If it only works 90% of the time you need a bigger hammer.
I'm a disciple of the Bigger Hammer. However, when I pulled apart the driver's side on WCJr it wouldn't budge with me hitting it full force with my biggest hammers. I ended up pulling the spindle with the control arms. The top ball joint came loose and I chucked the spindle and lower arm into my vise and used my air hammer to pop the ball joint out.I've tried the hammer trick, and it never works for me.