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  #1  
Old February 4th, 2018, 14:33
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sinat01 sinat01 is offline
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Angry Unibody repair

So while removing my factory hitch the other day, I ripped the rearmost bolt on the pass side down through the unibody. it is rusty but the steel seems ok on the bottom and good on the sides of the rail. My thoughts to repair and strengthen the unibody back there was to cut the bottom of the rail, drill holes through the side and put 1/8th" steel on the inside of the rail then used the drilled holes to plug weld it it. then close up the bottom of it by welding in 1/4 or 3/16s plate. then do some rear stiffiners to tie it all together.
Thoughts?
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  #2  
Old February 4th, 2018, 17:46
Jim Malcolm Jim Malcolm is offline
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Re: Unibody repair

I wouldn't cut a hole in the side as you propose, at least not before trying to fish it in through the hole in the rear panel, behind the bumper.

Consider these: http://www.nates4x4.com/Retro_fit_In...tie-in_xjr.htm

Whatever you do, you absolutely must make sure that you deal with the corrosion issue, both what's there already and what you're going to have down the road due to welding to it, or you'll be dealing with it again in short order. Check out weld-thru primer and paint products with plastic tubes and special nozzles (Eastwood comes to mind) to paint inside the rail once you're done.
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  #3  
Old February 4th, 2018, 18:06
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Re: Unibody repair

I did look at the eastwood kit a few times to coat the inside of the unibody. and I want to make a set of those tie ins myself, but I have to fix the bottom of the unibody first. If I can figure out how to post pictures other ways besides photobucket I would be in business, and could show you what I did. I was just looking at rear frame stiffiners that wrap around that part of the unibody where the hitch usually bolts to, which would also fix the problem (I think)
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  #4  
Old February 4th, 2018, 18:11
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Re: Unibody repair

With those tie ins, would it be possible to bolt them in, get some 3/16s steel, drill the bolt holes through it, form it into a tall C, bolt to the tie ins and then burn the 3/16s into the unibody? if that makes sense lol
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  #5  
Old February 9th, 2018, 12:01
Jim Malcolm Jim Malcolm is offline
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Re: Unibody repair

Sorry I missed the plurality on holes. I would not weld in through the side of the frame channel. The likelihood of causing issues outweighs the benefit to the fix. Fit the widest backing strip in there you can, round the edges, ideally with flanges, and you're golden. I don't know that I'd worry much about fixing the oem sheetmetal unless it's really an issue. Check the bolt torque from time to time and let the two pieces deform in on each other. It helps in the horizontal direction...

We were towing way more than we should have in my buddies ZJ when the studs in the bumper mounts (they're much different than a XJ) ripped through the frame channel. Had to fix it within 24 hrs. We used 1/8" x ~1.25" flat bar and 1/2" gr 5 hardware. Basically the same as aftermarket XJ backer strips. Finished the tow and has been like that ever since. You can do way better than we did...

You noticed I mentioned 1/2" gr 5 right? Any sort of weld in reinforcement is not required for this fix.
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  #6  
Old February 12th, 2018, 12:34
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Re: Unibody repair

I ordered some nates4x4 rear bumper tie ins, which should help the issue. im also gonna put some 1/8" over the bottom of the unibody to tie it all together
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  #7  
Old February 12th, 2018, 16:33
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Re: Unibody repair

So I found some more rust (surprise LOL) but there is a bad spot on the drivers side part of the hatch frame. it is where the seal sits. it has rusted clear through in about an inch or two section. whats a good way to repair this?
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  #8  
Old February 15th, 2018, 14:17
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Re: Unibody repair

so I come up with a game plan to repair it. I ordered the nates4x4 frame tie ins (which are beefy, and on sale) and when the weather cooperates I am gonna get a set of IRO rear frame stiffiners. I figure both of these combined will make it as strong as possible without serious modifications.
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  #9  
Old February 15th, 2018, 14:23
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Re: Unibody repair

sounds like a plan
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  #10  
Old February 15th, 2018, 14:24
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Re: Unibody repair

Quote:
Originally Posted by Jim Malcolm View Post
I would not weld in through the side of the frame channel. The likelihood of causing issues outweighs the benefit to the fix.
How do you recommend welding on frame stiffeners, which done right should go from bumper to bumper??
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  #11  
Old February 15th, 2018, 14:24
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Re: Unibody repair

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Originally Posted by denverd1 View Post
How do you recommend welding on frame stiffeners, which done right should go from bumper to bumper on the outside of the frame rail??
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  #12  
Old February 15th, 2018, 14:25
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Re: Unibody repair

WTF why can't we edit?
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  #13  
Old February 16th, 2018, 10:56
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Re: Unibody repair

Quote:
Originally Posted by Jim Malcolm View Post
Sorry I missed the plurality on holes. I would not weld in through the side of the frame channel. The likelihood of causing issues outweighs the benefit to the fix. Fit the widest backing strip in there you can, round the edges, ideally with flanges, and you're golden. I don't know that I'd worry much about fixing the oem sheetmetal unless it's really an issue. Check the bolt torque from time to time and let the two pieces deform in on each other. It helps in the horizontal direction...

