Separated undercarriage and rippling trim

[BruceClan]

I’m looking at a gutted 1978 Airstream Sovereign(?). It’s 31’ but I’m unsure of the model. There are two things that are bugging me about it but I’m not sure which of them are important. First, in the rear the metal sheets that make up the outer shell have separated from the undercarriage in two places (see pics). It’s a sizable gap and the metal sheeting looks abused. Is that a major issue or can we just hammer that back out and reattach easily? Second, all along that same seam which wraps all the way around the trailer the lower portion is not flush with the upper portion. Instead it ripples between the screws that attach them. (see pics). The trim was removed when they gutted it, but they kept the trim. As it is, rain water runs down the shell and into those gaps. Where is that water going? should those two pieces be flush along the length? Can we flatten it out and seal it? Does the trim usually prevent water from getting into that space?
I’ve read about sagging in the rear; is this a symptom of that?

[HowieE]

Looks like the body has separated from the frame and floor section. The rivets have sheared off.
If you can look at the inner skin where it is riveted to the C channel I suspect you will see all the rivets have sheared off.

This is the result of the Hammering of going down the road. Possible causes, too heavy WD bars, very heavy truck suspension, poor shocks on the tow vehicle. In any case a big job to fix.

Mine failed and I had to re rivet both inside and outside from the door all the way around to the same distance back on the other side. They used to put a plate inside the outer skin and use it as a place to put extra rivets in the outer skin and secure it to the floor inside the c channel.

[Belegedhel]

Welcome to the Forums!

Yes, you are looking at evidence of the classic case of rear-end separation. The wood floor that should be sandwiched between the shell and the frame in the back has rotted away, allowing the frame and shell to move independently of one another. At the same time, the rear cross members and other frmae components have likely begun to disintegrate as well. If you step up on the bumper and bounce a litlle, you will se these gaps opening up as the frame flexes without support from the shell.

If the bathroom is in the rear, look underneath at the framework that is supposed to be supporting the black tank. The whole assembly is likely to be drooping and fixing to fall out.

The fix? Replace or patch the rear-most sheet of plywood subfloor, rebuild/repair the frame, and then mate the whole happy sandwich back together. It is major surgery, and it is a very typical repair required of trailers of this genre that have been sitting unmaintained for the last 20 years.

Now, some of those pictures just show a gap between the upper shell and the banana wraps. These gaps would be covered by the trim piece if it were there. The gap is probably getting exaggerated because the rear frame is flopping around loose.

So no, there is no easy fix for this problem. It will be a labor intensive repair. You may as well do a complete floor replacement while you are at it, because there are likely to be rotten spots in it all along the perimeter of the trailer. As I say too oftern, trailers this old pretty much all need a shell-off, if they haven't already had one. This is yet another aborted project. The current owner probably thought they were going to splash around some paint and lay some vinyl flooring and would be traveling in style. Instead, the enormity of the project overwhelmed them, and they are ejecting. Don't buy someone else's failed restoration unless you really know what you are up against.

good luck!

[J. Morgan]

If a person is handy and can weld a little, it is a pretty quick fix once the interior is stripped out.

[BruceClan]

Thanks for the helpful answers. We are hoping to completely strip an Airstream and rebuild with mold-resistant materials for health reasons. Would taking out the floor of an Airstream result in this same scenario where the subfloor and the frame are separated and have to be sandwiched back together?

[J. Morgan]

Originally Posted by BruceClan

Thanks for the helpful answers. We are hoping to completely strip an Airstream and rebuild with mold-resistant materials for health reasons. Would taking out the floor of an Airstream result in this same scenario where the subfloor and the frame are separated and have to be sandwiched back together?

The plywood fits between the frame and the body shell so if you took off all the plywood at once it would settle. This means that either you have to pull the shell off the frame or repair/replace the floor one piece at a time.

[DavidsonOverlander]

Originally Posted by J. Morgan

The plywood fits between the frame and the body shell so if you took off all the plywood at once it would settle. This means that either you have to pull the shell off the frame or repair/replace the floor one piece at a time.

A shell-on floor replacement will look something like this. We later decided to remove all of the interior skins to re-insulate, but this photo was taken before we made that decision. You can see in the lower right where I've left a small piece of the floor in the C-channel to maintain the connection between frame and shell. Starting from the back I removed the old floor, repaired and painted the frame and installed the new floor. The back piece shows a seam in the middle, but I think I could have installed it in one piece like I did for the rest of the floor. I had to repair or replace about 3/4 of the outriggers.



I used West System Epoxy to coat the outside foot or so of the plywood (top and bottom) to help protect against moisture, and used epoxy to join all pieces.

[BruceClan]

Thanks for the floor replacement info. How thick is the plywood? Do you think it would be possible to replace it with a combination of aluminum diamond plate and a buffer like foam or rubber?

[DavidsonOverlander]

Originally Posted by BruceClan

Thanks for the floor replacement info. How thick is the plywood? Do you think it would be possible to replace it with a combination of aluminum diamond plate and a buffer like foam or rubber?

The plywood I used was 3/4". Personally I wouldn't use anything else, although there has been talk of using some sort of plastic and I think some Argosys were made with aluminum floors. It's not something I'd want to be experimenting with because if it goes wrong you pretty much have to gut the trailer again to replace it.

[Foiled Again]

Originally Posted by BruceClan

Thanks for the floor replacement info. How thick is the plywood? Do you think it would be possible to replace it with a combination of aluminum diamond plate and a buffer like foam or rubber?

Bruce, your questions show me that you are interested in doing it right ... and also being innovative in selecting materials/methods. Unfortunately there are more than a few people who are flippers and do just enough to make a "polished turd" that can be sold to a novice owner at an inflated price. The pictures posted above show a well executed frame on replacement. Airstreams have a frame, but it is a very light and somewhat flexible one.
(Spellcheck isn't helping me with monocoque - but it's the same concept used in building airplanes.) Anyhoo.. the idea is that the floor and body and frame have to function as one unit that is both strong and flexible. Aluminum diamond plate is being used in some areas of some newer Airstreams... my Eddie Bauer has it under the bed in the garage and I hate it, because if water gets under it I could get rot and not know it. Punched a few holes thru it, and use a moisture meter periodically to check. Anyway, if I were looking for a restored Airstream the mere presence of diamond plate would make me leery of what it might be hiding.

The plywood that is currently used is tongue and groove - so that the sections act like a one piece floor - and each seam is normally on top of a cross member or has splicers underneath to reinforce the joint.

If memory serves there is some kind of aluminum plank system that could be used, but shrinking and expansion might be an issue, plus COLD on the feet in fall and winter. And expensive! Coosa board is a marine product that is highly regarded... and highly priced, but this isn't a job you ever want to do over!

Read a lot.

Meet others who have done multiple restorations even if it takes a 200 mile drive... the mistakes you avoid will reward you hugely.

Best wishes, and get a tetanus shot!

Paula