Locking Jaw to tight??.... Excessive Bounce with weight

Take a look at your suspension.

The 5th wheel's ability to prevent a trailer from slamming back and forth in it's kingpin is separate from overall bouncing.

You could also be nose heavy in that trailer which will beat on your drives more but should not be a problem to the tractor as long you are under 34000 on your drives.

 

Time for shocks or the suspension isn't pumping up for the load.

My truck gets real bouncy if either truck or trailer are deflated.

 

Check for worn shocks and proper airbag height.

 

Are you pulling the same trailer?
If so get the king pin checked. It could be worn or damaged.

 

Replace the pivot bushings on the fifth wheel. The ones where the plate swivels and mounts to the base. On my truck they are only rubber. Get the new poly ones.
I think they were under $70.
Holland 5Th Wheel Bushing Poly Kit Rl04413 • $57.99

 

Any Shop worth it's salt will have a tool that is a "go/no go" measuring device to check whether the hole in the fifth wheel has wallowed out and become too large. It happens over time, especially if it's hooked and unhooked often. It's not an expensive procedure to get it checked. If it's wallowed out the only fix is to replace it with a new or used one, which is pricey but it's a safety issue that can't be ignored for long because as the hole gets bigger ( wallows ) it accelerates the growth of the problem. Get it checked soon, then you can plan accordingly.

 

If he had a wallowed out hole. He'd have some kinpin slop like what mine does. I get a thump when I take off from kingpin movement. Using that lucas 5th wheel slide grease eliminates that. Pretty much every local job I've pulled a 5th wheel trailer has been that way.

 

A lot of times that thump you feel taking off and stopping is slack in the drive line. Be it from the hole in yoke that u joint cup goes in being egged to the splines on jack shaft wore out or even slack in one differential. That's why it's best to use a new blank pin with a handle welded on it to set the jaws in 5th wheel and check for slack. Then you know what you have. A binding 5th wheel can cause all kind of crazy problems be it dry or the jaws too tight.