Inexplicable bumper design

[drm101]

I also had there rear rot issue. The rear 6" of the wood was completely rotted. I dropped the black water tank, repaired the rusty crossmember holding the tank in, had a new blackwater pan made of galvanized steel, cut off the wood with a skil saw, dug out all the rotted wood, slipped in new marine grade plywood and drilled out all the screws and replaced them with 3/8 in. stainless bolts. I made steel plates with 3/8 in bolts to go over the plywood gaps and insure a stable floor. I then used a PPL product (polyeurethane from Home Depot) and sealed the entire rear seam and the entire piece of trim. That was in 2003 and it has not been wet since. My trailer sits outside (unfortunately) all year. It's much easier to get in there and fix this stuff with the black water tank removed. You can also have a local heating and cooling guy whip you up watever sheetmetal you need. they even made me a new sheetmetal piece for my rear bumper compartment that looks better than factory. I also painted the frame in there with POR15. It's good for another 40 years.

[tkasten]

drm101 - thanks for your experience and fix. Sounds like your good for another 40 years. I pulled our 65 Safari out of the poll barn last week and went at the bumper problem. I used builders Solar Seal to caulk the seams deep inside the seam of the bumper all the way into the floor. Then used vulkem on top of the the trim channel and all the riverts. I gave it a major hose test under high pressure and so far no water inside. This really was a poor design that could have been easily fixed with a piece of 90% angle. If the caulk holds for a few years great. If not I will have to consider a complete rebuild of the rear end as you have done....nice to hear from another Michigander.......Tim

[drm101]

Just another tidbit. There is a bulletin from Airstream regarding Frame Seperation that details replacing the rear channel bolts. It gives some good pics of how it goes together and how to repair it. One thing that I had to do was to cut a two by three squarein the skin above the frame to get at the bolts there. I used standard aluminum flashing and sealed rivits to cover the holes. olympic rivits would have been better, but I was a novice then and didn't have them or know where to get them. If the wood is rotted, chances are good the bolts are rusted too and it's a good idea to fix it all at once and be done with it.
Regards,
Dean
Marshalls Corner Shop

[Robbie R.]

I am going to try to seal my bumper area soon.

I have no water showing at all now or rot at all (thank goodness for marine ply wood) but did have some slight water on the edge until I put plastic over the bumper for the winter.

What a pain that was having to keep it on all winter............

Does anyone know if the large channel trim is plastic and flexible ?

I know the plastic strip inside the trim is plastic because I took it off last year to caulk around screws but the main channel that holds this has me puzzled.........it looks like aluminum and I am wondering how to remove it without kinking it ?

Or can I just raise it up off the seam to seal ?

Also, my screws heads are rusty, any idea of an easy way to get them out ?

Robbie R.

[Zeppelinium]

the trim is aluminum. if you still have the plastic blue strip inside it, you have to remove the plastic in order to see the pop rivets that hold the aluminum trim in place. you will need to take the rivets out for quite a ways around the side and forward, maybe 4 feet or so, in order to lift the trim up out of the way when you caulk.

getting the rusty screws out requires a good phillips screw driver, like Sears. don't use the import models, even if they have a strong tip--they have too shallow an angle and will bugger the screw head. then it takes a dose of luck. if you don't have luck, make sure you have a good 1/8 bit to drill them out with...

Zep

[Robbie R.]

Thanks a lot for the reply. That helps me a lot and makes me feel like I have a good chance of curing this problem.

I plan to tackle this soon.

Robbie R.

[Frank's Trailer Works]

There is more than one design flaw in the rear of these early 70 units. In the rear is a steel plate that attaches the shell to the frame very solidly.

You can see it in the bottom left corner of this photo...

once you remove the belt line you will begin to see how this flaw is eating up the skin.

and sending chunks of both aluminum and iron oxide out of the seam between the shell and the frame.

And then when you lift the steel angle off the bolts you will find an aluminum plate that makes up part of the bumper hatch...

And this is what remains. No one must have known that aluminum, steel, water, and a slight electric current are not a very good combination.

