The banana skins are pretty maleable, not 2024, so you can hammer them out easily. I got tired of the PO's dents a few I put in myself, so I thought I'd take a shot at "fixing" them.
I'm no body worker, so I lack the panel hammer with the curved face and the sandbags that would allow me to get a smoother finish, but I don't think you're going to get all the small rock dings out anyway, so a few hammer marks are acceptable to me, compared to the big dents. I just cut a couple pieces of 2X4 to approximate the final curve and took the big dents out with those, then used the plastic and ballpeen hammers against the steel table saw top to get the smaller dings. You have to be careful as you do this and stop early, or it gets worse with hammer dings, not better.
The finished product isn't perfect. I'll post a photo of the installed skin once it gets buffed a little to see if it's really an acceptable repair (tune in next week).
Ohhh, that looks nice! And not all that terribly difficult, huh? I'll bet that ... oh, well, looks like there's another one for my list. First, finish the MG. Then build Maria's deck. Then renovate the women's room on the park. Then fix the truck. Ok, so this is going to have to be fifth on the list of Big Things To Do.
Lynnnnnnnnnnnnnnnn
Here's the rear street side reinstalled and buffed up a little. I was surprised to find that the clear coat was almost perfectly intact (I guess it's mostly out of the sun down there), so I took it off with Bix. My first polishing pass is with a cheapie polisher from Harbor Freight using cloth wheels you can get at truck stops. The yellow one is medium stiff, then I go to a white one, which is relatively soft--the red is too stiff. I start with a semi-liquid green paste in in a squeeze tube called emery polish. Once I get to where I can see whether or not I have bad corrosion (none on this banana, Yes!), I start using the wool bonnets and the Nuvite polish.
The skin came out OK. I put in the red lines so you could see where I made some tool marks, slight vertical bends in the skin just below the lines--I should have relieved the edges of the shaped 2x4 block! The sharp edges are what did the damage. If I had radiused the edges about 3/8", you'd never see any tool marks. Live and learn. However, the banana skin passes the 8' test, no sweat, and actually, I think it passes the banana skin test with flying colors!
This particular banana skin polished up very quickly, compared to the side skin above it. It may have something to do with the lack of corrosion or the alloy--very soft compared to the side skins.
I applied Vulkem to the seam so that rain water running down the side wouldn't automatically be channeled into the inside of the banana skin. The seam is hidden under the trim belt, so it was a quick and dirty application.
You can most likely get out alot of the small dings using a leather bag filled with #9 lead shot as your backup and the rounded end of a wooden broomstick used as a punch to GENTLY work out the dings. This works pretty good for me with soft or annealed aluminum. We take bird strikes on the nosecones of our research pods every now an then, and this is how I work those dents out.
Rant: is it possible to ever take off a piece of skin and just do what you originally intended? As you can see, the scope of this fix has expanded to fit the time available...
Here's the scoop on the hidden spare tire area. Sorry about the quality of the photo, but the reflection this morning is blinding the camera, too. Oooh, but the shine...
OK, I've done a quick frame drawing and tried to provide some visual sense of this with the photo. Yes, Virginia, there is an alcove between the forward frame and tongue channels ,which is prepped for a tire alcove. The top of this area, up against the floor, is protected by a sheet of what appears to be 1/16" plastic that has a layer of fiberglass between it and the floor. All this is squeezed by the frame members, so although it's smooth, it's something of a slight dome, thicker out in the center and squeezed to practically zero as it goes between the frame and the floor. Very compromised as far as insulating qualities, to be sure. As a matter of fact, the entire front end seems very compromised as far as insulation goes.
In the outboard compartments there was the standard stapled fiberglass, which I'll replace with solide foam. The fiberglass was in pretty good condition, except in one compartment, where it has fallen.
There was a mouse house in that dark triangular area. The only path I could discern for a mouse getting in there was through the frame from the rear. It had accumulated a hoard of candy, bird feed (from a PO), yellow fiberglass (Airstream uses red, so I need to find where the heck I've used yellow!) and a ton of those little blue DeCon poison rods. A ton. No skin or bones of mouse were found. I think I'll plug up the frame channel when I put the insulation in.
Note the threaded nuts in the cross member. I believe they're for installing the spare tire trapeze. BTW, the circle in the drawing is 30" in diameter, about 1/2" wider than the tires I'm using.
You can't do one of these projects without something totally unexpected bitting you. In this case it was hidden rivets in the lower aft corner of both of the forward banana skins. This photo is of the curb side skin, back near the door. You can see that the piece of skin that is hanging down had to be unfastened in order to even see the rivet (the rivet hidden under that skin). The really bad part of this is that the covering skin was the extension of the side skin from above, not some piece of trim that only curved up to the trim belt. What a total pain, and unnecessary.
The other problem was the skin between the tongue frame. I can hardly conceive of how it was installed--it had to be in place before the blind rivets were driven in the skin below the front window or, more likely, was in place and the shell was lowered onto the floor/frame and covered this piece up. There was absolutely no way to get the belly pan down without significantly bending this piece, so I removed it ever so daintily and wil replace with a skin that is external and stops under the trim belt. It's purpose is to close the area between the tongue frame and to wrap under the belly skin at the leading edge, preventing the belly skin from being a water scoop.. This can be accomplished fairly easily, since the trim belt can conceal the top edge of this small new piece of skin.
