Does this frame cross-member break matter?

[joebedford]

Yes, I suppose it matters. I was chasing a plumbing issue and discovered this when I opened up the underbelly of the rig. At first I thought it was one of the black tank supports but on closer inspection it appears to be a cross-member. It is a steel bar at the top and bottom with zig-zag rod welded back and forth.

It's in a very bad position near the tanks and water lines. Welding would be problematic to say the least. I wonder if a steel L with bolts would be sturdy enough?

[j-d]

I read all that Lippert information linked above and thought:

Rather than let it break then fix it, just build it the way it should be, the first time... It seems Lippert knows how it should be done...

[joebedford]

OP here:

Well, to wrap this up hopefully for now and forever, I got the rig back from the repair shop. You can see from the photos that they welded the break where the cross-member attached to the frame and rebuilt all the webs in the cross-member. We'll see if it hold up.

They dropped the bottom coroplast enough to look at the other cross braces and none of them is broken.

They said two other things:

1) Morryde X-factor braces would help
2) LT tires put more stress on the frame when scrubbing sideways!!

$1100CDN for the repair. No word from Keystone, Thor, Dutchmen or whatever they are these days if they're going to help out with the cost.

[joebedford]

FWIW, Lippert has said that bending over the tabs on the cross-braces is correct for my rig. Still no word from them on repair procedure. They say the break is unusual but there are plenty of reports of frames folding over on the internet.

It was suggested to me that Morryde X-Braces would stiffen up the frame. I'm not convinced. Anybody have direct experience with X-Braces?

[joebedford]

myredracer wrote:
Can you see into the floor assembly from above the floor anywhere like maybe holes for piping?

It's 2.5"
thick:

[myredracer]

Can you see into the floor assembly from above the floor anywhere like maybe holes for piping? You could maybe use a piece of wire to see how far down it would go before touching the fabric? Or a pipe inspection camera? In a house you're usually like 5/8" plywood supported on 16" centers or sometimes a bit more but then the plywood needs to be thicker. I know some trailers have weak floors and you can see them sag when walked on but don't know if it's because of too thin plywood or joists too far apart. Maybe someone here can elaborate as I'm interested in knowing anyway.

joebedford wrote:

myredracer wrote:
You can't possibly have the OSB or plywood floor supported only on the I-beams and crossbeams.

I have the advantage of many more photos of the underbelly. I have not seen anywhere the floor touches the cross-beams. The floor seems to be entirely supported by the frame rails and the "wing extensions" that go about 10" outside of the frame rails - nothing in the middle.

The upper 5th wheel section of the RV has the square aluminum tubes under the floor like you describe but I see no signs of anything like that in the lower level.

The floor in the 5th section is OSB. The floor in the rest is foam core plywood skin. It probably has internal studs like the walls. Maybe that's why no external support?

The kitchen center island is on top of this section of floor. The fridge and stove are in a slide.

The garage has a couple of heavy beams but there's one section of floor with no external support. At least the fuel tanks have good support. I've never noticed any floor flex with one heavy bike and heavier trike in the garage.

[joebedford]

myredracer wrote:
You can't possibly have the OSB or plywood floor supported only on the I-beams and crossbeams.

I have the advantage of many more photos of the underbelly. I have not seen anywhere the floor touches the cross-beams. The floor seems to be entirely supported by the frame rails and the "wing extensions" that go about 10" outside of the frame rails - nothing in the middle.

The upper 5th wheel section of the RV has the square aluminum tubes under the floor like you describe but I see no signs of anything like that in the lower level.

The floor in the 5th section is OSB. The floor in the rest is foam core plywood skin. It probably has internal studs like the walls. Maybe that's why no external support?

The kitchen center island is on top of this section of floor. The fridge and stove are in a slide.

The garage has a couple of heavy beams but there's one section of floor with no external support. At least the fuel tanks have good support. I've never noticed any floor flex with one heavy bike and heavier trike in the garage.

[myredracer]

joebedford wrote:
For the little I've seen, there's nothing I've seen that's holding the floor other than the frame rails.

