Rear Permanent Bed
Al Chernoff built a great bed in his coach. Irene and I had planned a very similar approach but had run out of time to build it last summer. This spring when I started to install the new bed, I found rot in the rear of the coach (the saga is now interesting to me).
The first step was to remove the rear ramp. It came up with difficulty. Screws around the edge came out fairly easily although some remained stuck in the flooring and just spun as I tried to remove them. The ramp itself wouldn't budge. So I drilled holes in the corner using a 2" hole saw and used them to get more leverage. The ramp came out (but there was rot underneath). That's why I spent so much time replacing part of the rear floor.
Once the floor was repaired, I builttwo side walls to box in a tunnel formed by the fresh water tank and the driver's side aluminum box. Materials were 1/2" plywood and 3/4 x 3/4 1/8 thick aluminum angle material. The aluminum was used as stiffeners and a place to screw the top of the bed base to the sides. The sides are held in place by a few off-the-shelf brackets. Screws were pan head #10 1/2" sheet metal with philips heads. Notice that I decided to route the fresh water hose across the top of the base, along with the heater duct to the bath module. I wanted these hoses to be available more easily in the future without completely disassembling the bed. Also, by routing the fresh water hose along the top, there are no "P" traps formed by the hose. The waterdrains into the tank better and can't pressurize the tank as easily.
Next I attached a cover tospan the center tunnel using #8 3/4 flat head sheet metal screws. (I discovered later that my plywood had inadequate stiffness. My initial check for level was fine, but I let the plywood sit overnight and it sagged without me noticing it. So, it pays top double check your materials at every step. I had to shim some later pieces to make them level. It's the first time that I've had 1/2" plywood deform overnight with no real weight on it.)
The original GMC configuration has a small triangular access panel cut into the rear portion of the water tank closeout panel. I found laying on the floor reaching in with one hand to be cumbersome at best. So I moved theaccess to over the top of the pump. The hole is about 16" square with a double layer of plywood around the hole to both stiffen the base and provide a shelf for the cover to rest on. I can reach all around the pump by lying on a piece of wood placed over the storage area.
Hoses and fittings are accessible. The fresh water tank hose clamp has minimal clearance between the bed base and the clamp.
The base of the bed storage area is level front to back and side to side. However, due to plywood warpage overnight, there is a 1/2" dip in the middle of the tunnel. Shims provide a solid base and closeout around the sides. The sides of the storage area are made from 1x12" number 2 pine with aluminum stiffeners attached to the top and bottom. The aluminum is 3/4 x 3/4 1/8 inch material. Screws are #10 5/8" pan head philips sheet metal screws. Aluminum stiffeners are recessed where needed an adequate amount to permit intersecting side pieces to also use stiffeners as mounting brackets.
The lift mechanism consists of two 90 pound twenty inch gas springs with an eight inch travel. Mounting to the wood is via one angle bracket and one straight bracket for each spring. The mattress board by itself is easily counter-balanced by one spring. Plan to put in two as the mattress adds enough weight that the second one is needed. For our bed, the two springs have enough lift that once the bed is raised a few inches, the remainder of the lift is completely assisted by the springs. The curb side lift is rotated so that the gas spring body is well inside the storage area. The driver's side lift is rotated the opposite direction. The springs were located 18" from the front edge of the mattress board for the board end. And the divider end was attached so that the bottom of the bracket was 2.5 inches form the top of the divider. Keep in mind that if you change the dimensions of the storage area the mountings may need to change.
A closeout on the curbside protects the wiring that runs along the top of the aluminum box. The sides of the storage area are spaced 74" from edge to edge so that it supports a double mattress. Cross members are placed so that they divide the storage area into three compartments form side to side. I placed mine so that the middle storage bay will hold two folding chairs plus our barbeque stand. (there's a lot of room left in that space.) Cross members are attached by aluminum brackets on each end. The storage space is 44" from front to back and 11" deep.
The board to support the mattress is 44" wide with a 9" fill board in the rear between the rear of the coach and the rear edge of the mattress board. The fill board is supported by two 1x12 number 2 pine boards that are stiffened by aluminum angle brackets to which the pine filler board is screwed with number 8 1 1/4 flat head sheet metal screws. Fresh water and heater hoses are run through the chase formed by the two boards. Anti-wracking for the chase is provided by the two side pieces of the storage area and the two dividers.
The mattress board is 3/4" shop birch plywood cut so that I could form a 4" lap joint. The joint falls over one of the storage divider boards to provide extra support. The rear fill board and mattress board are joined by a piano hinge 72" long. Each screw hole (there's over 70) has a #6 flat head brass screw (that's the size that my piano hinge requires).
I routed a 4" lap joint into each end of the mattress board pieces. (I needed to cut the board in two in order to fit it in from the front). The joint is NOT glued, but joined with 3//4" #8 wood screws staggered every4 inches. The resulting joint eliminates wracking across the mattress board.
The finished bed is about level with the bottom of the window. It's a little high off the ground for us shorter types, but the storage is great. We're planning to buy a small step stool tool box to hold our GMC tools and give us a boost into bed.
[PLEASE NOTE: although the manufacturer listed the lights for enclosed spaces, based on nearly setting my coach on fire, I DO NOT RECOMMEND using the halogens in enclosed spaces. I will be changing the lights in the next few weeks. In the meantime, the lights are disconnected.] The inside of the storage area has three halogen lights, each of which is aimed in a separate storage area. Lights are turned on as you lift the bed up using a modified door switch.. I will retain the switch but use florescents instead.