My otherwise clean 2001 XJ Sport has a rust area in the rear unibody rail area at the spot where the fuel lines go through a "tunnel" through the rail. Everything forward of the rear axle is very solid, as is the cargo floor, so I want to fix the rear rail area. I have a MIG machine and I'm experienced using it. The Jeep is a street-only daily driver. What do y'all recommend for fixing this? Lots of companies sell "frame stiffeners" that you weld over the frame rails, but I would think you'd want to cut the rusty spots out of the rails and weld in new metal first. Has anyone done this repair before, and if so, how did you do it. Thanks!

 

Generally you cut out all rusted metal and weld new metal in its place. Then use some type of coating it to protect from future corrosion.

Can you post some pictures?

 

Rear Uniframe rail rot area

 

I need to see a whole lot more before making a repair recommendation. What is seem is pretty bad, but the rust extends past the photo no doubt.
Is this salt damage? if salt, I suspect rust is bad throughout the truck, although no yet readily visible.

please post more photos.

 

The rest of the Jeep is solid. The rear 9" or so of the rear rails rusted where you can see the trailer hitch bolted to the bottom of the rails. The hitch brackets must have trapped moisture there. My plan is to pull the rear bumper, rear axle and leaf springs, and gas tank, fix the rails, and put it back together with new leaf springs, a rear disc brake conversion, new fuel pump and lines, etc. I'm just trying to figure out whether I'm going to have to fab all of the repair sections, or if there's a simpler way to do it.

 

I wonder what it looks like under the fuel tank ?

 

The cargo floor is totally solid as is the shock crossmember. It looks like the trailer hitch brackets blocked drain holes and trapped salt and moisture in the rails right above the hitch mounts. The pic is the only rot spot. It’s going to need the rear 9” or so of the rails fixed, and probably some spots in the rear crossmember that the bumper brackets bolt onto. Chrysler no longer makes the rear rail sections or I’d buy em new. I’m hoping someone who has done this has some advice on what works best.

 

I used frame stiffners on my 2000, after giving it a lot of thought it was the cheapest, quickest way to do it. They fit near perfect without any modification match all factory holes.

 

you will need to remove hitch, bumper, fuel tank, at minimum to assess what you need to do.

 

My adventure...https://www.cherokeeforum.com/f46/50...nd-sxs-262795/

It's worse than you think it is. Probably not this bad but worse than just that pic.

 

Man, my hat's off to you for tackling such a project! I would have cried a little, then drug it to a shooting range to use for practice! Nice set of skills you have there!

 

Fixable, my 96 Cherokee had the same issue in the same place, in fact mine was rotted all the way through. So bad that if you flexed out the suspension the body would twist so bad you couldn’t close the hatch. Bought frame stiffeners online and welded them on and did some fabrication to strengthen the frame back there. I was 16 at the time and it only took me a month to repair the whole thing, that includes waiting on parts to come in the


mail (new leaf springs, shackles, etc.

 

That's pretty nice before and after. I realize you were 16 at the time, but did you post a progression post or possibly a YouTube video for the frame repair project? Were you a trained welder, or a novice? What equipment did you use?

 

I did not make a video or anything like that. The only major welding job I had done prior was replacing one floor pan on that same Jeep, so I only had a few hours of welding experience. I just used a harbor freight titanium MIG welder, grinder, and a cutting wheel.