I would be concerned. I would think there is a stress crack somewhere.

I would agree that some more investigation is in order.

Brian

jlsinz

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The deflection that you describe is quite normal . . . although most owners never realize this because the usual transfer of weight from the landing gear to the pin box is accompanied by hitching to the TV and the associated compression of the truck suspension masks this.

How do I know this? I use a pin tripod to stabilize the front of our 5th wheel. Adjusting the weight shared by the landing gear and the tripod (by lifting the landing gear a small amount) can significantly improve the stability of this "three point" front of trailer support. Along the way to figuring this out, I discovered that starting with the tripod firmly under the pin (on a concrete surface) I can raise the landing gear almost a full inch before the landing gear pads lift from the concrete. This is the flex of the entire front of the frame and the pin box as the weight transfers from landing gear to pin. This is the deflection that you have also observed.

Rob

Cate&Rob , that is not the same deflection if I understand correctly. You are going off pin to landing gear, a distance of what? 6 feet? Pin to front cap, a foot or so?

Scott'n'Wendy

I understand what you are saying . . . but the frame flexes within the body. I have never measured between the pin box and a reference point on the body. If the body “stretched” that inch, it would be torn apart. I was very concerned when I discovered that I could lift the landing gear almost an inch before the weight transferred completely to the pin tripod . . . but, that was many years and many thousands of miles ago. All seems to still be fine.

Rob

My previous brand trailer was a Titanium. Pin box deflection was a frequently talked about issue. When hooking up to the tow vehicle, the acceptable pin box deflection was up to 15mm.This was determined be measuring how much the pin box retreated into the nose. If deflection was high, it almost always ended up being cracks in the frame where the somewhat vertical part of the frame was attached to the main horizontal part of the frame. They were fibreglass bodied but didn't hear of any exterior surface cracking because of it?
Now the Titanium is quite a different animal from a standard 5th wheel, so my thinking may not apply, but if it was me I would be inspecting the forward frame welds closely.