Carnage assessment? Time for a new unibody or is this repairable?

[blistovmhz]

Finally bump-stopped the rear properly on Friday, and hit some new trails Saturday. Trails were much less technical than we normally do. All very mild, high speed stuff.

No idea what I did, but I managed to do some damage. Most of it is simple stuff, but the unibody I'm not sure is worth repairing at this point.

Somehow, despite the bump stop being set correctly (finally), I managed to tear out the upper rear passenger shock mount. I'm guessing it'd been fatigued from multiple hits before the bump-stopping.

Not a big deal. Throw a new bar together and call it a lesson in stress mechanics.
This hadn't broken free until last night on our way home from the lake (all highway) but I noticed it on the way out (saw the crack).

Next up, I managed to overheat the brakes. I'm not sure if it was just the pads fading, or if my fluid was boiling, but it sure was difficult to stop at the bottom of the hill. Front was smoking. Rear was hot, but not extraordinarily so.

Then last night on the way back from the lake (on the way there it was fine), my t-case started slapping. Had to pull the front DS to drive home. Front DS of course, had a stripped bolt on the t-case side and I only had an 8mm wrench (no socket) and socket is required to get the front bolts out. Instead, I just dis-assembled the front joint and had to break the ear off the double cardan joint (last bolt just wouldn't come out). Drove home smoother than it's ever driven. I've known for a while the DS was on it's way out so I wasn't too upset. I have a couple spare 231's anyway so this isn't that big a deal and I half expected it from the day I finished building it.

Here's the real problem though. My hatch doesn't wanna open/close. Noticed this last night as well. The hatch is shifted towards driver and doesn't wanna latch. A little coercion get's it closed. When I looked at it this morning though, I noticed that my bumper had run into the door, which is crazy because there's about a full inch between the two.

So the big question... Is it time to just build up a new shell? I can't imagine how this one tweaked out so far. It's got 3/16 stiffeners along the bottom and half way into the wells, two massively stiff bumpers, both of which go at least 30" into the rail, the front is all plated out, and the rear is mostly plated out with 3/16 and 1/4".
I guess it's worth noting that I didn't start plating until I knew it was necessary . Always a bad idea.

But, are we pooched here on the rear, and if not, is it worth fixing, knowing the uni's been tweaked that far out? Is it time to throw everything under a new shell? If so, is this time to just plate and cage it from the get go?

Also, my rig is 5000lbs right now. I have no idea how. I look at rigs like Cal's KOH "car" which is fully caged and plated and he weighs in 600lbs lighter than mine. How the ****?

Cal, how's your uni been holding up and how hard do you beat on it? I generally pick the hardest line I can find and I'm usually pretty smooth over most stuff, but I do smoke it pretty hard on the high speed.

Who's got pointers for plating/caging, as I'm clearly going about it the wrong way at 5000lbs and it's still twisting. (yes, I'm aware I could've used some triangulation, but again, very few guys have a full cage and very few manage to twist their uni's out this bad on a mild trail.

Should I just bend it back and start caging?

 

[831_xj]

I'm not seeing an issue...but maybe I'm missing something? I was expecting something substantial..
My hatch is tweaked/offset to the drivers side as well. I would just take it off see if you can adjust it some. Otherwise just cut part of the top lip until it clears the roof.

I weigh 5100 with all camping gear tools spares the gf and my dog. Not sure how lol

 

[blistovmhz]

Yea, like I said, I know I can fix it, but I'm just not sure if it's worth fixing, knowing that the uni's already been tweaked a bunch of times. It really comes down to the long term. Fixing this shell is probably easy, but I plan on caging and finishing my plating (only about 3' of plating left to do). I don't wanna spend another $1000 on plating/caging on a shell if it's not going to be as strong as just picking up a virgin shell and moving everything over.

Realistically, I could pick up a good shell today for under $500 and move all my stuff over. It'd take about a week to complete, and I'd end up with a complete Jeep worth of spare parts.

Meanwhile, my current rig needs a new windshield and HVAC REAL bad. I'll spend as much on fixing the current Jeep as I will to just move everything over. I'm also not sure if I'd rather swap an HVAC, or swap my entire drive-train, suspension, and interior over Can't decide which would be more work.

