Why does my 3-car wedge wobble like its going to shear off the 2 5/16" ball?

This oughta be good...

A 3 car trailer hooked to a ball hitch

 

Not any different than our 44' gooseneck flat hauling 22k. It works for our application where a fifth wheel would not. But I also upgraded to a 33,000 pound ball.

Sorry, I can not help with the wobble.

 

I would check to see if you could have a bent rim or axle. The only other thing that I can think of is if you tend to move your steering wheel back and forth a lot. Have you noticed any excessive wear on your tires?

 

Maybe it just seems that way because you're not used to carrying weight that high... and/or 3 cars with ~half tanks of gas are surging... and/or you're not securing the suspensions down good and tight...and/or as G/MAN suggests you're used to "sawing" the steering wheel.

Is that the right size ball? Cracked frame? Bent rim? Mis-mounted wheel? Loose/misaligned axle/s? Did you buy this rig new or used?

 

When drivers pull a trailer that is top heavy, such as with cars, you will get some sway. There is a tendency to compensate for the sway by moving your steering wheel to compensate. That can make the sway much worse. It takes a steady hand on the wheel to keep this from happening. You might watch your behavior when you have a load on the truck to see what you are doing and whether you might be moving the steering wheel from side to side. If that is what is happening then it is an easy fix. Just make sure to keep your steering wheel steady and the problem may be solved.

 

As long as you understand a cracked frame can be difficult to ~impossible to detect. Someone sold a presumably perfectly good trailer for some reason.

I'd pull one side then the other up on a curb (or something) to put it in flex and or go over every inch of that frame with a good source of light... after I ensured all the tires were of identical/correct size.