5th Wheel Trailer Jerks and Pulls on Rough Roads

A member of the RVbasics Yahoo Group posted the following question.

“We have a 28′ 5th wheel we pull with the Ford 250 4X4 diesel. We have been on a great adventure . The roads are so rough it seems the trailer just jerks and pulls and gets knocked around something terrible. Does everyone have this problem, or is it just us?”

It is impossible to give specific advice given his general description so here is some basic advice good for all 5th wheel owners:

  • Except for extremely bad road or high winds your fifth wheel and truck should feel and perform as one unit. If it doesn’t find out why.
  • If your are experiencing a harsh or stiff ride, your truck tires may be over inflated. Your tires should be pressurized proportionate to the load for best ride. If you are experiencing a soft, bouncing rid your tires may be under inflated but bad shock absorbers are most likely you problem.
  • If you feel a tug/pull from the trailer which is disproportionate to the amount of pressure applied to the truck brakes adjust your trailer brake controller so that trailer breaking matches truck braking. You will usually notice this tugging at slow speeds maneuvering in parking lots and campgrounds where you’re just tapping the brakes, however, if the controller it too much out of adjustment you may also feel tugging during normal breaking. Also check the pendulum …if your break controller has one… for proper adjusted as it can contribute to tugging it is set too sensitive. Consult your Brake Controller manual for proper setup.Fifth Wheel traveling on the highway
  • If you feel the 5th wheel bumping when making a stop and/or jerking when accelerating from a stop, you have a problem with the hitch system. Check the hitch system for the following:
    • Obviously loose or missing bolts and pins on the hitch and pin box.
    • Even if all bolts appear to be tight they may not be tight enough. They need to be torqued very tight and just using a hand wrench wont necessarily get them tight enough. Look closely around the head of the bolts and washers to see if there are signs of wear or slipping.
    • Check the welding and framing where the pin box is welded to the trailer frame. This can be difficult since most 5th wheels have this area covered but use a flashlight and maybe a mirror to see as much as possible. You will be looking for broken/cracked welds and framing. It may be rare but it does happens.
  • Here’s a simple test you can do. With the trailer hitched, have your spouse hold the manual trailer brake and put the truck in reverse. Give the truck just enough gas to put some pressure on the hitch and watch for movement. Do the same with the truck in forward gear. You may have to repeat this procedure while you focus your attention on specific parts of the hitch system. Watch for movement in any of these places:
    • Where the hitch frame attaches to the truck bed.
    • Where the ‘head’ of the hitch attaches to the hitch frame.
    • Where the king pin connects the head.
    • The connection between the lower pin box and the upper pin box. This connection is bolted together and allows the height of the pin box to be adjusted. This gave me trouble after I adjusted the height for a newly purchased pickup.
    • Where the upper pin box is welded to the trailer frame.
  • If you are unable to determine the source of the problem consult a trusted RV service tech. His experienced eye will likely find it.

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As always, we welcome your comments, questions and advice on this topic.

 

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