question about body flexing, and twisting

[rustytoolss]

Just wondering about if anyone has had any issues with there foamie when the trailer twists or body flexing. Just wondering if flexing has caused foam to crack. Or does the PMF keep the body rigid enough to help prevent any effects of flexing/twisting ? I have not done any PMF on the foam of my trailer as of yet. My TTT will be 6' wide x 6' tall x 9'long cabin sizes. 2" xps . And is built on a pop up frame.

[lthomas987]

Just wondering about if anyone has had any issues with there foamie when the trailer twists or body flexing. Just wondering if flexing has caused foam to crack. Or does the PMF keep the body rigid enough to help prevent any effects of flexing/twisting ? I have not done any PMF on the foam of my trailer as of yet.

My trailer felt more flexible before the PMF. It stiffened up a great deal after.


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[ghcoe]

My 5x8x4 is solid. Lots of interior support though with shelves and bulkhead.

[bonnie]

Mine too is solid. My neighbor and I lifted the entire cab onto the trailer.


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[Don L.]

I wondered about the twisting aspect too, and mine is a little bigger than yours. It is pretty rigid, no signs of cracks or anything.

It is definitely worth keeping that in mind as you build though. Since mine is so big I used 3/4" ply for the floor, screwed with adhesive to the frame. And all the cabinets that are attached to the floor are fastened with many screws and "L' brackets, then the cabinets are glued and screwed into anchors in the foam. I think all the cabinets, seats and bed framing helps stiffen things up.

[rustytoolss]

I wondered about the twisting aspect too, and mine is a little bigger than yours. It is pretty rigid, no signs of cracks or anything.

It is definitely worth keeping that in mind as you build though. Since mine is so big I used 3/4" ply for the floor, screwed with adhesive to the frame. And all the cabinets that are attached to the floor are fastened with many screws and "L' brackets, then the cabinets are glued and screwed into anchors in the foam. I think all the cabinets, seats and bed framing helps stiffen things up.

I used 5/8" plywood for floor material. And have several cabinets mounted to the floor. One that extends to the ceiling. And two that are mounted to the walls and ceiling. Also will be having shelving on three walls.

[tac422]

The Big Pink hasn't had any problems with Flexing or twisting.

[rustytoolss]

Thanks Guys,

[Don L.]

Something that helps reduce the stresses on the walls is to build the lower cabinets with 3/4" ply and the upper ones with 1/4" plywood wherever it can be worked in. Keeping it lightweight up high so there is little inertia or torque on the walls. I think that's how you would say it, makes sense I hope?

[GPW]

Quote: "Keeping it lightweight up high so there is little inertia or torque on the walls. I think that's how you would say it, makes sense I hope? “ ... Acceleration is mass times speed ... less weght , less inertia ...
Our Foamie trailers are Flexible to a degree and bends rather than breaks ... Watching a British driving show , they were towing several different trailers across some ridiculously rough terrain, and the first thing to go was a plywood trailer which didn’t flex ( you could see it ) and it just collapsed under the strain , another more unibody trailer did OK ( survived ) ... We bounced the Foamstream off a curb first trip out , and there was no problem , and with low mass didn’t rebound , just came quickly back to it’s stable state on the road ... no damage , it just flexed ...

[dancam]

Correct. Just keep in mind when you build something flexable, then add something stiff(brittle) the stiff part will either break or tear out of the flexable part. So if you add rigid stuff like wood or metal remember it either has to have enough flex to flex or enough rigidity to stay rigid in what your doing.

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[Don L.]

I see what you mean Dancam.

FWIW, something I noticed on my standie is if you are standing next to it and push on a wall or corner, there is'nt much flex, the whole thing will rock, it's pretty stiff.
Only if you push on a section of wall with nothing behind it like a cabinet or window or ledger then you'll see some give.

I think having only 2 wheels and a hitch (3 points) of support on the frame it can't really put any torque or twist on the frame.
My camper has 4 jacks welded to the frame (old car jacks) that stabilize it when camping (or else it would tip backwards badly when unhitched). That makes 4 points of support and if I were to crank one up real high that would put some torque on the frame (which transfers to the walls) , so I try to be aware of that when I am leveling it.
I could test it by supporting the camper on 2 opposing diagonal jacks mostly, but not sure I want to stress it needlessly.

[dancam]

but not sure I want to stress it needlessly.

You dont, lol.

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[wagondude]

I think having only 2 wheels and a hitch (3 points) of support on the frame it can't really put any torque or twist on the frame.
My camper has 4 jacks welded to the frame (old car jacks) that stabilize it when camping (or else it would tip backwards badly when unhitched). That makes 4 points of support and if I were to crank one up real high that would put some torque on the frame (which transfers to the walls) , so I try to be aware of that when I am leveling it.
I could test it by supporting the camper on 2 opposing diagonal jacks mostly, but not sure I want to stress it needlessly.

You should not use the jacks to "level" any trailer (even production trailers). They are intended to stabilize. Levelling should be done at the wheels with the weight on the suspension to avoid stressing the frame. The misconception of levelling with the jacks is why you find so many popups with failed lifting mechanisms.

[Don L.]

You're right Bill, that's a good thing to point out.