Pinbox vs fiberglass

[Butch83]

Our 2013 fifth wheel 3400RL has 1 1/2 inches clearance between pin box and fiberglass body. Since new the body has always flexed independent of the pin box when driving. On rough roads now the body almost touches the pin box when encountering a dip. I have inspected all roof areas, fiberglass siding, interior including thorough inspection of front area in closet and see no cracks or movement of any kind. Is this normal? Any similar movement in your trailers?

[dieselguy]

My cap in relationship to the pin box moves about 1/2" at most. You might drop part of the skirting around the pinbox under the bedroom and look for broken welds in the steel framework.

[jcurtis934]

I would tell you to glue a wooden matchstick to the pinbox standing up under the fiberglass and would make its length one half inch shorter than the distance between the front cap and box. This way, if there is more than the half inch...the matchstick, being really soft wood, will break. This takes all subjective eyeball error out of the picture. Hope your eyeball is wrong. John

[K0LCB]

I don't think it's normal to have that much travel in the pin box

[Razrbk]

quote:Originally posted by K0LCB

I don't think it's normal to have that much travel in the pin box

What's normal?

[rohrmann]

This past May, I discovered severe frame flex on the driver's side of our rig. I managed to locate a mobile RV repair guy who is also a certified welder who came to the campground we were at, and in addition to repairing the frame forward of the driver's side propane tank, he also discovered numerous cracks in the frame where the pin box is attached, which he spent close to an hour just grinding the cracks and welding the frame there. The pin box had not quite touched the fiberglass, but it had been close. Since the repair, it is as the trailer was when new. If you are having that much movement in your pin box, I would definitely recommend having the frame inspected and repaired, because it will not get better on it's own.