I had also heard that if the shock bar is tied into just the floor that eventually it starts to fatigue the floor and the whole back of the jeep. That the floor wants to be pushed up and the frame wants to go with it. Does this take quite a bit of abuse?
Mine was tied into the top of the frame, with plates welded to the floor, the top of the frame rails (we cut the floor out and dropped the plates almost flush with the floor) and welded to the sides of the rails from underneath. From the looks of my XJ now, the entire bar was yanking upwards on the floor and frame, and tweaked the hell out of the body. first the floor started to buckle around the stock shock crossmember underneath, then all the spotwelds pulled out around the rear hatch opening, then this happened:
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The floor started to tear around the foot plates.
Next this happened:
(click for bigger pic)
That is the drivers side rear wheel well, just below the door handle for the rear door. That crack started as a tiny pinch and crack in the paint, and within an hour or so it looked like that. by the time the weekend was over i could fit a cigarette butt in there. That crack runs from the frame rail inside the wheel well, out and around, into the interior, and inside to the bolt that holds the rear seat back in at the bottom. the drivers side is the worst but the passenger side is about 70% as bad.
It is also separating here, between the rear window and the rear door on both sides under the rain gutter:
I am NOT easy on my jeep, at all. I beat it hard, without a cage and without frame stiffeners, so this was bound to happen anyway. But I think the shock hoop definitely helped it along quite a bit. the entire rear half of the XJ is loose, you can grab the rear bumper and move it up and down and watch the cracks separate. If you go easy on your XJ in the whoops and dont point it in one direction and floor it for a few miles like i do you should be fine. I won't be putting a hoop in my new XJ without a full cage though.
Hope this helps some, the unibody is just too weak to hold up to the abuse by itself. when you stiffen one part up the stress just moves on to the next weakest link.
Oh my transmission tunnel has about a 9" crack in it just ahead of the rear seat support too, don't have a pic of that one. it's big enough to put a finger through :gee: