Porpoising (Bucking) Fifth Wheel

valhalla360 wrote:

RCMAN46 wrote:
Number one cause of porpoising with 5th wheels is low pin weight.

That was my thought. Are they simply addressing a symptom and not the problem.

Actually, light steer axle. Fifth wheel hitch needs to be moved forward.

RCMAN46 wrote:
Number one cause of porpoising with 5th wheels is low pin weight.

In some cases it may be truck design. I just saw a video of the big three HD trucks pulling 12K lb fivers up the New River Gorge (7%) in WV and the testers comment on the porpoising of the Chevy 3500 vs none in the other two.

RCMAN46 wrote:
Number one cause of porpoising with 5th wheels is low pin weight.

That was my thought. Are they simply addressing a symptom and not the problem.

Number one cause of porpoising with 5th wheels is low pin weight.

I'm using the Curt Q20 with slider in a 2500 HD Chevy.

Rancho 5000 adjustable shocks and Firestone bags. Set the shocks to max, with 40#'s of air in the bags. Made a ton of difference.

But it helps to get off the gas (momentarily) when you hit the bridge over passes.

I agree with you Paul, some stretches of road are very unfriendly to pickups (short beds) and 5th wheels. If we were stretched out a bit more on wheelbase it would make a difference.

Our rig is very stable. I think the combination of air bags on truck and ex flex on trailer makes it a great tow. Having said that there is one stretch of i5 south of Seattle that is like riding a rodeo bronc at speed. The only way to correct is slow to below speed limit for several miles. The lesson is I think any rig hitting the wrong stretch of oscillating road will behave like an amusement park ride...hitch and equipment regardless.

One of the best things you can do, if you haven't already, is add some suspension like the EZ Flex kit by Dexter. That virtually eliminated any issues with expansion joints, you notice them but they are no big deal anymore.

brittsnbirds wrote:
Mine does it! Bridges are a bugger. Found if I back off the gas as I hit them it softens the blow. Can't use the cruise with my unit. Lucky you.

What hitch are you using?

Mine does it! Bridges are a bugger. Found if I back off the gas as I hit them it softens the blow. Can't use the cruise with my unit. Lucky you.

Never seen or felt it myself. I suspect the hitch used may be the cause.