[Birdwell57]

Originally Posted by 62overlander

And this is what remains. No one must have known that aluminum, steel, water, and a slight electric current are not a very good combination.

Is there a way to insulate the aluminum from the steel?


This is what was left of my floor.



I'm pretty sure it was because of the bumper problem. The aluminum and the steel angle in the back were also FUBAR, and have been remade. A small strip of skin between the bumper and rear access door also had to be replaced. I'm getting ready to reconnect the shell, and would like to keep this from happening again. How about drilling or punching some holes in the tain't (it ain't shell, and it ain't bumper)?

[ventport]

Why not make the re-enforcement out of aluminum instead of steel?

[Birdwell57]

Originally Posted by ventport

Why not make the re-enforcement out of aluminum instead of steel?

Sooner or later, the aluminum has to touch iron, Rear angle to frame, channel to outriggers, etc.. I was thinking about some sort of insulation for any of these spots.

[Zeppelinium]

Originally Posted by Birdwell57

Sooner or later, the aluminum has to touch iron, Rear angle to frame, channel to outriggers, etc.. I was thinking about some sort of insulation for any of these spots.

I don't know how you'd avoid the conductivity of the fasteners, either rivets or screws. Maybe using aluminum rivets would concentrate the corrosion at the rivet-to-frame point and one could periodically replace the rivets? Given that the aluminum sheet is otherwise insulated from the frame, of course.

Zep

[Birdwell57]

Originally Posted by Zeppelinium

I don't know how you'd avoid the conductivity of the fasteners, either rivets or screws. Maybe using aluminum rivets would concentrate the corrosion at the rivet-to-frame point and one could periodically replace the rivets? Given that the aluminum sheet is otherwise insulated from the frame, of course.

Zep

Didn't even cross my mind. So, it might be better not to try and insulate, which would then concentrate the conductivity to a smaller area around the fasteners. It's back to giving the water that gets in some place to go, and trying to keep water out. What about holes in the tain't, or would that cause a whole other problem with water draining into the waste water tanks pan?

[Aerowood]

Primer and lots of sealant on all mating surfaces is the key. Install all hardware wet with sealant. Keep the moisture out and the bare surfaces of dissimular metals fron contacting each other.

[Stumpjumper]

Water is a problem at the rear bumper area for sure. I am doing a 79 Argosy and caught the problem before too much damage, but how to fix? Some good ideas here. However, even if one seals the top edge successfully, where is the water that gets into the bumper storage area supposed to go? Just flow on down into the belly pan? I'm thinking of drilling some holes in the bottom of the storage area?

[Zeppelinium]

Originally Posted by Stumpjumper

... where is the water that gets into the bumper storage area supposed to go? Just flow on down into the belly pan? I'm thinking of drilling some holes in the bottom of the storage area?

Yes, make sure the storage area is "leaky."

[Bowmans]

Stumpjumper,
We have a 1979 also. We drilled holes in the bottom of the storage area to drain. We also sealed the space between the outer alum wall and top of the trunk area but still had a leak. We found that inside the back trunk, where the back frame meets the top (not the lid but the permanent metal "roof" of the trunk), water was running insde there. We ran a bead of vulkem around that and it has ben fine since then. A trick is to get a small mirror and lay in the trunk. It helps to see where the bead of vulkem needs to go.

[KYAirstream]

Originally Posted by vhord

I am thinking of bending a sheet of aluminum at a 90 deg. angle to slid up under the outer skin and under the hose carrier lid hinge. Here is a crude drawing which I hope will explain what I am trying to say.

Attachment 56008

Any ideas on this?

Sorry for digging up an old thread, so if this is better off in a new thread please let me know. Was searching for threads on using a drip edge at the rear bumper and a Google search actually brought me to this one. Was just wondering if many have implemented a drip edge of some kind along the rear bumper as opposed to maintaining sealant along that connection?

