When I removed the delaminated filon and luan from my Class-C cabover I saw that one of the welds in the cabover framing is separated:Is it possible to have someone re-weld this, or does the proximity of foam/luan make it impossible?EDIT: I know the framing material looks like rusty steel, but I swear it is aluminum; the red stuff is old adhesive residue.I was thinking of getting some beefy aluminum corner brackets and screwing or bolting them to the framing as an alternative to welding. Anyone have any experience with this?

If it were me I would be thinking the same thing. Though I doubt that is aluminum as it looks rusty.Perhaps a thick "T" bracket? Many here sharper than I however.

The rusty looking stuff on the framing is just the adhesive that was used to join the luan to the foam and framing. I am pretty sure that it is aluminum, and not steel, because there is no rust anywhere on any of the framing in areas where the luan was completely rotted by water.

Welding looks impossible to me without removing the foam etc. from the area. Welding involves a lot of heat.I agree with Oasisbob that this probably isn't aluminum, at least gauging from the picture; it looks more like painted steel. Pictures can be deceiving, though. Aluminum doesn't rust, has a somewhat shiny gray surface, and is comparatively soft (many alloys can be cut or marred with woodworking tools). Welding aluminum is rather tricky work, I gather both because it is hard to keep clean (it oxidizes quite quickly on the surface) and because it has a very narrow plastic range between not joining together and forming a puddle of molten metal. I have absolutely no experience myself welding anything, though.I might try a reinforcing plate and some JB-Weld (and mechanical fasteners). If there's any easy way to do so, I'd also inspect the same joint on the other side for the same problem.

A skilled welder with the proper equipment could probably do it with minimal heat damage to the surrounding area. A common hacker, like me, would probably set the whole thing on fire.I like the bracket idea.

A decent welder can weld that and that's what you should do. A bracket screwed into it isn't going to hold nearly as well. I weld things all the time in places like that. A skilled guy will keep the temps under control. It's not a big deal and shouldn't cost much to have someone hit that.

Advice needed on separated weld in cabover framing

wa8yxm
Explorer III
Nov 03, 2016
Can it be re-welded: YES
Adding aluminum brackets: NO

Do not mix metals whatever the metal is you are "Upgrading" use the same metal

WHY, aluminum + Steel Plus Salt Plus Water = Failure big time and fast.
j-d
Explorer II
Nov 03, 2016
That'll do it! Could probably use it to lift or tow it...
AndyfromTucson
Explorer
Nov 02, 2016
I found a shop willing to weld the broken joint:

Here is hoping that it holds!
Tom_M1
Explorer
Oct 21, 2016
AndyfromTucson wrote:
If that doesn't pan out I will probably go with j-d's idea of a triangular fish plate and some pop rivets. If I make the fish plate about the thickness of the luan, then when I re-skin I will just not put luan over the fish plate and glue the filon directly to the fish plate. The pop rivet heads will make bulges in the filon, but I can live with that.
There are countersunk pop rivets available. I purchased some from Grainger. You will also need to purchase a countersink bit.
AndyfromTucson
Explorer
Oct 21, 2016
Thanks to everyone for all the great feedback! I guess I will do my due diligence and call a few mobile welders and see if anyone is willing to tackle it. If that doesn't pan out I will probably go with j-d's idea of a triangular fish plate and some pop rivets. If I make the fish plate about the thickness of the luan, then when I re-skin I will just not put luan over the fish plate and glue the filon directly to the fish plate. The pop rivet heads will make bulges in the filon, but I can live with that.

Someone doubted the joint was welded, but it definitely was with small fillet welds on the top and bottom, but not on the sides. To me the welds looked like just barely enough to hold stuff together in the factory while assembling the sidewall, and not beefy enough to be structural, but that is RV construction for you.

Someone else mentioned that screws might crush the tube, tear out, etc. That is my instinct also, but the manufacturer clearly didn't think so: the two horizontal tubes stacked on top of each other in the picture are held together by three 2.5 inch #12 (guessing) screws driven through both tubes from underneath. It looks like the bottom panel of the cabover was assembled in one piece using the square tubing, lifted into place under the sidewall tube framing, and then screwed to the tube framing of the sidewalls. The screws seem to be holding fine, which is surprising.

Someone else mentioned that the same weld on the other side may also be cracked. If I still have some energy left after fixing this side I may open up the weld area on the other side from the inside and take a look.
ken56
Explorer
Oct 21, 2016
Someone mentioned if the weld on the bottom, where it was likely welded in the first place is broken. Its not unusual to have a small gap between pieces for welding expansion purposes. Look closer and confirm that it really is broken. TIG is the best way to repair it if it is broken and a skilled welder is required who has experience in aluminum. It must be squeaky clean to weld. No glue residue as it will just contaminate it and may not flow together well. Yes, I have done some welding and I never could get the hang of welding aluminum. Quite difficult.
j-d
Explorer II
Oct 21, 2016
DrewE wrote:
Welding looks impossible to me without removing the foam etc. from the area...

...I might try a reinforcing plate and some JB-Weld (and mechanical fasteners). If there's any easy way to do so, I'd also inspect the same joint on the other side for the same problem.

Agree. I'd make a generously sized triangular (but square wouldn't hurt, you'll hide it) fish plate. One that allows say four fasteners per edge, inch or a little more apart. Find a POP riveter that'll allow setting steel 3/16" rivets. Might have to be a hydraulic one. They're used on snow machine treads.

"Welded Metal Frame" sounds tough but with the light gauge of the metal, it also means something the coach builder was able to put together fast, perhaps with not-so-skilled labor, and get on with constructing your coach.
Huntindog
Explorer
Oct 21, 2016
Huntindog wrote:
I was thinking of getting some beefy aluminum corner brackets and screwing or bolting them to the framing as an alternative to welding. Anyone have any experience with this?
I don't think that would hold up.
If you want to reskin it with filon, I don't see an easy fix for this.
The aluminum tubing is pretty thin so any bolts, screws etc. will just either strip out, or crush it.
It needs to come apart more to clean up the metal and remove flamables from the area before welding.
If you are willing/able to reskin it with siding, then there are some other methods that could be used.
Huntindog
Explorer
Oct 21, 2016
DP
Huntindog
Explorer
Oct 21, 2016
I believe that is aluminum.
Is the actual weld on the bottom cracked? Hard to tell from the pic.
The open joint that the pic shows clearly, isn't welded at the factory on purpose. A weld there would show thru the Filon as a bump.

That is what I was told by the plant manager at Sabre when I toured the plant.
I think it COULD be welded there, but would need to be ground flush afterwards... This would take away some of the strength.
The factory won't do it this way as the hundreds of joints they weld would all need grinding. Too much labor for them.

That is what I would do, AFTER removing the foam insulation.
Welding is dealing with molten metal. It is way hotter than what it would take to set the unit on fire. I would not even consider welding it without removing all the flamables/meltables from the area. I do not think that ANY good welder would either.