First off, the terminology I will use. Some of these parts have different names, depending on who you ask or where you go. I’ll try to be as generic as possible.
Ball Joint – a ball and stud joint that usually has a wide range of motion. Usually used to connect control arms to steering knuckles
Control Arm – hinged link that connects the hub or knuckle to the chassis. (Some parts have other names but also fall under the control arm definition)
Tie Rod – a ball and socket joint like a ball joint, co nnects the steering gearbox or rack and pinion to the steering knuckle for directional control.
Bushing – rubber, polyurethane or metal that is the interface between a control arm and the chassis – allows for flex and rotation
In the above picture, we have in blue the lower control arm, some refer to as LCA #1. In Red, another lower control arm, LCA #2, also known as a caster arm or radius arm. Orange is the lower ball joint, green is the upper control arm with integral ball joint, and in purple, the steering knuckle. If they were pictured, the outer tie rod end attaches to the lower ball joint.
How to check it all. All we need to check this stuff is a pry bar or similar substitute about 2-3′ long and a jack. A friend to help is nice but not required, but most importantly, we’re going to need some common sense.
Ball Joints: With the car flat on the ground, place a jack underneath the forward lower control arm, LCA 1. Raise the jack until the tire is approximately 3-4″ off of the ground. Now, using your pry bar, situate it underneath the tire and try to pry the wheel and tire straight up. Here is where having a friend helps. You need to see if there is any up or down movement in the lower ball joint as you are prying up. Any movement at all calls for immediate replacement. You can visually see movement, or, I like to put my hand on the joint to feel for movement. While we have it jacked up this way, grab the wheel and tire at the 12 and 6 o’clock positions and shake it back and forth. Look and feel for movement in the upper and lower ball joints. Same goes here as earlier, any movement, replace it now.
Tie Rod Ends: With the car jacked up as before, or from the frame, either way, grab the tire and wheel at 3 and 9 and rock it back and forth. Feel the inner and outer tie rod ends for a light clunk. An extremely small amount of play is acceptable, but if in doubt, change it out. Movement here, any at all, will cause the vehicle to be out of alignment. Even if the alignment machine says it is aligned, as soon as you drive the vehicle, the numbers mean nothing.
Control Arm Bushings: The forward lower control arm is pretty reliable, but shake the wheel/tire at 12 and 6 with the car jacked up from the chassis (not the control arm as before) and look for movement. The rear lower control arm is more difficult to test and you should just be looking for visually worn or torn bushings. These are a common failure though they will never come apart completely, they just cause dynamic toe changes as you drive which causes an otherwise good alignment to exhibit bad tire wear. Upper bushings, look for movement the same was as you did the forward lower control arm.
Here’s an example of a lower ball joint on an 1IS/2GS front suspension. The two holes on either side of the ball stud are where it mounts to the steering knuckle, the hole far left is for the tie rod end.