Originally Posted by JohnWinn
What's the advantage to using open-ended ball cups? Less slop?
To reduce ball cup stretch. You take off a link by undoing the ball stud rather than twisting the ball cup off the ball stud.
Everytime the ball cup is removed from the ball stud and put back on it stretches a little and gets loose over time making things more sloppy.
Some people ream out the top of an enclosed ball cup so hex drivers can be used to remove the ball stud.
There might be other reasons as well but that's the main one I can think of.