Pinbox moves?

[Lightning55]

A friend has a Jayco 5th wheel that's about 4 years old and noticed that the pinbox seemed to move up and down over bumps. He couldn't remember ever noticing this before. Suspicious that something wasn't right, he raised and lowered the trailer off the truck and measured that the pinbox moved up and down 1/2 inch from the cap of the 5th wheel. He says it doesn't seem to pull any differently but I don't think this is normal. I'm no expert but it seems to me that the pinbox should remain firm with the trailer and not move, even slightly. Sounds to me like the pinbox is loose or broken away from the frame work of the trailer. Unfortunately, you can't see up in there without removing all the paneling around the pinbox which isn't as easy as it sounds. Does this sound like something serious?

[Pwrstrok]

I had that problem with a Sunny Brook. The cross member that the pin box was hooked to cracked on both sides, Had to cut it out and replace with thicker c-channel.

[Cummins12V98]

Check for movement at bolts. My holes were stamped 11/16” with 5/8”
Bolts. Mine did move a lot. Aligned pinbox to frame clamped and drilled holes to 3/4” and filled with 3/4” FRAME BOLTS.

Extended pinbox does move up at least 1/2” when hitched but I have 6k pin.

[BurbMan]

Lightning55 wrote:
Wow....150 views but only TWO opinions??

Not much else to add....the pin box should NOT be moving that much and likely indicates serious structural issues with the 5er. It will get worse over time and bumpy roads will accelerate the damage.

[Lightning55]

He measured the half inch movement about the half way point of the pinbox just under the front edge of the trailer cap. It's probably more movement at the tip of the pinbox.
He said the weight of the pinbox is probably less than 2000 lbs.
We attempted to remove some of the body paneling around the pinbox to see but stopped because we were certain that we'd create some damage to the thin aluminum panels trying to remove them. I think he's going to call the dealer next.

[MFL]

pinesman wrote:
Where should the measurement be taken? I have an extended pinbox so the closer to the end of the pinbox, the more pronounced the flex

Pin box styles vary, but with most extended pins, I'd measure between pin box and lower front of FW over hang (normally front cap bottom).

Jerry

[pinesman]

Where should the measurement be taken? I have an extended pinbox so the closer to the end of the pinbox, the more pronounced the flex

[Old-Biscuit]

When I inquired with factory rep 'What amount of flex' was normal he stated 1/4" MAX
More then that then pin box support structure or frame rails are under sized/braced

Should have your friend remove the overhang panel and visually inspect supports/frames/bracing when hitching & unhitching his 5vr

[Edd505]

There is a tolerance for movement, I do not know what it is. I was at a rally two years ago when one of the attendees had this issue. It was taken back to the factory and the front cap removed for measurements, they welded additional bracing to eliminate the amount of flex.

[12th_Man_Fan]

What is the pin weight of his rig? Mine is about 4000 lbs and it moves about half inch when I set it on the hitch and it has done it since it was new.

If he can see it moving when he hits a bump I suspect he has a bigger problem and he Needs to find out for sure.

[Lightning55]

Wow....150 views but only TWO opinions??

[fj12ryder]

If I noticed my pin box moving a 1/2" I would be pulling body panels to check things out.

[MFL]

If the pin box bolts are tight, the FW frame may be cracked. While there may be a small amount of frame flex, it should not move a half inch. If something is loose/cracked, it will worsen over time, and become serious.

Jerry