Ball joint taper

[GSXRJJordan]

Originally Posted by anotherblusi

A few things come to mind. With motion, you would want it localized at the ball joint only. This means that the spindle must not be allowed to move on the ball joint bolt. With a straight design, the spindle and ball joint would need to be pressed together, and would require a bearing separator of sorts.

A taper design would increase contact surface area, not require a press for installation, and doesn't necessarily need a special tool for removal.

The taper design would also resist higher shear loads than a straight design.

A castle nut/cotter pin on the bolt that's fit correctly (torqued) will hold just as well in my opinion. By industrial standards, the weight of a car (even under 3g or 4g load) is not anywhere near the tensile strength of decent hardware. I believe this is why all aftermarket control arms come with heims/bolts, instead of standard tapered ball joints.

Thinking of sheer force, it's true that a taper would be superior, but I can't think of any time (except for a collision with a curb/etc) where you'd see loads like that. And again, it'd have to be 4g's or so before you'd come close to maxing the heim, and a bunch more before you snapped a 10.9 M12 or M14 bolt.