'56 Bubble... floor replacement critical question

[tubestar]

Hi all,
I am new to this forum but paid my dues by restoring a '56 Bubble for the last 2 months making it past shell off and floor installation phase. All this takes place near the beach in Montauk so I am racing against time a little as hurricane season will add (even more) moisture and mold. I am hooked!
I am facing some questions that somehow I cannot get answers to - even within this forum!!! I am very grateful for some help!

1. Subfloor: I am replacing the subfloor with 3/4 inch marine grade plywood, sealed with epoxy. Plywood measurements are 4'x 8'. Looking at the cross-members of my frame I am struggling how to position the panels ... in which pattern are they meant to be bolted (elevator bolts) together. Somehow it seems to offer not enough stability in the front and the rear. As I am using 4 pieces of wood - how should these be placed? two large pieces in the middle and 2 more narrow pieces in the front and back? I prefer to have one full peace of plywood as center piece around the wheel wells - however, looking at most pictures in this forum, plywood joints seem to be running along the center of the frame inbetween the wheel wells leading to two rows of elevator bolts running along the edges of both plywood boards into the same frame outrigger... (is this clear enough?)
2. As my original wood floor was completely rotten I was not able to find the exact dimensions of the rear U channel neither did I see much of a same radius compared to the front. Questions: is the rear c-channel bolted to the last outrigger of the frame or is only the subfloor bolted to the frame in the rear (as it seems in my case) and the u channels are only screwed into the wood. The front clearly shows U channels bolted onto the frame in three different spots
3. it seems there was a layer of something rubbery between the frame and the wheel wells - some kind of insulation/buffer. Any idea what this could be?
4. Within the the U channels, and along the inner outside shell, specifically where the wheel wells are riveted into the shell there is this black insulation material that looks like tar (probably some old sealer / poly)... I haven't found the answer how to get rid of this without using a grinder? Any trick here?
5. As my outside shell is built 56 there was no plasticoat yet. Its pure aluminum exposed to the air. as a result there is quite some oxidation, dirt, salt, bird **** on my outside shell. As I want to start polishing rather soon what is the best cleaner to get rid of dirt and oxidation to prepare for polishing? what do I use? a brush? a sponge? steelwool?
6. Reason for the heavily rotten floor in my trailer must be leaking seams in the upper outside shell. (its a 13 panel front, whaletail back).. what is the beat material and technique to seal the seams (after taking the inner shell off)... Tempro635?
7. I will exchange the insulation with Reflectix. Knowing it required air inbetween the layers to work properly... what is the best way to install this to get optimal results?
Looking forward to some help! Will upload some pictures of my Northeastern project soon!
Tom

[Melody Ranch]

Welcome aboard.

Bubble - Airstream Forums

[tubestar]

Hi Melody! I see you are married to the same airstream model! Mine is a 56 California made cutie.. I bought her without examining the floor through a friend in South Florida.. when we finally got her up Northeast we discovered there was quitre some work to do... so, here we are ; )
I am hoping to get an answer on my u channel and plywood panel question as this is holding up the work right now. Any advice welcome
Best

[rumrunner]

Hi Tom, Robin at Melody Ranch has done more of these than I have but lets see if I can help a bit.
I don't think that cutting the front and rear sheets a bit will hurt as long as it is not excessive. make sure your joints land squarely on a cross member and elevator bolt everything securely.
Put a stainless hex bolt through the floor and c channel on every outrigger. This is what really connects the perimeter of the floor to the frame, the screws holding the c channel to the floor are really just to hold it in position while bolting and not much for structural strength IMO.
You said you were unsure of the dimensions of the c channel for the rear, did you mean the curve or the actual dimensions of the channel?
The curve on these 55/56 era units seems to run really close to a 22" radius. I used this measurement when I laid out the floor for my 55fc and only had to sand a little for a perfect fit
BTW if you intend to add any tanks below the floor now is the time to add supports while welding is easy and accessible
good luck and as always, have fun
tim

[tubestar]

Thank you Rumrunner - that's helpful!
Well, not all joints of my plywood sheets are resting on an outrigger. Not sure if this is a stability issue... I tend to keep it this way believing that the front and rear panel wont have to bear a lot of weight anyway... Will bolt the c-channel to the frame as you mentioned

Now to my most important question - I was not clear enough before: I don't know exactly the position of the rear c-channel (I am using the original c-channels so radius is not the issue). As the shell has been flexing quite a bit since I lifted it off it does not serve as an indication on how far back the c-channel has to be placed. My original measurements indicated 154 inches inside c-channel to inside c-channel. Applying these measurements my rear c-channel is positioned app 3 inches behind the last cross member of the frame (!).. now, thinking about it from a logical standpoint I would think the rear c-channel should be lying right on the last cross member (as it is in the front) and bolted right there. The way it is positioned right now would mean the rear c-channel will be bolted to the frame somewhere along the middle right in the curve...
I hope I can find another 56 bubble floor out there who can specify this rear position for me!!! I would hate to put the new belly pan on and realize later that the c-channel is too far back
Thanks for any advice! Highly appreciated... I hope I can use the upcoming good weather to get the c-channel sorted out and finally apply the belly 5052 0.24...
By the way - I decided to keep the original water tank as I want to keep plumbing to a minimum

[rumrunner]

As far as having joints that don't rest on an outrigger, I wouldn't sweat too much. just cut a piece of floor plywood scrap 6' wide and glue/screw securely to the bottom from the frame out to the floor edge. probably stronger than an unjointed floor. Do make sure the joints rest solidly on a cross member though.
I actually did add 1 outrigger that was not original because I had an unsupported joint like you described right under my fridge. Made me a bit nervous so I fixed it permanently.FWIW I also added short outriggers in the front and rear corner curves similar to the ones found in the later model Airstreams. Adds a lot of stability to the floor in this area.
As far as the fit at the rear I would suggest you PM Melody Ranch as he recently redid the floor in his bubble and could give more direct guidance than I can. In my FC the floor only overlapped the rear cross member by about 1/4 inch or so.The c channel and hold down plate I added bolted directly through the rear cross member.
If you mean that you are planning to reuse the original galvanized fresh water tank I would strongly suggest pressure testing and inspecting it thoroughly. They are notorious for developing pin hole leaks at this age and are pretty small too, only 10 gallons or so. VTS has a very good poly replacement that should install easily and double your fresh water capacity.
Hope this helps
tim