I was also wondering if it is necessary to run bolts through the floor when attaching the shell to the frame. Any reason why the floor couldn't have a small notch where each bolt passes through? Doing this may be of no benefit though since access below may still required to tighten the bolts, unless the outer frame utilizes some sort of welded nut strips?

Lastly, has anyone experimented with using a strip of composite material (eg deck board or fascia) along the walls, and then in filling the remainder with plywood? Or would this affect the integrity of the shell/frame connection compared to using full sheets of plywood fastened throughout?

Sorry for so many questions. Just trying to get a sense of the best way to tackle this in the future.

[HiJoeSilver]

Was searching for threads on using a drip edge at the rear bumper and a Google search actually brought me to this one. Was just wondering if many have implemented a drip edge of some kind along the rear bumper as opposed to maintaining sealant along that connection?
Best way is to get rid of the piece of aluminum that runs from below the floor and shell out onto the bumper to support the hinge. Are you taking the shell off, have interior skins removed so you can get to bolts? If so either don't put it back when you put the shell back down, or remove the bolts in the back that pass through it and pull it out. Then put a piece or aluminum up behind the outer skin and c channel, like you were putting a side wrap behind the skins on the sides. Have the aluminum stick down straight then bend it forward under the trailer. It'll block any water from reaching the wood. On top where the frame comes out put a piece in behind the skin as well and bend out along the top of the frame rail do it deflects water away from the wood as well. Seal well.

I was also wondering if it is necessary to run bolts through the floor when attaching the shell to the frame. Any reason why the floor couldn't have a small notch where each bolt passes through? Doing this may be of no benefit though since access below may still required to tighten the bolts, unless the outer frame utilizes some sort of welded nut strips?
Yes bolts need to go through the floor . Without the wood there, when you torque the bolts it would crush the c channel without wood in there for support. I used bolts that have armor coating I got from McMaster Carr. It's a hard coating of aluminum and zinc that helps prevent corrosion. I think they'll be good as new in 30 years. Less worry about galvanic corrosion using stainless fasteners. You can also spray a bunch of galvanizing spray paint on each bolt and in the hole so the zinc corrodes instead of the bolts. You need access to both sides you use bolts and nuts. And washers recommended on each side .

Lastly, has anyone experimented with using a strip of composite material (eg deck board or fascia) along the walls, and then in filling the remainder with plywood? Or would this affect the integrity of the shell/frame connection compared to using full sheets of plywood fastened throughout?
I think this would weaken the whole structure overall.

[KYAirstream]

Originally Posted by HiJoeSilver

Best way is to get rid of the piece of aluminum that runs from below the floor and shell out onto the bumper to support the hinge. Are you taking the shell off, have interior skins removed so you can get to bolts? If so either don't put it back when you put the shell back down, or remove the bolts in the back that pass through it and pull it out. Then put a piece or aluminum up behind the outer skin and c channel, like you were putting a side wrap behind the skins on the sides. Have the aluminum stick down straight then bend it forward under the trailer. It'll block any water from reaching the wood. On top where the frame comes out put a piece in behind the skin as well and bend out along the top of the frame rail do it deflects water away from the wood as well. Seal well.
l.

Great idea. So if I'm understanding correctly, you would have two L-shaped pieces of aluminum back to back, with the long side of the L's up against the outer skin. The L folded forward toward the front of the trailer would be longer so it terminates under the flooring. The L going out toward the bumper would sit similar to the current aluminum on top of the bumper, but would be bend at a right angle along the inside of the outer skins. Seems like a relatively each fix, with the latter being something Airstream could have done easily with the current piece of aluminum.

[KYAirstream]

As far as the subfloor, I've read some posts that say not to use tongue and groove sheets, but I haven't seen an explanation as to why? If the tongue and groove land on a cross member, what would the problem be?

I have a friend that recently built a tiny house on a trailer. He used Advantech tongue and groove for his subfloor/floor and it turned out great. He stained it and applied several coats of poly. It looks great as is (almost looks like cork) and the seams are barely noticeable. I'm not doing a shell off, but thought if I ever were to this might be a great way to go.