Structural failure at rear door header

[Boonie]

As I get ready to do final welding of my revised camper shell, I have observed what may be a failure of the FWC "flex frame design". Although only those of you that have torn your camper apart may be able to answer this question, I am going to ask it here in a new topic rather than on my build page.

At the 2x1 rear door header ('81 construction) I have cracks in that header where the door side posts attach to the header. I am sure that as the left and right sides of the camper "sway" when going down the road the only member that resists that movement is this 2x1, thus the cracks. If I reinforce from the outside it interferes with the roof closing. If I reinforce on the inside it interferes with lifting mechanism. If I reinforce on top (as Pokybro did) I would have to raise the height of the top rail all the way around. If I reinforced below It would reduce the door opening height. The only method that makes sense is to cut and reinforce internally (which I did in a similar situation when I extended the Jeep frame 24").

What have you done?

 

[Vic Harder]

Boonie, I am totally in awe of what you are doing with your camper. Very cool.

For what it's worth, I don't think either of my two camper builds had cracks in that area. Here are a relevant pic, or is this not the right area?

 

[Boonie]

Vic,

Yes, above the 26" mark, above the black (gasket?), almost to the far left of the picture where the door side post connects to the header and the lift mechanism attach.

Boonie

 

[Boonie]

A picture is worth a thousand words, so here it is.

 

[Vic Harder]

I notice your frame is not doubled up like mine is. Mind you, I didn't take mine apart as far as you did, so didn't see that area. What about spreading the load by introducing a doubled up vertical member to the right of the door frame one you have now?

 

[Beach]

As Vic mentioned you can double up or have corner gussets welded into that open square to the right of the upright. I would fab a "T" plate and weld it in place over the cracks after they have been repaired/welded.

 

[Boonie]

Vic,

Yes, I will be doubling up the vertical members. (I added a picture on my build that shows partial verticals I mocked up to get dimensions.) However, that will simply move the stress point. I still think I need some reinforcement. Maybe a flat plate on the inside.

Boonie

 

[Boonie]

Beach,

You are thinking along the same lines as the flat plate I mentioned. Thanks for the input.

Boonie

 

[PokyBro]

Boonie,

I tried to find a good picture in my album showing the same crack I had, and how we went about fixing it, but no luck. As I recall I had my guy weld the crack, and then as you mentioned above, I added two rows of 1”x1” stock above the door because I wanted more height and to increase the bed overhang depth, but it also served to create a more sturdy doorway.

in my opinion, if you put a 1/16” thick plate on the front and back and covering over the crack with welds on each end, in addition to welding the crack and then grinding down the bead a bit before putting the plate over top, I don’t think it will interfere with the outside lid coming down, nor the lift panel hinge mounting on the inside. You may have a little irregularity, but not enough to matter. Remember the tube thickness on you frame is probably less than 1/16” thick anyhow.

Good luck, and glad to see you digging back in. Keep the pictures coming, it’s fun to watch.

Poky

 

[Boonie]

Poky,

Early in my build I mentioned my self imposed height limit so as to fit in my garage and I think that very first picture is the only one that shows my camper in relationship to the garage door. I'm holding my breath that my Fan-Tastic vent will clear. That fact limits me from reinforcing by adding above the top rail. By the way I do plan to gain some standing height (I'm 6'-2") with longer lifting mechanism and longer fabric sides.

Also I'm still bummed that your location now reads Salt Lake City.

Boonie

 

[camelracer]

I've had FWC repair that area twice on my camper under warranty. It was evidenced by a crack in the siding at the upper right door corner. I didn't get to see it when it was apart so I'm not sure exactly what they did.They did say they replaced a 1x2 tube with 2 1x1 tubes.

In any case it didn't work since it has cracked a third time. Being out of warranty now I'm not going to spend the money for them to do another temporary repair. I've just sealed the crack to keep the water out.

 

[Boonie]

I wish the fix camelracer mentioned would have worked because it does make sense. From what little I remember about structural loads, the crack results from tension along the bottom cord. Replacing the single 1x2 with 2 1x1 doubles the members capable of resisting tension. Unfortunately it is still a single member on the bottom cord with two in the center, but this idea is still a contender.

Thanks camelracer

Boonie

 

[Beach]

Just some thoughts as to repairing this; Noticing the cracks begin at the weld, which is the weakest area of the aluminum due to heating during the welding process. Since this area wants to flex and you are limited by original design on how robust you can modify it, it might make sense to repair the existing cracks and install the T plate with rivets and bed it in place with 5200 or a flexible epoxy like Gflex. You would need to research the epoxy type/brand for this application and all surfaces would have to be prepped(abraided) properly for proper bonding. Additionally the T plate inside angles should have a radius instead of a square right angle corners(similar to aircraft construction) to reduce the chance of cracking in the future.

 

[Vic Harder]

Curious minds want to know why this problem isn't more common.

 

[DLN]

Just a thought, if you were to change to the newer rounded corner door you could potentially solve the issue with a pair of radiused 1/4" aluminium braces at each corner.

 

[camelracer]

Just a thought, if you were to change to the newer rounded corner door you could potentially solve the issue with a pair of radiused 1/4" aluminium braces at each corner.

I've wondered if that's the reason FWC went to the rounded doors.

 

[Boonie]

Curious minds want to know why this problem isn't more common.

Vic, If you listen closely you might be able to hear the sound of readers running out to their camper to check for cracks!

 

[Vic Harder]

Vic, If you listen closely you might be able to hear the sound of readers running out to their camper to check for cracks!

LOL. I do wonder if the rounded doors are a "fix" for a problem that is more prevalent than we know.

 

[Forrest]

I have an older Grandby that I am in the process of updating b/c of crack on both sides of the door, top and bottom (one side) and the door frame itself. I think over tightening of the turnbuckles, 8ft bed flex w/ only a partial aluminum fame and off road was the magic combination. I believe this is why FWC has the radius doors and windows now and beefed up their framing. FWIW, recently got to look at 2011 framing and its way beefier and better made than in 2000 Grandby. Its kool to see the progression of building.

 

[Boonie]

Forrest,

Welcome to WTW.

I agree with your "magic combination", especially off road and since this is where I will be using my rig, I want to find a fix.

Boonie