I like the hinges! I have a few ideas for you....
-extend the hinges across the tailgate. If you could tie into the 'bumper' and spare tire mounts that would make the entire assembly much stronger.
I've specifically designed the reinforcement so it mostly can't be seen, because I wanted to retain the stock look of the Jeep as much as possible, so you can't see much of the reinforcement part of the design in the photo I posted.
The tailgate reinforcement part of this design is separate from the hinges. If all I did was run the hinges all the way across the tailgate that wouldn't provide the torsional rigidity that's needed - the goal is to prevent the tailgate from twisting. The reinforcement I've designed and built completely eliminates twisting of the tailgate, and ties in to all of the key points in the tailgate, including the tire bumper and spare tire mount points.
Another reason the reinforcement part of the design is separate from the hinges is that I intend that the hinges could be used separately without the reinforcement, if all you needed was to replaced worn or seized factory hinges, or if you just wanted to upgrade from the factory hinges to a much stronger set of hinges. Judging from the number of stiff and seized cast-aluminum factory TJ hinges I've seen, I think there should be some demand for the hinges alone as replacement/upgrade parts.
-Do you have a bushing in your new hinges? A simple bushing with a trust pad on each end would make the hinge support a LOT more weight in the long run without getting loose.
Yes, the hinge pins ride in flanged bronze bushings. There is a zerk fitting inside the hinge for greasing the bushings, and in the event of wear, the bushings can be removed and replaced to rebuild the hinges to as-new specs. And the hinge pins themselves are 3/8" diameter stainless steel, which is much larger than the factory hinge pins.
-Find a way to add a support on the inside of the hinge to spread the load out to the body. The upper is pretty easy to tie into the roll bar rear mounting pad on a TJ ( and a little farther away on the LJ ). The lower is a little more difficult, but the load can be spread to the vertical portion of the wheel well tub on the 'outside' of the body.
I have designed inside-tub support brackets, but I haven't built them at this point. The TJ/LJ tubs have internal welded-in reinforcements for the hinges, and so far I've run over 7000 miles on- and off-road with a 73-pound spare plus the Safari Cab upper barn door attached to the tailgate (not to mention the weight of the tailgate reinforcement itself) and I'm very pleased with the structural integrity. But if internal brackets become necessary or desirable, they're an easy addition.
-Eventually the hinge at the door will become the weak link. It will basically crack around the mountings. Friend and I have ran similar, but less elegant, reinforcements on TJ tailgates. I think the long term solution would be to have a replacement tailgate that had internal support that tied the hinge area to the latch area.
I think I've accounted for those stresses in the design, but unfortunately you can't see that in the photo I posted.
Just a few thoughts, love your work.
I saw your jeep parked in Moab last week but no-one was around....
Thanks, and thanks for the thoughtful suggestions.