Raise the tires off the ground, put one hand at the top of the tire, and one at the bottom. wiggle the tire from those points, if it moves, your ball joints are bad, if it doesn't, no need to replace them yet.
This requires 2 people, 2 jackstands, a floor jack, and a 4 foot long 2x4 or pry bar.
Jack the car up and place the jackstands under the lower control arms as close to the ball joint as possible. Lower the jack so that the car's weight rests on the jackstands. Place the 2x4 or long pry bar under the bottom center of the front tire. Have you helper lift on the 2x4 or pry bar while you watch for movement or slack in the ball joint. If you see any movement, the ball joint is defective.
The ball joints are best removed and installed with a press. You can rent/borrow a suitable portable ball joint press from any of the major auto parts chain stores. You will also need a pickle fork type ball joint separator tool to disconnect the ball joint from the steering spindle.
Doing it without a press may require the removal of the lower control arm. Beware of the spring if you find that it is necessary!!! If it gets loose, it can kill or seriously injure people. The spring should be chained in place before attempting to remove the lower control arm. You will need a suitable spring compressor or other spring compression method to re-install the spring.
Sometimes when doing it by hand they won't move, I recommend once you have the tire off the ground, place a prybar under the tire and lift (you don't have give it alot of force). I replace them if there is more than 1/16" movement.
when driving and you hit a bump or a pot hole you ll hear a rattle like sound coming from the front end!and you can feel it in the steering wheel as well! my exploder is doing this as we speak! it needs a right upper and left lower! but with 2 feet of snow its kinda hard to do! and the garage has the stang in it along with 3 snowmobiles so I'm going to have my cousin do it at the shop! but this noise will almost always mean a ball joint! and if you let it go much longer than this you ll know its a ball joints when your front end drops down and causes a couple grand in damage!!!
Don't do what I did, wait till the left
front wheel fell off when my wife
was driving. It was on my local farm road
in the snow and she drove the car
1/2 mile to get to the driveway.
Only the steering was holding the
wheel on.
I tried to change the BJ myself
but could not do it with my air
tools. Had to tow it
to the local garage.
The way I heard to tell if BJ or any
other jount is bad is to grab the joint
with your bare hand and have someone
jostle the tire. You will easilly feel the
joint movement. It should not have
any movement.
At first glance, I thought someone was posting poems in 5.0 Tech...
Another thing I noticed when the ball joints on my '89 notch were going out was a pop that I'd get when turning the steering close to full-lock as I either pulled in or out of a driveway, especially if I was going over a curb at that time. My '86 does this, as well. When I changed the ball joints out on the notch, the popping went away completely.
Additionally, the car would try to lurch from one lane into the other, or would otherwise pull in either direction under moderate to hard braking. Replacing the brake pads, calipers, hoses, and flushing the fluid didn't change this, but replacing the ball joints made it go away, as well.
I have had 3 fox body stangs and all of them were bought with stock Ford ball joints in them (hence the missing grease fittings). When the ball joints went bad on all three cars, it would squeak really bad when turning or basically any suspension movement (dry ball joints and no way to grease them). Replaced the ball joints, and the noise went away.