How to fix trailer bucking?

Are the overload/helper springs on the truck rear axle making contact with the perches? There was a certain point my dually would get rough. If the overloads were very close to the perches but not touching, every bump in the pavement would cause the overload springs to make contact giving a jarring ride. Once loaded & the overload springs were fully engaged the ride would smooth out considerably..

They make extensions for the perch to engage the overload/helper spring sooner so they'd be working while lightly loaded & keep you from bouncing off them.

Seen some guys remove the overload springs, & add the air assist so there is no chance of bumping off them. Firestone or Air Lift come to mind. That is probably the best option, unless you go all out with a complete air ride rear axle conversion. Kelderman makes a great kit, but its spendy..

Is your wedge a tandem dual, or a triple axle? Personally have only pulled 2 3axle trailers. They were both tag along, & were loaded with a 9k, & 11k lb boat. Don't really know how a triple pulls empty..

 

Just to the left of the fender mount it looks like the overload/helper is slightly engaged. It could act with a small catapult effect when bouncing along overpasses, expansion joints, & bad roads..

That sucks about fender mount location. I've seen a few guys complain of no good place to mount them over on the hotshot fourm too. Could be jarring to bump against that also..

You've got a 51' trailer right? To be legal everywhere except CA, it should have a 41' kingpin to rear axle measurement. That leaves at least 10' rear axle to bumper, or tail swing. I guess if you have much more than that you could see about moving the tandem back a few feet, but that may require a structural engineer..? Depends on how strong the main beams are, because you'd be lengthening the KPRA distance. They'd be spanning a greater distance, & have to be able to support more weight. Could be feasible, but could get expensive..

It sounds like you are going to get the Firestone air assist, which sounds like a good move. Hopefully with that, & relocating the fender mounts you'll be good.

I also gather you are not a big fan of the TPT wedge. (Don't think I'd be after how they treated you) Maybe just trade it on something you like better while it's still new & the paint is shiny..

Just my thoughts, maybe someone with more wedge knowledge can tell you if this is normal..

 

Yeah, that's gn450 is a nice looking unit. Looks like a 4500 truck in the ad's. If you were very cautious about the way you load it, you might be able to pull it off with the 3500. Not that I like it, but I see 3500 pickups dragging 5car mini's up & down I95 all the time..

My post came out weird. Some of it is above in the quoted area..

 

Are your axles square to the center of the king pin??? That is, when measured from the exact center of the king pin to a specific location on or near the end of the axle. Does the measurement match EXACTLY when measured to the EXACT SAME location on the other end of the axle????

I have built many trailers of various sizes, and side to side wobble is often caused by an axle being out of square... Especially if only 1 axle is out of square... Or worse yet if both axles are out of square in opposite directions.

Something that is easy to check... And food for thought

 

Oh shoot, this just hit me. What about maybe trying to add shocks to the trailer? My spring ride gooseneck didn't have them, maybe your wedge does not either.? The welder you've been using could probably get done easily.

Granted my new trailer is air ride, but it does have shocks also. When empty I can't even tell it's back there.

 

Back and forth meaning front to back and visa versa?