We were towing way more than we should have in my buddies ZJ when the studs in the bumper mounts (they're much different than a XJ) ripped through the frame channel. Had to fix it within 24 hrs. We used 1/8" x ~1.25" flat bar and 1/2" gr 5 hardware. Basically the same as aftermarket XJ backer strips. Finished the tow and has been like that ever since. You can do way better than we did...

You noticed I mentioned 1/2" gr 5 right? Any sort of weld in reinforcement is not required for this fix.
so how would you recommend welding on stiffeners?
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  #14  
Old February 16th, 2018, 14:28
Jim Malcolm Jim Malcolm is offline
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Re: Unibody repair

Can't help much with the door seal lip repair, other than to say that doubling up the metal, either on the body or the lip, doesn't seem like it would cause an issue as long as your additional metal isn't too thick. I'd take a good look at it before doing it, but I don't think you need to butt weld your fix in. Ideally you could get to the backside.

Regarding the stiffeners, there are quite a few how-tos out there that will give you a much better idea than I can in text. I cleaned off ALL of the rubber undercoating with a wire wheel. Marked both the body and the stiffeners where I as going to weld (skip along perimeter) and removed all paint from body at those locations. The rest I just scuffed up a bit. Weld-thru zinc primer the whole area. Full paint prep on backside of stiffeners and weld-thru zinc primer. Seam sealed the perimeter except for a few gaps along the bottom, then paint and undercoating.

Angle the weld wire more towards the stiffener than the body (so not the usual 45), start welding into the stiffener and then draw it over onto the body, spending more time on the stiffener than on the body. You'll get the hang of it soon enough.

Then clean-out the inside of the frame channels as best you can and paint the backside of where you've welded. i used Eastwood products with the tubes.

Rear wrap-around stiffeners are a bit of a PITA to install because you need to push at an angle to form them into place, with the top corner being the worse since you need an "extension" on your jack. Just be prepared for wanting to push forward on your XJ when putting it up on stands. Make sure you have it where you want it before pulling the trigger...

I'll forewarn you, if you're like me, it starts out as just a stiffener install and then you look a little bit to the inside and see that oil covered mess and the "while I'm here" syndrome kicks in and before you know it the motor is out. To do full front to rear stiffeners, you're going to want to have both axles out, or darn close to it. Before you know it, you end up with 2 XJs because you couldn't get the 1st one back together before winter...

Depending on a whole lot of factors, I personally would not add stiffeners just for this repair. The risks of the stiffeners causing more issues with rusting out of the frame channel is higher than the benefit with regards to fixing the rusted out hole. I personally would get a set of shackle relocators that bolt to the underside of the frame channel (HD Offroad Engineering comes to mind) before I'd add stiffeners if the sole purpose was to fix the issue at hand. That being said, I have stiffeners on both of mine.
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  #15  
Old February 17th, 2018, 08:00
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Re: Unibody repair

Quote:
Originally Posted by Jim Malcolm View Post
Can't help much with the door seal lip repair, other than to say that doubling up the metal, either on the body or the lip, doesn't seem like it would cause an issue as long as your additional metal isn't too thick. I'd take a good look at it before doing it, but I don't think you need to butt weld your fix in. Ideally you could get to the backside.

Regarding the stiffeners, there are quite a few how-tos out there that will give you a much better idea than I can in text. I cleaned off ALL of the rubber undercoating with a wire wheel. Marked both the body and the stiffeners where I as going to weld (skip along perimeter) and removed all paint from body at those locations. The rest I just scuffed up a bit. Weld-thru zinc primer the whole area. Full paint prep on backside of stiffeners and weld-thru zinc primer. Seam sealed the perimeter except for a few gaps along the bottom, then paint and undercoating.

Angle the weld wire more towards the stiffener than the body (so not the usual 45), start welding into the stiffener and then draw it over onto the body, spending more time on the stiffener than on the body. You'll get the hang of it soon enough.

Then clean-out the inside of the frame channels as best you can and paint the backside of where you've welded. i used Eastwood products with the tubes.

Rear wrap-around stiffeners are a bit of a PITA to install because you need to push at an angle to form them into place, with the top corner being the worse since you need an "extension" on your jack. Just be prepared for wanting to push forward on your XJ when putting it up on stands. Make sure you have it where you want it before pulling the trigger...

I'll forewarn you, if you're like me, it starts out as just a stiffener install and then you look a little bit to the inside and see that oil covered mess and the "while I'm here" syndrome kicks in and before you know it the motor is out. To do full front to rear stiffeners, you're going to want to have both axles out, or darn close to it. Before you know it, you end up with 2 XJs because you couldn't get the 1st one back together before winter...

Depending on a whole lot of factors, I personally would not add stiffeners just for this repair. The risks of the stiffeners causing more issues with rusting out of the frame channel is higher than the benefit with regards to fixing the rusted out hole. I personally would get a set of shackle relocators that bolt to the underside of the frame channel (HD Offroad Engineering comes to mind) before I'd add stiffeners if the sole purpose was to fix the issue at hand. That being said, I have stiffeners on both of mine.
I must have misunderstood what you were saying above about welding to frame rail. Got it now

Sent from my SAMSUNG-SM-G930A using Tapatalk
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