Porpoising (Bucking) Fifth Wheel

The_Painting_Teacher wrote:
So it sounds like many people have different ways or ideas to prevent porpoising. I'm telling you one way what work with me. Take it for what it's worth. Camp on!

Different Strokes for Different Folks!

So it sounds like many people have different ways or ideas to prevent porpoising. I'm telling you one way what work with me. Take it for what it's worth. Camp on!

One more think that will help is shocks on the 5er. I added then to mine and the difference in towing was great! Much smoother, and far less (like zero) Porpoising on bridges and concrete roads.

Porpoising is pretty much a thing of the past for us since I installed the Trail Aire Tri-glide pin box on my unit. We used to have a real "buckin' bronco" ride on some of the roads we use frequently. Now we may get a little bit of a "buck" but it dampens out fast and the difference is pretty dramatic. We run at a (weighed) 24% pin weight, but it was almost that before we changed out the pin box. I'll be adding a Splendide combo w/d up front this spring and I may have to re-balance a bit after that. But I'm not overly concerned about it.

rhagfo wrote:

RCMAN46 wrote:

MrVan wrote:
We too get the "porpoising" when going over bridge joints or a really rough road elevation change. Have over 2,500 lb pin weight. Have tried several things including changing rear shock absorbers. Nothing seems to make much difference. Pulling a near 14,000 lb 5th wheel when fully loaded. Have learned to live with it and have traveled the same roads enough now so know where to slow down to reduce the drama. First few times thought the rear wheels had lifted off the road. .

You have less than 18% pin weight. That is not enough for a 5th wheel to behave.

Raise your pin weight to 25% and I bet the problem will go away.

Is the 5er in question level when towed? Towing nose high will add to the issue.

Will check the next time we tow for actual pin weight. The fresh water tank is at the rear of the 5th wheel and we usually don't put more than 10 to 20 gallons in it. That has a big effect on pin weight
The RV is level when towed. it kind of feels like the RV is rotating around the two axles. Doesn't do it very often but when it does it is a bit disconcerting.

I put 40 gal of water in the fresh water tank ,it sits right over the axels,really quiets the fiver down on rough roads,im at approx 20% pin wt.

I solved all that with a MorRyde Hitch pin. I use cruise control all the time.

Nothing u can do about the roads

packnrat wrote:
too bad our governments refuse to maintain our roads, with all the rd taxes they collect.
fuel, land, sales, tolls and "other" ?fees?

They use that money on bike paths and buses, not all is spent on roads as it should be. You certainly can tell how a state spends that money tho when you cross state lines.

RCMAN46 wrote:

MrVan wrote:
We too get the "porpoising" when going over bridge joints or a really rough road elevation change. Have over 2,500 lb pin weight. Have tried several things including changing rear shock absorbers. Nothing seems to make much difference. Pulling a near 14,000 lb 5th wheel when fully loaded. Have learned to live with it and have traveled the same roads enough now so know where to slow down to reduce the drama. First few times thought the rear wheels had lifted off the road. .

You have less than 18% pin weight. That is not enough for a 5th wheel to behave.

Raise your pin weight to 25% and I bet the problem will go away.

Here is something to imagine ,the porpoising is momentarily unloading the rear axle .
That is the formula for a jack knife.
Raise your pin weight