Correcting 5th Wheel Trailer Sway with Occuring with New Taller Tow Vehicle

Question:

I just bought a new truck. I went from a 2 wheel drive truck to a 4 wheel drive truck. When I pulled my fifth wheel camper the last weekend, I noticed a slight fishtail type movement at highway speeds and noticed the camper seems higher in the front when hooked up to the new truck. Would adjusting the pin box moving it up some take the fishtail like movement out of the trailer when towing it?

asked by: Trey

Helpful Expert Reply:

If you notice degraded handling in your new towing setup and you can see that the trailer's nose is now higher than it was with the old vehicle then you will be able to correct that fishtail motion by restoring the trailer to a level stance when it's hitched. A trailer that rides nose-high tends to have too much weight in the rear-end, which can act like a swinging pendulum. Restoring the hitched trailer to a level position will help.

In some cases this can be done by adjusting the position of the trailer pin box on its mounting wings. If you have room on those mounts to shift the box upward and if you have adequate clearance between the bed rails and the trailer's overhang, then this is the way to go. Please refer to the linked diagram that shows the recommended clearance between truck and 5th wheel trailer.

When it is not possible to move the pin box another solution is to install an axle over-under kit which lifts the height of the trailer by swapping the positions of the axles and leaf spring stacks. We have two such kits, parts # K71-384-00 for 2-3/8-inch axle diameters and # K71-385-00 for 3-inch axles. You will need one of the appropriate kits for each axle. These kits provide a height gain in the trailer equal to the sum of the axle diameter plus the height of the leaf spring stack.

Please refer to the linked video and instructions.

expert reply by: Adam R