Please be aware that the dimensions of my rack should only be used as a reference.  My rig is a 1976 model, with the stock tire carrier on the drivers side, so the directions will reflect that.  I also built the cooler tray to fit a steel belted 54qt. Coleman cooler.  You may have to alter the dimensions of the cooler tray and/or the left and right racks to fit.  Also note that I built mine to accommodate a 35" spare.  The left half swings open first, then the right half.  I have aluminum diamond plate corners and the dress piece that fits under the doors.  If you are going to install diamond plate, I would suggest that you do that first.

Mounting the Latches and Hinges:

First find the centerline of the frame cross member.  Measure left to the existing catch.  Then measure right, mark and drill the holes for the right catch and mount it.  Metric nuts/bolts can be used here to match the other side.  I tack welded the nuts inside the frame cross member as this makes it easier to remove the catch, later.

The next step is to cut two 4" long pieces from the 3/4" x 3/4" angle.  One side needs to be cut/ground down to 3/8" so that you end up with two pieces of 3/8" x 3/4" x 4" angle.  The 3/8" dimension is subjective.  Use this as a guide when making yours.  It needs to clear the bottom of your vehicles doors.  Set these aside for now.

Again, measuring from the centerline for reference, locate where to drill and mount the right side hinges and proceed to attach them.  The use of a carpenters square helps here.  Once the holes are located and drilled, remove the hinges from both sides.  Slightly elongate (horizontally) the holes you just drilled.  This will allow for slight differences when the left and right carriers are built and ready to mount.  You will now remove the pins.  I had to break the welds on the inside of the hinge (stationary, bottom half) in order to get the pin out.  Try to salvage the nylon sleeves from the hinge top halves for later assembly.  Cut the heads off the 5/8" x 6" bolts and insert into the bottom half of the hinges (allow 3 1/2" of the bolt to stick out of the hinge) and weld the bottom.  I had the seam tack welded also.  You can mount the bottom hinge halves now.  Use fender washers on the inside of the tub. If you don't have diamond plate corners, you may want to make some backing plates to distribute the stress on the tub when the carrier is open.

Now, you will need to remove the tang from the upper hinge half (refer to Fig 3-2).  I used a cut-off saw to do this.  Dress the edges.  Set the upper hinges on the 5/8" studs using the salvaged nylon inserts.  Use the 1/8" flat washers from when you separated the hinge assy's also.  Make sure the flats are oriented inward.  If you take the upper hinge half and flip it over so that the cut off tang (flat) is next to the tub and then rotate it out 90 degrees, you will see that the flat lines up with the side of the rack.  Refer to r-rack1.jpg for a picture of how the upper hinge aligns with the side of the rack.

Here's where the dimensions may differ slightly from rig to rig.  It helps to have a friend assist you.  Measure carefully from flat to flat, making sure the flats of the upper hinge halves are parallel to each other.  Measure the distance of the top set and the bottom set.  The dimensions should be the same.  Figure the width you need for the spare tire and the width of the cooler.  Add 1/16" for gap and you now have the overall width of the rack.  This should equal the measurement between the hinges that you took earlier.  Adjust the drawing dimensions accordingly.

Left and Right Carrier Frames:

At this point you are ready to cut the 1" x 2" tubing.  Remember, measure twice, cut once!  Using a cut-off saw, miter the corners, chamfer the edges and weld them up.  I used a wire welder, as it produces cleaner welds.  Next, grind and dress all of the welds.  Procure a piece of material 1/16" in thickness.  Butt the left and right carrier halves together with the 1/16" material between (I used a piece of .063 aluminum cut to 1" x 15" as a spacer).  C-clamp the two sides together.  Sight down the length of the carrier and make sure both halves are straight.  If not, see what's causing them to be crooked (welds, slag, etc.) and correct if necessary.  Set this assembly on the two catches.  Align the cut edge of the upper hinge with the front surface of the carrier.  Adjust the second set of hinges (you did elongate those holes, didn't you?) to butt the hinges up to the carrier and clamp in place.  Set the latches on the catches and make sure the bail engages the catch properly on each side.  You may have to shim the catch out from the body to get proper alignment. Once everything is in alignment, tack weld the hinges to the carrier.  Once both sides are tacked top and bottom you can remove the C-clamps and spacer.  Carefully open the carrier halves.  They should swing freely.  Remove them and finish welding the hinges on.

Cut a 15" piece of 1/8" x 1" strap. This will be the backstop for the right carrier.  Leave 3/4" exposed and weld to the left vertical of the right carrier half.  See drawing (Fig-2) for placement.  I made 1/4" welds every inch or so.

