Truck bouncing

Toss the centermatics and balance the tires after a alingment for the entire tractor.

Its not right somewhere and frankly aggravating. Maybe the ride height is too low too high, shaft out of angle limits or whatever else. If that is a brand new front end and so on it should be like a mint new truck. But since you are not happy with it thats the only two things left I can think of.

At this point if the truck is still bad, sell it for another or dispose of it somehow.

 

Just a shot in the dark, try moving your 5th wheel one way or the other.

I've driven trucks that bounced one day and rode smooth the next depending on the type of load, how it's loaded, type of trailer, distance from tandem to tandem, distance between the stress cuts on concrete highways and the level of fuel in the tanks.

 

Second thought.
What shape are the springs in, sagged out, are they directional, biased on one end?

 

What brand of tires? Did you center rim to hub?

 

i have had an out of round new tires, in the past.

 

591's are ok tires. Look up Tru Balance alignment studs. Hub piloted wheels have a tendency to not mount square on the hub compaired to older stud piloted wheels. Look for difference in the gaps between rim and hub ears. Or take a lug nut of two off and see of the stud is centered in the whole. Probably not. This will fix most tire issues. I don't assemble anything without them. But you want the Tru Balance brand. It's a threaded sleeve, other brands only slide on. They have many options for your needs and Ron the owner will take time to talk you thru it. If you have access to a tire runout gauge, you can see that they are mounted to the hub out of center.