Hi Jim, now you got me thinking!
Your correct about the size, or thickness of the barrel on the hinge, determines how thick of wood paneling can be used. I never considered using a thicker barreled hinge on my first panels, because I was stuck on the idea of staying with the hinges I had. Too bad, because I spent a lot of time on that first set, and $$$ because of fiberglassing both sides. I still think fiberglassing is worth consideration, because those panels were extremely rigid for the vertical load, were much more moisture resistant, and would not have needed, or benefited from aluminum backing struts like those still used by ATC campers, and which I added to mine for stiffness. So I ended up throwing them away, sadly.
I used birch bead-board paneling from Menard's, as it was the thickest paneling I could find that would still work with my hinges. I used the back, unfinished side of the panels, sanding them down, and applying a lacquer finish, because I didn't want to have horizontal lines on the lift panels, contrasted by the vertical lines on the wall paneling.
So, like I said, now I'm spinning the old thinker.
Here's a couple thoughts for you to consider.
If you went with up to 1/4" thick paneling, using those thicker hinges you found, that sounds doable. I would just make sure they would fold completely in half, flush, representing that center hinge's role, with some scrap pieces before cutting and finishing the panels. The hinge at the top of the panel, that attaches to your roof, also needs to pretty much fold completely, just like the center hinge because it folds up flat to the roof, folding completely over itself. So you might need the larger barreled hinge there too. The bottom hinge only has to fold 45 degrees, so I think they'd still be okay with thicker panels.
Another thing I would do differently, would be to ignore the pre drilled holes on the hinges a little bit, and move them over a 1/4", so that when you fold the panels, the rivets are not touching each other, because that is another place you'll cause binding, which in turns cause the wood to have to flex in order to fold completely. It also, in turn, places extra stress on each of the hinges. You also might need to flatten the rivets a little to get full folding.
Lastly, if you weren't already thinking about it, it's best to use "large flange" 1/8" rivets for the center hinge, and the the top and bottom hinges where the hinges attach to the wood panels. It was recommended to me to use 3/16" rivets to attach the top of the panels hinge to the roof, and of course hex sheet metal screws to attach to the camper wall. (You can find "large flange" rivets on e-bay if you look around a bit.)
If you are careful when you're removing the hinges from the roof, the holes will be preserved with no oversizing caused by drill bit drift. Get yourself a small diameter punch, the same size as the pin in the rivet, and hammer the pin part of the rivet through the head of the rivet, then drill the flange part until it pops off on the drill bit. When all are done this way, the hinge will pop off, and then you can push the remaining part of the rivet into the hole with a bit larger punch. It beats everything I tried, including grinding the flanges down flush with the hinge. Hope that makes sense.
When I referenced placement of the center hinge, I was meaning that it doesn't fold perfect center. When you remove your old panels, fold them in half and take note of the over hang you'll see on one of them, I think the bottom. This is the critical part that ensures they fold up properly when dropping the roof. I would put them exactly like your existing panels, right on the money. And keep each panel specific when putting them back, front re-make with old front panel, so your alignment stays true when the panels are attached. Take extra time to mark everything that makes sense to put it all back in the same place you found it. When replacing hinges, this will be very important, because you may not have the same holes to work with.
I hope I haven't come off sounding like a know it all, this was just a place I had a lot of struggles, and I'm just trying to be helpful.
Here's a few pics for reference.
On the last pic, there are two plywood boards cut identically in length, used to give you proper positioning of the hinge to the top of the camper wall. Make these before removing anything, if you're doing this with the side liner off, which you might not be doing. They could also be position in the corners, adjacent to the lift panels, if the side liner is staying on. Some people have just made a 2x4 support in that case. The idea is to keep your hinges at the right height on camper wall, and hold the weight while you attach them. Recommended by Marty at ATC.
Ok, that's probably enough out of me!
http://www.wanderthewest.com/forum/topic/12116-new-build-1981-grandby-to-become-a-hawk/page-11
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