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Severe frame rot..

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I am new to the Jeep world, and have several XJ's and going on my third 91 MJ this past week. The Jeep has "Severe" frame rot in fact it is not only rotted but it is basically gone from the front control arm to the front shackle for the leaf springs in the rear. Right side is basically gone, left side has some sections in the middle left, rear sections are good between the shackles and the front section suspension area is good. It basically looks like I will have to build a frame in the center of the Jeep out of box tubing and tie it into the shackle areas.


My question has anyone run into this severity of frame rot? The top of the box is jammed against the cab, floor pan is flexing with the frame, and yes doors are hard to shut. I notice one other person on this site had done some repair, but it wasn't near the damage that my frame has.


I wouldn't necessarily fix the Jeep but I am a glutten for punishment, and what else do i have to do but work on the other 12 or so Jeeps I have (models from 42 to 2005), lol. And I knew this Jeep from new, it has lol, only 54,000 miles on it and runs like a top, 4 wheel drive works excellent yet, every brake line leaks, new gas tank, new tires, inside of box is nice, shifts good (4.0 with auto). Thoughts (other than look for another Jeep and transfer the parts) on frame repair and if anyone else has tackled this problem before.


Thanks Joe from "RUST Belt of the NATION-Northern Michigan"!

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Welcome aboard! :cheers: While I really admire your desire to bring another MJ back from the dead, especially an HO, it's not worth the effort. Look for a nice southern MJ with a good body and blown engine or tranny, Renix or MJ, and transfer all your pristine running gear into it. You'll still save one and work a lot less hard. It sounds like that 91 is a terminal cancer victim mate.................

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Ooops typo, I meant to say 'not new' to the Jeep world, been building them since 12 years old, lol. Thanks for the comment on transfering parts, I have thought of that, but don't mind the frame work. I get some pic's when I get a chance so everyone can see them. I am just looking for someone who has rebuilt the center frame section.


Also add


2005 Jeep Grand Cherokee Hemi

2001 Jeep Cherokee XJ Limited, 242 transfer, Up Country 4 Wheel

1991 Jeep MJ, Long Wheel base 4.0, auto, 4 wheel

1991 Jeep MJ, short base, 4.0, auto 4 wheel

1991 Jeep MJ, snort base, 2.5, 4 spd, 2 wheel (sold)

1974 Jeep CJ5 304 V-8

1970 Jeep CJ5, 225 V-6

1966 Jeep CJ6, 225 v-6

1953 Willys Jeep Truck, 4 cyl, 4x

1945 Jeep CJ-2A, Harvest Tan

1945 Jeep CJ-2A, Pasture Green

1945 MB

1943 GPW

1943 GPW


Past Jeeps

1945 MB, 1967 Jeep Wagoneer, the 91 2 wheel drive MJ, 1987 Jeep Cherokee-2.5, 5spd 4x, 1964 Jeep CJ-5, 1960 Jeep FC170

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I think what you're thinking of is "hat channel", which is about 1/2" tall, 2" wide, and used under the bodies of CJ's typically as structural support for the body. More than likely I'll have to use 8" boxed tubing for the side rails. Like I mentioned before just curious if someone has tackled this problem before for uniframe's? Doesn't necessary have to be a Jeep, but there are so many of the muscle car era stuff out there that has been repaired as well. Thanks for the input!

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You got almost as many Jeeps as I have :eek: But I only "collect" MJ's and XJ's :yes:


I understand what your asking, and is it doable........Yea, lots of work, but it can be done. I got a '88 Olympic last year that had the same frame condition your asking about, the right side U-channel Uni-frame was completely gone, not even a section of it left, so, I hate to says, it turn into a organ donor for several other MJ's.


If you can find the Workshop manual M.R.278 (Bodywork) it shows the complete body construction of the Comanche, that manual shows up on e-bay often. That book will get you into how the frame/uni-body was built, all the spot welds, and how each component was connected.


I would think that a U-channel 3/16" X 4 or 5" would be useful for a frame re-construction. The original frame was built from 3 layers of 12 or 14 ga sheet metal.


Best of luck to ya trying to save a '91.

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Hey thanks for the tip I'll look for that book. I remember back in 94-95 I toured the Toledo Plant, and saw the running gear of a cherokee prior to the panels being put on, they were put together pretty quickly, and with all the laminated pieces i can see where they would rot very easily. What did this Jeep in was the fact it sat for about 6 years next to the guys house in tall grass, snowed around it in the winter, and the cycles up and down temperatures did it in. In Michigan I find that XJ's and MJ's that are used tend to hole up alot better than if they sit, just too much chemistry that kicks in that starts the rust. Then of course we are loaded with salted roads here, lots and lots of salt for all of the two-wheelers out there.

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Yep, any vehicle parked on the ground will rot right out, parked over stone, not a problem, but the Metal sucks up the moister from the ground, and just rots 10x's faster. I too have a couple of them that were parked that way, and it shows :shake:


If you get that manual, it will be a great help to you, I got one a couple years ago, and that's what made up my mind that the uni-frame replacement was not for me. There are only about 2,000 spot welds on the stupid thing :doh:


Oh........BTW.......Welcome to the CC :waving:

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