How to Correct Fifth Wheel Fishtailing on Lifted Trailer

Updated 05/15/2020 | Published 03/01/2017

Question:

My name is Jim, i have a 2004 39-foot Sandpiper fifth wheel, i have had the trailer since it was new and never had a issue towing, its been through two tow vehicles a ford f250 and a Chevy Duramax. i just purchased a 2015 dodge Mega Cab and am having fits with the trailer its fishtailing anything over 50 mph. the new truck sits quite a bit higher stock than the other trucks so the first time i towed it it was all over the road. the trailer was nose up so i flipped the axles and adjusted the pin, the trailer sits dead level now and it still is doing the same thing , Im at a loss for the next step. Also when i bought the truck it has the four point bed mount for a trailer hitch i purchased adaptor for my hitch it is a manual slider the same one i have always used, i thought i may have had a blown rear shock so i bought new bilsteins on the rear. Thanks

asked by: Jim K

Helpful Expert Reply:

Tall/lifted trucks are not ideal for towing since they can lead to an out-of-level (nose high) condition on the trailer, which in turn can lead to issues with sway. Even though you have taken steps to get the trailer level again (the axle over-under kit, which gets you a few inches of additional height, and the pin box adjustment) you then still have a related problem: a higher center of gravity for the entire towing system, truck and trailer.

The higher the trailer's center of gravity the more side to side sway you will have, since the top of the trailer is now further from the road surface. There is no bolt-on item you can add to fix this issue but you can address it to some degree by careful trailer loading. Rear-end trailer sway often indicates too little tongue weight (TW) at the nose of the trailer.

I suggest loading the trailer with more weight up front. You can do this in increments until you find the point where your trailer sway is minimized.

expert reply by: Adam R

Jim T.

5/11/2020

I have a Jayco eagle Premier 375BHFS, pulling it with 2017 Dodge ram 2500 4x4 diesel, with companion B&W hitch, the rv has a morryde pin box, the back end is all over the place, ANY IDEAS? new tires on both, im about 2 inches from the bump stops on the truck.

Chris R.

5/13/2020

Is the trailer pretty level when hooked up to your truck? If not, you'll definitely want to adjust the Companion or pin box to raise/lower the trailer nose. Other than that it's really just a matter of trying to re-distribute weight inside the trailer like Adam mentioned above. Try pushing more cargo up towards the front to put more weight on the hitch. This typically goes a long way towards eliminating a lot of unwanted sway.

Jim T.

5/13/2020

@ChrisR , the rv is stock with no person items in it. all the tanks are empty, and it squats my truck quite a bit, i have ordered air bags, should it be measured from the frame to the ground in the front and back?

Chris R.

5/15/2020

@JimT Rear suspension enhancement will help a lot with this - both regards to the squat you're getting along with sway/instability you're experiencing on the road. An easy way to measure for a level setup is to measure the wheel well clearance on both the front and rear wheels - the difference will show you which end is sitting higher (and by how much).