Generally I've seen them from the upper hinge to the lower corner. I think those are backwards. Look at the orientation of the turnbuckles above.

Maybe try the opposite diagonal on the back?

No, those are not backwards.

Wheels are not needed either.

THis needs to be addressed.

http://forums.pelicanparts.com/uploa...1677182105.jpg

Then the twist.

This

http://forums.pelicanparts.com/uploa...1677259554.jpg

has the diagonal in compression. (perfect for wood.)

A tension cable going the other way can be added (strategically) to counter the warping.

http://forums.pelicanparts.com/uploa...1677262501.jpg
I'd first open the gates and added some big lag screws at the locations marked in white.
Countersink/screw the heads in so they won't interfere with the closing gap.

Back to this (edit ^ yep ^ but more screws up top.)

http://forums.pelicanparts.com/uploa...1677182105.jpg

Screw and glue (epoxy or urethane)

Use a bunch of 3" $10 SS decking screws going in perpendicular to the hinge mount screws (don't let them interfere.)

Then move the hinge back up top. But get bigger hinges. Some that allow the hinge screws to be further back on the post.

Then I'd jack up the panels so they're squared up and put some deck screws into the existing diagonals.
If the existing hinges are still presenting a problem at the post attachments I'd remove the screws and thru bolt them into place adding a backer/doubler on the far side to really squeeze the post.

Maybe

http://forums.pelicanparts.com/uploa...1677260608.JPG

You can see how these will move the post mounting holes farther back.

I will also point out that 'over closing' the gate can rip hinges off like that.

The gate is a really long lever arm that carries some inertia with it on closing.

If the only 'stop' is at post, some big forces can be applied to those hinge mounts / the post.

Adding a small stop at the center, where the gates converge, would be smart.

Yup, the edge distance of the post mounting holes is what would be considered the weak link here. Not enough 'meat' in the post to support that weight.

http://forums.pelicanparts.com/uploa...1677264103.JPG
This type of hinge allows you to put the hinge pin almost in the middle of a 4x4 post.

Great ideas, fellas! Thanks a bunch.

Wish you were closer I'd offer to help. Buildin' stuff like this is great fun since I don't have to do it for a living.

Thanks Scott. I suck at building stuff but I’m willing to learn and since I’m retired, I have the time.

Plywood gussets on an outdoor gate? Are you guys using PT plywood? Even if it held up to sun and water I can't see how esthetically pleasing that gate would be

She's a real looker now. lol

Misc:
-Five or six latches per side.
-Metal turnbuckle rods on the surface to help keep square.
-Center stop per above.
-Add a row of self-latches between the gates. All attached with a single lift rod to tie top/bottom together.
-Add a drop-bar into pipe-hole both sides. They will also have those standard rotating forks to interlock.

-Full length heavy duty piano hinges. Super strong and ex$ensive. But if something goes wrong they will rip out the side posts before breaking.
-Inset metal arc wheel tracks (must be absolutely perpendicular to the post or it will tear it off). These are generally not a good idea because one little stone will stop it cold and the gate will flex over at the top with momentum.

-Single-piece lightweight gate .
-Folding closet-door linear style gate.

Wheels are another thing I don't like on swinging gates. Not only do they not work well but wheels are a remedy for crappy gate design.

The wheel thing won't work for my application, I don't think. My driveway slopes so when I open the gate, the wheel will hang unless it's on a spring mechanism and extend down to keep contact with the concrete.

Looking at this picture I can see that the driveway slope is acting as the gate stop. (poorly)

http://forums.pelicanparts.com/uploa...1677182084.jpg

I would be inclined (happy pun) to install an adjustable foot/stop on the inside of the gate, that would be the first thing to hit on closing. Adjust so each side stops at the same place and does not over close the hinges. ...or warp the gate.

Dragging that gate on the floor from it sagging is what make it twist like it. It just sagged over time and I bet it worked well when new. Shim to square it up, stiffen with plywood and you can get a lot more miles out of it. A little paint, it will all go unnoticed but you gotta to relocate that top hinge and get rid of that 2x. Squaring that gate is a breakfast burrito job and be done by noon and no beer needed maybe but just a couple of swear words to keep your man card. Good luck and let us know how it goes.