I have a 39 ft. Keystone Alpine toy hauler.  Previously, I towed it with a long bed truck as a 5th wheel.  Zero problems.

Now I am towing it with a goose neck conversion with a standard bed pickup.   SOMETIMES when  I am going above 60 mph, my pickup starts rocking side to side, sometimes pretty radically.

All tire pressures are correct, hitch is secure and correct.  Any thoughts on the cause or cure?  Or is it just the nature of the beast?

We’re both trucks completely stock?

Interesting problem. I have heard of trucks porpoising(sp?), but not rocking side to side.

The gooseneck may play a role, but I don’t know enough about it to diagnose

Good luck. Having towing being unnecessarily more difficult would be unacceptable

IDK the answer, but that is a big ass trailer.  Seems like 1 ton+ territory.

I’ve never towed a trailer that long or that heavy nor used a gooseneck hitch. But it seems if the trailer started to fishtail then the pressure on the gooseneck could cause the truck to rock from side to side. Or so it seems.

Any changes to loading/weight distribution on the trailer?

I have a 37’ Alpine, Chevy 3500 drw, B&W companion 25k hitch, it’s a solid ride. Do you know anyone with another HD truck that can pull your camper to see if it’s the truck or the trailer? What model truck are you towing with? Is the camper level when hitched or nose high? Are you running the stock Hispec tires? 110psi?

The shorter wheelbase of the tow vehicle = more sway.
Sway is influenced by the center of gravity of trailer over its axles. I don’t know squat about the hitch being advertised but video below is a great demonstration.



In your situation you have a long trailer that is also a toy hauler so its cargo area is behind its axles. You now have a shorter wheelbase vehicle to tow it. The longer the wheelbase of the tow vehicle the less the influence the trailer has on it. You might can adjust your tongue weight (aka pin weight in your case) but might not be able to get enough to stop the sway. Being a fifth wheel/ gooseneck helps since it moves the hitch point forward but they still can sway.

Sway is dangerous if you ever break traction of your truck’s rear axle you’ll jackknife and the trailer will tend to roll your truck as it tries to pass you.

I may have missed this, but single rear wheel or dual?

Thanks everyone.  The problem is solved.  I had a rear tire on the truck that was out of round due to a belt separation. It completely failed as I was pulling into a dealership.

Glad you found it!

Was going to type check the tires. we've had many people with tires that held consistent pressure but had broken cords.

Glad you found that pulling into the dealership vs 60mph with a 39' trailer.

Absolutely!


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Not on the tow vehicle, but on the trailer.