Unstable

[Hollywoodtx22]

I have a 2018 Ram 2500 4x4 Cummins that I put a leveling kit on several years ago. I’m running 35x12 50 tires on the stock 18” rims. My dad has the exact same truck but everything is stock and he added a fifth wheel to pull his 37 ft camper. I recently install a sliding 5th wheel hitch in my truck to pull his rv. I pulled this past weekend and could not get over 55 mph without it starting to sway dangerously. Any ideas what might be going on?

 

[White six four]

What's the weight of the 5th wheel? What kind of leveling kit is on your truck?

 

[mtofell]

I recently install a sliding 5th wheel hitch in my truck to pull his rv.

Sway generally comes from a lack of tongue/pin weight which is rarely a problem with a 5th wheel since so much weight is on the pin. Dumb question but I have to ask - is the hitch set forward when towing? The weight of the trailer being put on the truck must be over or slightly ahead of the rear axle centerline. It's really just a matter of physics - trailer weight on or ahead of the rear axle and you should be good to go. Again, sway with a 5th wheel is almost unheard of.

 

[2003F350]

Might be a dumb question but what tires do you have, and what pressure did you have them set at? Remember that when towing a load you need to air them up to handle the weight and stiffen them up. If you left them at your normal cruising pressure then you very well could be feeling sway.

Otherwise I agree with mtofell - properly set up a fifth wheel shouldn't sway unless you're in high winds.

 

[Gordo2212]

When you start changing up things that are stock (like tires and lift/leveling kits) , that has an affect on the towing capabilities of the truck.

I’ve read this is especially true with lift kits and things that deal with suspension.

 

[Dinky]

Looks like everyone covered the rear end side. Have you looked at your front end at all? ball joints, track bar, steering box, sway bar, and shocks? I know the OEM track bar is only good for about 30k ball joints soon follow.
being how you are towing the front end is a touch lighter now and could cause some move ment.