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Old 09-12-15, 16:56
David Dunlop David Dunlop is offline
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Join Date: Feb 2006
Location: Winnipeg, MB
Posts: 3,384
Default Bob

Factory original, from WilsonTruck Bodies, these wireless boxes were fitted throughout with 1/4 inch plywood. The ceiling is the first to be panelled and then the two end walls. Sides last. This way, the wall plywood adds support to the ceiling edges. As the vehicle moves, the roof will flex and there are dozens of screw holes up there just eating for water to leak in. Since the exterior roof is curved, water flows out to the sides where it could collect on the exposed ply edges, if the walls had gone in first. With the ceiling ply in place first, the water flows completely off the ceiling ply and down the backside of the walls. This prevents the ceiling edge from falling apart, or at least getting too warpy looking over time.

The plywood was made with animal glues back then and with time and exposure to dampness, the glues dissolve and the ply delaminates in situ. You end up with wavy crap as Robert described, very difficult to get a good measure from because some sections swell and others shrink.

Robert,

If you are going 1/2-inch on the plywood, you are going to encounter fitting problems with the ceiling light channels and copper bus bar at the very least. The Gen Box is also going to end up misaligned with the exhaust port in the floor.


David
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