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-   -   XJ Subframe Repair (http://www.jeepforum.com/forum/f37/xj-subframe-repair-1376248/)

dagr8tim 06-02-2012 08:49 AM

XJ Subframe Repair
 
I've got about a 5 - 6 inch long section of subframe rot. The rot extends about 2 to 3 inches up the sides of the subframe from the bottom. I figure I'll need to cut out about 8 inches of subframe about 4 inch tall. I've got some questions.

- I've got an old 97+ steel XJ hatch. Could I use that for patch material, or is that too thin? The XJ is being retired from DD and will be used for offroad, trailer towing, and generally as a work truck. It will probably take some abuse.

The area is on a flat section of the subframe, so basically I just need to come up with a "U" section to replace the rot. Could I weld this with a 110 Flux Core welder, or should I farm it out?

Other than practice on some scraps and to prep any bare steel before welding. Are there any other tricks or tips I should be aware of?

Ironworker709 06-02-2012 10:15 AM

Since you said it will be used offroad only..you could do it yourself...a couple things to consider though...

You said you have a 110v fluxcore only machine..fluxcore with sheetmetal is a PITA for even seasoned weldors to do,it burns through too easy,go to your local weld supply store and see if they carry a quality .030 fluxcore and do ALOT of practice with it before doing the actual repair..if you even have the slightest undercut in the sheetmetal sub frame..it will crack in that area sooner than later...what kind of machine do you have?

I would probably go with at least 1/8" plate for repair,making the repair stronger than existing

When making a patch,make sure it has no sharp square edges..round off all edges....square edges are a stress riser in repairs like that,your weld pulls stress 1 way and around that corner pulls another way,causing a weak link...rounding the corners even's the stress out a bit to where it's all an even pull in a circle,making it a lil better.

If you have any questions needing attended to and don't want to wait for responses..you can also call me anytime..you know where to find my number...:thumbsup:

dagr8tim 06-02-2012 10:36 AM

Thanks for the info. I have a cheap little HF flux core welder that I mainly use for hobby/art projects that don't need much strength.

I've been trying to farm this out, but the local vocational HS won't do it and the guy who was supposed to stop by and give me an estimate this morning no showed.

I had originally planned on 1/8th steel or C channel, but was wondering if what I had laying around would work.

I'm looking for strength over beauty, because even though it's a 3rd vehicle. I still use it for things like hooking up the trailer and hauling things. Last weekend it was half a ton of scrap steel + a 600 pound trailer.

Maybe I'll take another run through the phone book for fabrication places that are local on Monday.

dagr8tim 06-02-2012 10:53 AM

Here's some pics I took this morning after poking with a screw driver and knocking the loose stuff off with a hammer.

https://lh3.googleusercontent.com/-j...-43-03_563.jpg
The line scratched in the undercoating indicates where I intend to cut. I'm trying to stay atleast an inch away from the rust hole edge to ensure I have solid metal.

https://lh3.googleusercontent.com/-T...-43-24_893.jpg
The inboard side of the subframe is rusted through also, but not as bad. It looks like a natural horizontal line where the good metal starts.

https://lh5.googleusercontent.com/-g...-43-32_236.jpg
A peak inside of the hole.

I'm hoping this is a fairly quick/easy/cheap fix.

my-jeep-earl 06-02-2012 05:29 PM

You probably already thought of this, but you might want to be sure to pull the fuel tank off before starting the work, just a thought!

dagr8tim 06-02-2012 05:51 PM

I'm not that brave.

ljrubitm 06-02-2012 07:10 PM

After you fix the rust hole, look into some XJ Unibody Stiffeners.
http://www.jeepinoutfitters.com/scri...?idProduct=562
http://rocdogfab.com/index.php?optio...=1:latest-news

dagr8tim 06-02-2012 07:42 PM

Quote:

Originally Posted by ljrubitm (Post 13662454)

I have thought about those, but not sure how they work with rock rails. I've got a set of AJ's.

my-jeep-earl 06-02-2012 11:00 PM

Quote:

Originally Posted by dagr8tim (Post 13662168)
I'm not that brave.

To do the fix or pull the tank? LOL :confused:

dagr8tim 06-03-2012 05:31 AM

Quote:

Originally Posted by my-jeep-earl (Post 13663450)
To do the fix or pull the tank? LOL :confused:

It'll take longer to drop the skid plate and receiver than it will to drop the tank. Both of those have to come off no matter what.

I'm still shopping around for guys with more sheet metal experiences and better equipment to do the repair.


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