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leylandauto 09-16-2012 02:41 PM

99 TJ Subframe/Torque Box replcement
My Son in Law's 99 TJ has some rust issues that need cleaning up before Inspection. The floors will need replacing but they can be fixed temporally for this year. The part tnat NEEDS full replacement is the torque box on the passenger side. The section with the middle has pulled right away from the floor etc. I have one of the replacements from Classic as I found here (very nice quality part btw). Any tips/cautions/caveats etc on the process? Should I expect to have to cut off the mount hardware? Ok, to get used mounts for now? I see them on ebay from time to time. Warnings/tips about getting everything dead on for mounting locations? Are there things I have to do like bracing when I have all three mounts off on the passenger side? I have a good selection of air tools, two angle grinders (I like to load one with a cut off wheel and one with a grinding wheel, saves time). I have a Lincoln 135 welder with CO/2-Argon. Should I change gas to straight Argon for better upside welding (saw that on some forum thread). I think I have a couple of pics here and will try to post them.
Thanks very much for any help.
Carl French
Alfred, Maine

leylandauto 09-16-2012 02:45 PM

A not so good phone picture of part of the subframe;

leylandauto 09-16-2012 02:46 PM

The rest of the 6 picture album (nothing great, but random pics under the car in their driveway.

leylandauto 09-16-2012 02:48 PM

Easier to replace entire section or cut and patch mount areas as needed? Anyone know what size spot weld cutters work well with Jeep spot welds? My experience is pretty limited to rusty old British cars.

matt88-8 05-10-2013 06:32 PM

Well im looking into the same thing, lets hope for some advice..

ChrisJeepTJ 05-11-2013 05:44 PM

Check out this company from Wisconsin, Classic Enterprises at They make full OE replacements for the torque box (the metal box that mates the body mounts to the tub). I ordered both sides for my 99 TJ and was 100% impressed with the quality and attention to detail. