the stud and give the nut another turn or two until the nut is completely off. Remove the nuts and bolt securing the ball joint to the control arm and then use a pry bar to separate the ball joint from the control arm.
