2015 fuzion 345 king pin box sag issue?

[Sandfreak]

Noticed today while unhitching the king pin box where it attaches to the frame has a lot of flex IMO. Set the fuzion back on the truck on it looks like the kingpin box sags into the trailer a good inch or so. Is this normal on a Keystone? I just dont remember my old 08 gearbox having any sag..

[JRTJH]

There is a certain amount of flex that occurs with any metal structure. If it didn't flex, it would destroy itself when being towed over the road. That said, there have been a few reports on the forum about broken welds in the pinbox area which caused damage (cracked fiberglass) to the sidewall system. The damage was reported at the corners of the bedroom slideout, typically on the forward lower corner of the framing for the slideout.

Possibly you could measure from the front corner of the lower part of your trailer to the most forward part of the overhang (on the side of your RV) with it unhitched, sitting on the landing gear, then hitch it to your tow truck, raise the landing gear and remeasure that same space. Be sure to mark both spots so you know you're measuring the same space. If there's any significant difference, you may have excessive flex from a broken weld or from some other abnormal problem.

Also, from your description, where you say the pinbox "sags" into the frame. If you have an air cushion pinbox, there's going to be some "cushioning" as weight is placed on the pinbox, That is how the structure inside the pinbox "absorbs" the vibrations during towing. So depending on the type of pinbox you have, it may be normal.

If you're unsure, then I'd urge you to discuss it with your dealership service department.

[bsmith0404]

You could also pull the sheet metal down under the overhang so you can get a good look at the frame.

[tzman]

By all means, pull down the panel and check the pin-box frame welds. they can break. Don't ask how I know.:facepalm:

[bobbecky]

A little over a year ago, we had a broken frame on our rig. I managed to find a mobile RV repair guy who is also a welder. After making the repair, since we already had the Filon pulled down under the front of the rig, we dropped the pin box, and he found numerous cracks and broken welds in the frame above where the pin box attaches. He made repairs to this area also. Once all those repairs were made, there is no sag or movement in the frame or pin box. It would be a good idea, if you are seeing excess sag in the pin box, to drop the pin box and inspect the frame in that area before other damage occurs. We had maybe 40,000 miles on our rig at that time, and many of them over some very bad roads.

[Sandfreak]

Thanks guys for the info. Have a mobile rv repair check it out next week.