Sagging Belly Pan?

[AirstreamPNW]

Hi there...

I own a 31' 1972 Sovereign, and I've been living in it for almost a year. When I bought it, the previous owners passed the trailer off as a perfectly livable space with no major need for repairs or renovations. They installed a beautiful hardwood floor, wood burning stove, custom furniture in the bedroom, etc. It looked fantastic on the surface. However, now that I've been living in it for some time, I've started to realize how many problems reside below the surface...

I just started on a bathroom renovation project, which revealed the rotting subfloor, which in turn revealed the damaged belly pan at the rear. Upon further investigation of the belly pan damage, I've found myself with a LOT of questions. In all the research I've been doing, it looks like all Airstream belly pans are completely flat. Is this true? If so, then my belly pan is definitely sagging. The whole rear section below the bathroom curves down and is a good 4-5" lower than the rest of the pan. Is this normal? It looks to be part of the design, but every other Sovereign I see in photos seems to have a flat belly pan (though it's hard to tell)... Can any other '72 Sovereign owners let me know whether this is by damage or design? I'm planning on removing the rear section of the belly pan anyway to repair it and remove the old insulation below the floor, but I want to make sure to reinstall it properly. If it's supposed to be flat, I want to make sure to return it to its proper shape (or, rather, buy new flat aluminum sheeting).


Thank you!

[rmkrum]

If its a rear bath, what you are describing could be rear end sag. May need to refurbish and reinforce the frame in the rear...look around the search box using "rear end sag" as a search term.

It is repairable...

[68 TWind]

Might want to post a few pictures.

[air_boy]

I have the same trailer and am working my way through a complete shell-on floor replacement. I have already completed the rear. The bump you are describing is to go around the galv. box that holds the black tank, so it normal. Like others have said, if your noticing a rotten floor there is a good chance that you have rear end separation. Mine did, but my trailer was already gutted so I had no issue further dismantling it to fix it.

I would include some pictures, but mine no longer has the bump. When I removed the black tank i cut out the bump and replaced the cross members in that area to make the belly flush. My intent is to go with a composting toilet or above deck black tank.

Best of luck!

[AirstreamPNW]

Thanks so much for all of this info! It does sound and look like I have some rear end separation happening... Thanks to the other '72 Sovereign owner to assuring me that the black tank bump is normal. I'm going to post some photos here. What do you all think? Rear end separation? And if so, how to go about fixing it? Keep in mind that I live full time in this thing...

(Might have to tilt your head, somehow the photos got flipped...)

Also, I just want to put it out there that if anyone is reading this who has experience doing body work and lives in the Seattle area, I would gladly accept some in person help and guidance!

[air_boy]

Well you definitely have rear ended separation. From your first pic you can see that the C channel (mangled aluminum piece sticking out between the body and frame) and rear hold down plate (rusty steel under the rear hatch) are completely disconnected from the shell. I would suspect the floor back there is disinterested as well.

It is going to be hard to live in and fix. At a minimum, you need to gain access to the area between the skins. Some do this from the outside (search for elephant ears fix) or you can do it from the inside. If your floor is rotted that outside isn’t going to really be a worthwhile option.

Here is a high level approach:

- Remove bathroom
- Remove belly pan, and drop tank.
- Remove inner skins to gain access to bolts. And back side of skin.
- Cut out floor.
- Repair/Replace rotten frame parts
- Replace hold down plate
- replace floor
- Bolt C channel/floor/holding plate/frame sandwich
- Jack up back end of frame and re rivet (lots of solid rivets) shell to C channel.

Here is a picture of what the inside should look like when attached to give you an idea. My C channel is the primed green aluminum.

[AirstreamPNW]

Wow, thanks! This is great info. Daunting... but very helpful. Looks like I might have to find somewhere else to stay for a while. I do have a few questions for you, though.

What exactly is the holding plate doing, and how does it fit into the "C channel/floor/holding plate/frame sandwich" you mentioned? To me, it seems like the C channel, floor and frame would all be sandwiched together, but doesn't the holding plate sit perpendicular to all of this?

You mentioned removing the inner skins to gain access to the bolts, which I totally get, but what do you mean when you say remove the "back side of skin?" Do you mean remove the outer shell panels?

One last thing is... I don't totally understand how all of this remedies the sagging belly pan issue. You mentioned removing the belly pan and dropping the black tank, but then what? Should I replace the belly pan all together with new material? Is removing the black tank totally necessary if I'm already accessing the subfloor from above and removing the belly pan?

Thanks again for all your help. Luckily, my bathroom is already completely gutted except for the skins and floor as I'm in the process of remodeling it anyway. That's how I discovered all of these deeper problems. So hopefully it won't be that much extra work to get everything in order.

[air_boy]

No Problem. It’s a bit tricky to explain so I’ll try my best.

The rear hold down plate is a piece of angle where one side sits on top of the rear cross member below the hatch and goes up behind the plywood, between the c channel and rear skin.

Barts has a pretty good picture of this in post #2 here:

http://www.airforums.com/forums/f477...er-115158.html

His pic also includes some mods to eliminate the piece of aluminum that the bumper trunk cover attached to. This piece funnels water in the back and rots the floor.

You don’t need to remove the outside skins. Just have access to the back side of them to re-rivet.

The floor and c channel is bolted to the frame, therefore you need access to the top and bottom. That’s why I recommended you remove the belly pan and black tank. Maybe you can work around it, but depending on how much floor/frame needs to be repaired it may have to come out.

The belly pan is held up with rivets. If it’s in good shape you can reuse it and just rivet it back up to the frame. Be careful not to drill into the black tank. Many use 3/16 wide flange rivets. If it’s bad just use some new aluminum. .025 3003 or 5052-H32 would be fine.

I would also take a good look at the frame behind the rear axle. If there are any cracks or bulges you’ll need to address it. These frames are susceptible to failure once disconnected from the body. Especially if your axles are shot.

You’ll figure out how it was put together as you pull it apart. Everyone’s situation/constraints are different so you have to find an approach that works for you.

[AirstreamPNW]

Thanks so much! This information is really helpful.