I think you will find that there are floor "joists" that run in a fore/aft direction that are supported by the cross beams/joists. In our TT, the fore/aft joists are 2x2 thinwall aluminum tubing on 16" centers or thereabouts. Our TT also has open web crossbeams like in the OP's photo, as I encountered one when pushing a 4" furnace duct through it, blind from above. You can't possibly have the OSB or plywood floor supported only on the I-beams and crossbeams. There will also be a layer of Darco fabric on the underside of the floor. In our TT, when the factory needed a hole for the duct through the floor, they just hacked out one of the alum. joists with a sawzall - and it's in a area of higher floor loading.

There is precious little info. or photos out there on how Lippert's frames are built and what the design(s) look like.

I would guess that the web's rods in the photo (perhaps call it a "crossbeam" for clarification) underwent a lot of stress from parallelogram action of the bottoms of the I-beams flexing left/right relative to the top of them plus you'd also have the weight on the fore/aft joists bearing down on top of the crossbeam causing deflection in it. If you have something heavy above like a kitchen, it would add more stresses to the joists and crossbeams, esp. from motion when travelling.

The floor (plywood or OSB) would act as a diaphragm (in eng. parlance) and create a stiffer connection of the tops of the I-beams in a horiz. plane all around the trailer's frame while the bottom flanges of the I-beams could have more freedom to move. Perhaps the upper and lower flanges of the crossbeam had different amounts and directions of force applied to them relative to each other as a result. There is also the possibility of sub-standard welds contributing to the failure. Dunno, just thinking out loud...

Would be interesting to put a camcorder down there and see what happens as you tow it around but I would get repairs done asap. Look forward to hearing about any remedial work and seeing more photos. I would really recommend having a reputable frame shop look at it unless you are well-versed in working on these frames. We had a detailed insp. done on a previous TT for $200 and was was well worth it.

[MEXICOWANDERER]

I would not drag a trailer 5 feet without boxing in the frame area of the hangers. The very best way is to rivet the box or fish plate. If welded the entire distance plus six inches fore and aft the extreme distance of hangers run inch long beads with inch no weld gaps in between.

That is why I recommended the Allstate 275. It does not heat up the parent metal as much as 6013 or 7018

I have towed trailers over washboard road so fiercely rippled that when I tried driving just a pickup truck fast enough to try and cancel the pounding it tore a riveted shock mount pad to frame loose from the truck (year 1984). I never had a frame crack. But then again I reinforced the frame first. I dragged a 31' Prowler to Tikal Guatemala then to Gracias Honduras with no problems. You can bet your bippy the terraceria (gravel road) of 90-miles length would have tested the frame.

My God, they are building "dumplings" to baby-sit from one RV park to another. How sad.

[joebedford]

soren wrote:
Are several of the web rods in that truss snapped in half

I was about to say "Nah" but on close inspection of the higher resolution original photo, it appears that you're right - at least two of the rods are broken. Yoiks!

[Lynnmor]

You can find the photos in my library. I made the yellow and red items that you will find. A brief description is with each photo.
Library

[Lynnmor]

soren wrote:
Are several of the web rods in that truss snapped in half, as they appear to be? Might be interesting to get a Go Pro video of that area while the trailer is heading down the road. I'm guessing the whole mess is about as stiff as a bowl of spaghetti.

One member on here did exactly that. Wet spaghetti is what he found.

[soren]

Are several of the web rods in that truss snapped in half, as they appear to be? Might be interesting to get a Go Pro video of that area while the trailer is heading down the road. I'm guessing the whole mess is about as stiff as a bowl of spaghetti.

[joebedford]

Yes, photos please.

For the little I've seen, there's nothing I've seen that's holding the floor other than the frame rails.

I had the same thought at you about the floor holding the top of the rails in place - for far, I've found exactly ONE screw through the floor into the rails.

[Lynnmor]

joebedford wrote:
Did you bolt in triangular gussets inside the frame?

No, when you think about it the current cross-members have little lateral strength and attaching gussets would be of little value.

Think about it this way; if you would work the spring hangers side to side with a very large adjustable wrench, that is what your suspension is doing.

When you mentioned the tabs on the top of the frame, you should have floor joists above the frame for support. The floor should give some help to the top of the I-beams and the added trusses will keep the bottom in location.

I have photos that I can link later if you want.