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LifeIsRiveting · 01-20-2016, 10:43 AM

I have read nearly all the major full-monte threads posted in the sticky (not just looking at the pictures) but one question still comes to mind...

While coming up with a plan for a shell-off I sometimes wonder: Is it possible/advantageous to keep the C-channel attached to the shell and just remove all the fasteners that hold the C-channel to the subfloor/outriggers? It seems that this would help the shell hold its shape better and avoid hole misalignment down the road. Perhaps even save some time, effort, and rivets. Of course, if there is extensive corrosion or damage to the C-channel then it will obviously need to be removed for proper repair at some point. Also, I understand that my 1976 has the "double C-channel" that wraps around the edge of the sub floor. I think this method is still possible but I would have to support the shell using gantries, then cut out the sub floor before lift off.

Now I'm not looking to save time and cut corners, I'm just interested in doing things the "right" way. So do you think leaving the C-channel attached to the skin is the "right" way? Are there some little (or big) points that I am missing?

Thanks!

-Jared

Wabbiteer · 01-20-2016, 11:43 AM

Double-C-Channel will have to be loose to slip over the new flooring as it clips over the edge of flooring, rides above the outriggers AND THEN captures the end stubs of the ribs. There are plenty of rivet holes that show the assemblies original alignment to the ribs, and the outrigger bolt bores are likely oversized.

The only single-c-channels would be found at the endcaps and they stay on the shell during lift, refurb and landing. Problems may happen around the water heater on the rear endcap since the c-channel is cut away there that can complicate 'stretching the shell' to get the fender skirts taut while keeping the curved endcap c-channel meeting the floor & outriggers. Leaving that sheet of flooring oversize and trimming after you know* where the endcap lands might be wise.

truckasaurus · 01-20-2016, 11:47 AM

Removing the channel is the best approach in my opinion. If you left it in place the whole unit must conform to the floor. Rather than the loose shell which can be perfectly positioned on the channel I can't think of a good analogy but maybe consider a tent with a sewn in groundsheet being placed on a very uneven floor. The skin of the tent would look wrinkled. A separate ground sheet with a lip and a old school tent would conform to the ground and look straight as all the iregularities would be concealed

LifeIsRiveting · 01-21-2016, 07:52 AM

Ah yes of course. I hadn't thought about inserting the new sheets of sub floor into the double C-channel. That could be a problem if the channel is still attached to the shell.

Good to know that the double C-channel is only on the sides, thanks for that Wabbiteer.

I suppose it would be simple enough to position the side channels at the proper width (if it was measured previously and setting an accurate center line) but I am more concerned about skewing them fore/aft in relation to each other and not lining up with the shell. Or can you just leave them loose as you bring the shell down, adjusting as needed?

I know that it will make a lot more sense when I get my hands on it. Its just that I find the mental exercise beneficial in planning and really wrapping my head around all the steps and sequencing so thanks for putting up with my hypothetical noob questions.

youngpeck · 01-21-2016, 09:23 AM

Quote:

Originally Posted by Mr.Anderson

I suppose it would be simple enough to position the side channels at the proper width (if it was measured previously and setting an accurate center line) but I am more concerned about skewing them fore/aft in relation to each other and not lining up with the shell. Or can you just leave them loose as you bring the shell down, adjusting as needed?

I did just this on mine. Then, when the shell was back down, I adjusted the opposing sections of C channel (very little was needed, by the way) and then secured them to the floor and to the outriggers prior to riveting the sides of the shell back on. And since the end channels did not hug the floor, I left them off and then, just prior to securing them to the floor, was able to push them forward and aft as I "stretched" the shell, as Wabbiteer describes.

I was doing a complete shell-off. The new floor is 3/4" marine plywood, and so I had to rout the edges of the floor to accommodate the side channels. By the way, I put in new side C channels (bought from Intermountain Airstream in SLC, conveniently close to me), and it was nice to start with fresh ones. The new C channel extrusion is more robust than what I took off; it grabbed a little more of the floor, is slightly thicker aluminum, and also ran up a little higher on its outside vertical profile. This made the riveting and bolting down easier and stronger, since I was drilling all-new holes in the new channel from both the bottom and sides.

A word of caution if you increase the floor thickness. I should have routed the curved ends as well for those channels to fit down into. Not a big deal, but having a thicker floor raised everything by 1/4 inch. Some people rout the bottom of the plywood when they do increase its thickness, which mitigates some of the resulting misalignment. In my case I also installed new front and rear hold-down plates, since the rivet holes in the front would have been too low with my higher floor elevation.

Good luck! You're on the right track.

LifeIsRiveting · 01-21-2016, 10:07 AM

Youngpeck: Nice to see a fellow '76 Caravanner!

Your description was very helpful and I'm pretty sure I can envision exactly what you did, so thanks.

If my double c-channel looks ragged then I might just weld up new ones that are slightly thicker and more robust like the new factory ones. Sure would feel nice to match drill fresh holes!

So based on your comment about having to router the new 3/4" sub floor I assume that the original is 5/8" correct? Did you feel that new 5/8" would simply be too flexible or were there other reasons I am not considering? Do you still feel that the 3/4" was worth the extra hassle and (slight) weight increase?

Thanks!

youngpeck · 01-21-2016, 02:07 PM

Yes, I had the 5/8" original subfloor. It wasn't in bad shape--only a few sections, like the rear, needed replacing, and even that wasn't too bad. We just felt like we wanted a fresh start, and the 3/4" was an obvious choice. If we were going to replace it anyway then I wanted something more substantial, and, yes, less flexible. It is now rock-solid. It is more weight but we have also installed new 3500-lb. axles. I also beefed up the frame in a few places. I was able to get good marine ply at a wholesale price. We also spar-varnished the perimeter to a depth of a good 18 inches, as many on the forums do.

There is a tremendous amount of information on this forum that you will find--and already have found--useful. Lots of very intelligent, dedicated, and sharing people who have given much thought to just what you are doing.

I took a great number of pictures, any of which I'd be happy to share, when and if you need detailed images.

It's cold and snowy right now in Utah, and I've put my project on hold for a while. Hope to get back at it in about a month. But so far I feel that I've made good, informed decisions on what I've done, and why. We'll have to have a Caravanner meeting sometime.

splyb · 01-22-2016, 11:26 AM

I would LOVE to see those pics. And, if anyone is aware of any threads that have pics of c-channels, please advise. I'm a newbie and am about one day away from having our 68 Safari gutted down to the floor. My plan is to then remove the lower inner skins. Then, I expect to find a fairly simple c-channel arrangement - an interior-facing c-channel into which new sub-flooring will be inserted. I haven't given much thought to how that channel will be attached to the shell and have assumed that this whole process could be done shell on.
Now, I'm a bit scared. What has been described in this thread sounds far more complex that I am anticipating.
Anyway, some pics would be appreciated.
Jay and Lisa

youngpeck · 01-22-2016, 12:38 PM

I'll post some pictures later today or possibly tomorrow. There are plenty of C-channel threads on the forum. Easy to search in the Google portion. Here are two (of many) good ones:

http://www.airforums.com/forums/f36/...ign-81451.html

http://www.airforums.com/forums/f46/...nd-119388.html