It really comes down to "is my current Uni worth saving, when ultimately the cost to swap will be roughly equivalent" ? Is the frame damage going to affect me in the future? Can I apply what I know now to build my next rig a bit lighter/stiffer? Keep in mind, this is my DD.

Also, on carnage, come on! I tore a shock mount, wrecked my t-case, broke a drive-shaft, tweaked the shell, and melted the brakes, all on a relatively mild trail system . That's not a bad days work.

 

[GordoSmasho]

Seams a hell of a lot straighter than my 2door. Ive landed on my frowny rockerguards so much that my b pillar is tweaking my roof line and rear window surrounds have wrinkles. Doors barely close. I have some pretty good wrinkles and almost tears in the trans tunnel as well. Just massage it and call it good.

 

[cal]

Looks pretty strait to me. Is the wheelbase still true? If so I'd run it.

 

[blistovmhz]

Looks pretty strait to me. Is the wheelbase still true? If so I'd run it.

I've no idea on wheelbase. Can't get a clear measurement anywhere, which I suspect is because the frame is tweaked. As I've bitched about MANY times on here, I can't get it to track straight, but I think that's probably due to my draglink/trackbar angles (which are relatively flat and parallel, but I think the trackbar being 4" shorter is killing me, but there's nothing I can do about it until I throw in some coilovers to make room).
Pulls drivers on acceleration and passenger on deceleration, but braking deceleration is straight, which is why I'm still confused. I figure if front end is the cause, hard braking should pull me to passenger way harder than engine braking, but it's dead straight and true on braking.

I suspect it's gotta be something in the rear end causing the torque steer, but I can't figure out what. When I measure front>rear diagonally, it's bang on, but SOMETHING is messing it up. Also, it'll very occasionally pull passenger on accel (like, 1 out of every 200 starts).

Everything is tight, all my joints are good, front alignment is good (verified all possible parameters), self centres nicely. Just whenever there is positive torque, it wants to go left, and negative torque it goes right. Makes it a bit tiring on the highway.

Durango box, chevy pump, 4.5" drop pitman, WJ knuckles, 1 tonne crossover OTA. I originally thought the issue was being caused by the passenger leaf wrapping on torque, which pushes the passenger body down, and with the high angle of my leafs on the shackle relocations, that would push the passenger side of the rear axle backward while drawing the drivers forward, which would make perfect sense. But now with the 63" chevy leafs, the problem remains identical despite the leafs being dead level and wrap is substantially decreased.

I just can't think of a mechanism by which a twisted frame would cause this.


*edit* I measured the hatch side of the unibody. It's square. Looks like somehow, the passenger side of the hatch hit the bumper mount (or the mount rose up to hit the hatch) and bent the drivers side hatch hinge forward. This makes perfect sense except that I can't figure out how the bumper hit the hatch. The bumper has to move a full inch to hit the hatch. All I can think is the XJ uni flexes enough that the hatch ran into the bumper mount (cause the bumper mount ain't going to flex), and then the uni flexed right back where it belongs. I didn't think they could flex that far and spring back, but that's the only thing that makes sense.

TIME FOR A CAGE!

That said, I've gotta figure out how to cage this beast without increasing my COG. Thinking I'll have to figure out a way to lose the tire carrier, as well as lose an inch or two of lift. Was going to throw coilovers in the front anyway as I recently discovered my front shocks aren't quite large enough volume to deal with high speed trails, which gives me an excuse to throw on some coilovers and drop things down a little.

 

[Weasel]

Back it into a tree and see what moves or hits. Why start over of all you going to do is replate the entire frame again?

As for wheel base, measure front to back of the tires on the same spot each side.

 

[blondejoncherokee]

I don't see anything wrong id run it

 

[Hoooper]

Get any pics of the unibody issues?

 

[blistovmhz]

My last post. Discovered the hatch hinge was the problem, NOT the uni.

I still don't know that my Uni is otherwise straight, but the hatch issue definitely isn't a Uni issue. Case closed. I feel like an idiot