Bottom rear skin separated and leak

[mariusg78]

Hi all,

What do you recommend to do with this issue (see picture). Looks like previous owner backed into something and caused the bottom skin to detach from rear frame. Living in the northwest we get tons of rain and when I removed the sub-floor, there was a lake of water underneath. I was thinking of trying to weld the inside skin back to the chassis. Another fix I was thinking was to try to reattach the bottom skin by bolting it back to the rear chassis, then sealing with Vulkem. Any suggestions are appreciated. Thanks!

[BIGED52]

This issue is not caused by backing into something! It is most likely a sagging frame from the axles to the rear bumper. Most likely cause is frame damage (bent/broken) due to rust or excess weight on rear of trailer frame. usually caused by water damage to the rear sub floor that allows the shell to separate from the floor/frame. This can be fixed. Ed

[wahoonc]

Search the forum for Rear End Separation...

It is in my opinion a design flaw from Airstream. There are a variety of ways to eliminate it, after you fix the damage. I am making a custom flashing to lead the water off the bumper.

Aaron

[Lumatic]

Structural strength in an AS is achieved by the sides being bolted to the floor and the floor bolted to the frame. When the link fails the cantelever effect of the rear frame causes separation. If you are going to tow this trailer you will have to replace the subfloor in the correct position under the sidewall and above the frame. To do this you may need to jack up the trailer body or pull down the frame. You do not want to seal the belly pan which will collect water and cause more rust.

[mariusg78]

Thanks for the suggestions. My first priority is to stop the leak you see in the picture coming from the gaping hole on the back. Once I have sealed this, then I will attack the rust issues. The large major rails have rust, but are not deteriorated too bad. The two posts you see in the middle have fairly bad corrosion. I might remove them or sister on a new set of posts after of course I clean and seal off the corrosion.
I will post pics on how this goes. Depending on the weather, of course!

[Lumatic]

I just snapped to the bolt holes on the rear bumper. The holes appear to be close to the belly pan separation. The bumper is not designed to be weight bearing. I'll bet you a dollar the weight of whatever the bumper was carrying was the major cause of the problem.

The bigger problem is putting Humpty back together again so the walls are attached to the floor and the floor to the frame.

[mariusg78]

OK so I was able to reattach the bottom skin to the frame. I drilled smaller bolts through the bottom and through the frame. Threw a locking washer and nut on the top, then sealed with Tempro (Vulkem). This selaed it up real nice (See pics below). Heavy northwest downpour confirmed the seal, but was getting the dreaded rear storage door leak. I removed all the rear trim and found out that AS put the panels backwards (in my opinion, but maybe was designed this way). Anyway, I sealed everything with Tempro (Vulkem) and reattached with new rivets (which I dipped in sealer before attaching). Next rain will tell me how well the seal went.

[Colin H]

Originally Posted by mariusg78

OK so I was able to reattach the bottom skin to the frame. I drilled smaller bolts through the bottom and through the frame. Threw a locking washer and nut on the top, then sealed with Tempro (Vulkem). This selaed it up real nice (See pics below). Heavy northwest downpour confirmed the seal, but was getting the dreaded rear storage door leak. I removed all the rear trim and found out that AS put the panels backwards (in my opinion, but maybe was designed this way). Anyway, I sealed everything with Tempro (Vulkem) and reattached with new rivets (which I dipped in sealer before attaching). Next rain will tell me how well the seal went.

This was a waste of time, you you need to drop the bellypan & remove the interior lower wall panels in order to properly install the the new floor sections. Sealing the bottom of the bellypan is just creating a bathtub.
Colin

[mariusg78]

It was a bathtub before the seal due to the draining of all rain water through the back compartment which in turn caused a ton of rust. I have seen many options of redoing the subfloor without removing the belly pan. Either way, I have no way of storing the pan dry or the capability of jacking the trailer up to take the pan off. So, I'm doing the best I can with what I have to work with. My main plan was to keep water from continuing to pool in the AS. If you look at my first pictures, you can see the huge gap in the back of the unit that I had to seal.
If I didn't seal that part, then water would have continued to pool up.

[mccrosti]

I am in the middle of a rear bath repair. It was initially repaired incorrectly by the PO. They used threaded rod and what seems to be 10 tubes of caulk to facilitate the repair. I don't know when this was done, many years ago I would assume. When disassembled you see just how much damage there is. The backing plate and part of the c channel are non existent due to dissimilar metals and water incursion. The floor is completely rotted in places. Most nefarious is that you could not tell exactly how bad it was until the interior skins were removed. If you have the time skills and inclination, do the job right, otherwise you're just passing the problem along to someone else.

[Colin H]

Originally Posted by mariusg78

It was a bathtub before the seal due to the draining of all rain water through the back compartment which in turn caused a ton of rust. I have seen many options of redoing the subfloor without removing the belly pan. Either way, I have no way of storing the pan dry or the capability of jacking the trailer up to take the pan off. So, I'm doing the best I can with what I have to work with. My main plan was to keep water from continuing to pool in the AS. If you look at my first pictures, you can see the huge gap in the back of the unit that I had to seal.
If I didn't seal that part, then water would have continued to pool up.

There is no way to properly install the floor without removing the bellypan & the inside lower wall sections in this area. You have to have access to both sides in order to install bolts & nuts. Every other way is just a bandaid, & will fail. This doesn't mean that you must remove the whole thing, just the rear portion of the bellypan & let it hang until you've completed the floor replacement in that area.
Colin

[Panama Red]

Colin is 100% correct. You can't do this correctly without removing the belly pan and the interior lower skins in the area you are replacing the flooring.
Trust me, I just did the same thing on my 74, and based on what I've read in this forum, I bet Colin has done it more times than you and I ever will...
-Red

[mariusg78]

I completely understand the floor thing. I was just posting an update on the seal on the back and the back rear. I understand for stability, structure, etc. that it is important to have the floor attached to the sides and bolted on. I have already removed the interior lower panels and am in the process of removing the old bolts out. I appreciate the help with this but this was mostly based on the leak from the silly back compartment.
I know many folks had issues and posted about the leak in the rear compartment and C channel, so I just wanted to put an update on the sealing process.
Maybe this has been a "waste of my time", but this is how I learn.

[shadeemry]

I put drain plugs , similar they use on jeeps into my belly pans can get them at lowes for about 2 bucks.

[perryg114]

The pan won't get full of water if you separate that storage compartment from the back of the trailer. This whole design with the funnel plate and extending the belly skin out to also be the bottom of the storage compartment was a piss poor design from day one.

Here is what I did. I need to post some final picture of the storage box put back together.

http://www.airforums.com/forums/f476...fun-91686.html

I tried to add some photos below but they don't want to post.











Perry

[ventport]

If you do not remove the inside lower skins you cannot see what shape the rear hold down plate is in. I have done 4 of these and every one had to have the rear hold down plate replaced. It is the angled plate that is riveted to the lower center of the back shell, directly under the rear window. You will see a bunch of rivets in the aluminum in the center just above the storage compartment. The other part of the angle is riveted to the frame, and connects the body to the frame. If this is rusted through, everything you are doing is just a waste of time.

[perryg114]

I have been told that the hold down plate is not use on the new trailers. I wonder how they get a good solid connection back there with no hold down plate. I think it or something like it needs to be there.

Perry