Set the carrier halves on the hinges.  Don't forget to use the nylon inserts and flat washers.  Go ahead and snug down the Ny-lock nuts at this time.  Clamp the carrier halves together, making sure both halves are straight.  Set the backstops (3/8" x 3/4" x 4" angle) on the bottom catches, behind the carriers and snug up against them.  Refer to l-latch.jpg and r-latch.jpg.  Tack the backstops in place.  Open the carriers and remove the catches.  Weld the sides and back of the backstops to the catches.  Reattach the latches to the tub.  Close the carriers against the backstops.  

The next step is to mount the latches.  Refer to the pictures for placement.  The center catch needs to be cut (Fig-1) and welded (c-latch.jpg) into place.  I drilled clearance holes and recessed nuts into the tube and welded them in place.  Nut-serts could be used here if desired.  I believe that recessed and welded nuts will support more weight and withstand more vibration and shock than Nut-serts.  Again I used Metric nuts and bolts.  Nut-serts are available in Metric, also, should you want to try them.  Once you have the latches mounted and they are snug, we'll turn our attention to mounting the tire carrier and building the cooler tray.

Tire Carrier:

Cut two pieces of 1" square tubing and weld them into the left carrier (Fig1).  Placement will vary depending upon the size of your spare.  Fabricate two 7 1/2“' x 1" x 2" pieces (see Fig 5, item 6) and refering to (Fig1), weld in place.  I welded top and bottom caps on before welding them to the carrier. 
 
 

Using the spare tire bracket as a reference, mark the six mounting holes and flush weld nuts or install Nut-serts.  Again, I used Metrics.  This completes the tire carrier.

Cooler Tray:

To build the cooler tray (Fig6), follow the dimensions in the drawing, adjusting the measurements to fit your cooler. I don't think you will be physically able to go larger than 54qt. If you have a steel belted Coleman, use my dimensions. I did measure one of the new plastic Coleman 54qt. coolers and they are about 1/2" longer than the steel belted ones. By the way, Coleman doesn't make the steel belted coolers anymore. If you don't have one and want one, try the swap meets and garage sales. I found four in one day at the local swap meet. Two were in excellent shape and I paid $10.00 each for them. They are available. The advantage of the steel belted cooler is that you can attach right angle hood latches to the cooler via pop-rivets and secure the cooler to the 1/4" loops (see Fig 5, item 7) on the tray. This makes it easy to gain access to the cooler while out on the trail. I do use a bungee cord over the top to keep the lid secure, though.
 

I made 1" x 1" x 1/4" bosses (see Fig 4, item 5) to weld to the sides of the tray to allow sufficient thickness to tap a hole (5/16-18) into the side.  Make the 1" x 1" x 1/4" hinges (see Fig 4, item 3) and weld a pair to the top back of the tray.  The other pair of hinge halves (see Fig 4, item 3) that will weld to the carrier can be placed on the inside or the outside.  I used 5/16-18 x 1" bolts and Ny-lock nuts for the hinges.  I also inserted a 5/16" flat washer between the hinges. The cooler tray needs to be mounted as far right as possible (r-rack1.jpg), so as not to interfere with the carrier center latch.  In placing the tray, pay attention to how it aligns at the top of the carrier when folded up.  You need to mount two 1/8" x 1" x 1 1/2" tabs (see Fig 4, item 4) at the top of the carrier (r-rack1.jpg) to secure the tray in the upright position.  These tabs will align with the 1" square bosses (see Fig 4, item 5) on the side of the tray.  Lastly, fabricate the two braces (see Fig 5, item 8).  Again I emphasize, use my dimensions as a reference. Make your own measurements before cutting and/or drilling. These are used to support the tray in the open position. Lower the tray to a right angle from the carrier. Measure the distance from the center of the boss to the center of the tab (see Fig 4, item 4). This will be the distance you will use to drill the holes in the braces. Weld a 5/16-18 nut to one end of each brace, centered over one of the holes. These will attach between the bosses (see Fig 4, item 5) and the tabs (see Fig 4, item 4). See picture r-rack3.jpg. The last step in construction is to cut the oak slats, bevel the edges and mount. Five slats are equally spaced and 10-32 stainless machine screws with stainless flat washers are used to attach the slats.  Counterbore the slats to recess the screw heads and washers.  The screws are trimmed flush with the bottom of the tray.  The last thing to do is disassemble everything and powder coat or paint it.

Hopefully the drawings and pictures will help to show how everything goes together. If you have any questions please contact me and I'll try to provide answers. I can be reached at toyman@jps.net or if you are in the Sacramento area, give me a call and come on by, I'm in Orangevale and am listed in the phone book. I would like to thank 'Cardinal Fang', Bill Jackson TLCA# 6607 of Folsom, CA, who volunteered to render the CAD drawings of my sketches.
Joe Melhorn, TLCA# 1484
Orangevale, CA (near Sacramento)