Good for tapers into steel or cast iron forgings/housings where access is reasonable. Not suitable for use on aluminium castings or delicate vehicles!
Step 1: Splitting/breaking the Taper
These balljoints have a taper that fits into a matching taper on the suspension part, and is held in place with a nut. The nut is only there to put tension on the taper - the taper is the part of the joint that carries all the load.
When you remove the nut, usually the joint will just sit there, stuck. There are several ways to 'break' the taper joint.
One - use a balljoint removal tool. These look like forked G-clamps, which try to press the taper out. They can work, but usually work best in combination with (three) or (four)
Two - use wedges driven into the gap between the two components. This can work, but destroys the joint, the rubber boot, often damages the parts, and the wedges can 'shoot' back out of the joint if it is at all springy and do a convincing job spearing you to the wall through your eyesocket. (I don't like wedges...)
Three - try to hammer the joint out by hammering on the end of the thread where the nut was. This is ok, but typically damages the thread (tip - screw the nut back on until it is flush with the end of the thread to protect it) and isn't very effective.
Four - the method shown - hammer either side of the taper at a slight angle. This squeezes the bottom of the housing that the taper fits into, and opens up the top. A few sharp blows and the taper pops out without damaging anything. Be brutal and smack the parts as hard as you can given the space available - you won't break things.
Do make sure that both hammers strike at the same time - else you will not squeeze the housing, the joint will not loosen and the force from teh blows will go elsewhere (the upper wishbone in this innstance). The loads are nothign comapred to hitting a pothole so will be fine, but you'll be wasiting your energy!
For *really* stubbourn joints use (one) and (four) together - (one) to apply pressure and (four) to shock the joint free.
I prefer 24 oz ball-pein hammers for this job - nice to handle. Avoid claw/carpenter style hammers, as it is easy to damage other parts with the end you aren't using. 4lb club hammers are great if you can get a good swing in, but I find them a little unweildy.
At the end of the video you can see the joint pop up and out of the housing slightly - as soon as the taper is broken the joitn will slide out by hand.
A few taps, no special tools, and the joint can still be re-used afterwards!