Let me start by saying that Andy has warned all of us, and me in particular, that Airstream tried using solid foam insultation but found that it is too stiff and eventually crumbles due to flexing of the frame. One potential solution is to use the spray foam that remains flexible, in order to provide some give at the edges and protect the large sheets. In short, consider carefully before you insulate this way.
As in my axle replacement project, I screwed and glued the sheets of foam to the floor. Due to the "sag" of the insulated area in the center, I installed that piece using 1" thick pieces of foam only around the edges, allowing the center to be offset from the sag. BTW, the covering that I thought was "plastic" turned out to be aluminum painted gray, probably .025.
You can see the cirlce on this layer that shows the size of a tire, with about 1.5" of room around the edge.
After installing two layers of foam, 1-1/2" and 1", glued together and to the floor and screwed in using little squares of aluminum for washers and 3" dry wall screws, I used the spray foam as an edge seal and adhesive. I'm pretty confident that it will remain in place. One thing I am particularly careful about is to provide a path for water to escape--the insulation does not touch the banana skins. Any water that happens to run down the side will continue onto the belly skin and drain out the many joints allong its edge. The insulation does not touch the belly skin, either. It's easy to trim the sheets and spray foam with a hacksaw blade.
I also added two layers of 1" foam in the stair recess (not shown). The only area that isn't well insulated is a small compartment just forward of the stair recess--I can't even get my hand in there. I guess I could have stuffed it with fiberglass, but I couldn't see how to restrain it up against the floor to keep it from getting wet.
I have to say that although I'm definitely not going to win any classic car restoration prizes with my bodywork, I'm quite happy with the way the banana skins turned out. They're obviously beat up, but they're in an area where that's to be expected. They almost look hand-crafted in the original, which seems to suit my expectation for a Vintage Airstream. Polishing is also working out OK, but many of those black-hearted little dings are going to remain that way for now.
Here's the "before" from the first post
And here's the "after." The photo on the left shows the skin after it has been buffed with very fine scotch brite, and on the right after two passes with F9 Nuvite.
Oops, the skin on the right really doesn't look that good in person. Lots of work to do on polishing the shell.
All that's left is to put in the skin between the tongue frame and the trim belts and Mbuti's ready to roll to the RMVAC Rally!
what kind of rivets are you going to use to reattach the belly segments at the corners? mine look as bad, if not worse than yours, and it's on my list. i've used olympics on some non-structural parts of the trade wind, but the rivets around the belt line seem pretty significant, structure-wise.
Actually, no. Not much stress in from the lower belt line down through the banana skins and belly pan. The semi-moncoque structure ends at the floor level.
Yes, there is stress on the banana skin from the flexure of the frame. The belly skin is under stress because it's a horizontal sheet that flexes and isn't tightly fastened to the frame, not like the skin is tight to the ribs. But it's a local stress. If the belly skin fell off, it would have zero impact on the structural integrity of the trailer.
Having said all that, the movement (twist, bend) of the frame puts stress on the banana skins and belly skin. I did not replace the corner rivets--no real requirement. The aft end of the forward banana skins slips in between two other skins and overlaps at least an inch. If you wanted to secure the absolute tail end of these skins, you can rivet from the exterior all the way through--you don't need any hidden rivets inside. Just use regular aluminum pop rivets in the places that were original. If the 1/8th holes have gotten a little elongated, drill out to 5/32. I had to replace 20% of the original 1/8th rivets with 5/3nds. Happy to do so.
gotcha. on my '59, it doesn't have those rounded front pieces, the belly just stretched up to meet the floor. when i was replacing the floor, and skins, i used bucked rivets everywhere, for strength, and ease really. everything was exposed. heck, it still is! no interior walls even now!
but on the 64, i'd like to replace the belly WITHOUT ditching the whole interior. for the sides, i wanted to use olympic rivets, since they are exposed. behind the front trim piece, i guess it would be safe to use the sealed blind rivets. they have a solid end, and when applied, seal the hole. i've used these on everything on the exterior so far (tail lights, running lights, serial plates, etc). here's my source:
forgot about this thread in all the camping we did thi syear (and other mor epressing repairs, obviously!) a similar repair to my lower skins is on the agenda this winter, though. one question i forgot to ask about the dents. do you think running them through an english wheel would help? i have access to one, but have never used it. i hear the learning curve on it is pretty steep. i would be concerned that with all teh banging and thumping that the aluminum would stretch and never return to near it's original shape.
having said that, your pics look great! whenever i get around to this, i'll have to post pics of it here.
rather than the english wheel, I'd use lead shot bags from the autobody industry, or take a little more care in rounding all the edges of thecurved 2x4 block. Either way you'll get a smoother appearance. I think the wheel would take out the tiny gravel dings, but at pretty high risk of totally deforming the piece.
i'll try that idea. i'm just a little concerned about leaving little ping marks in the aluminum. dunno when i'll get to it, but i'll be sure to post pics here.
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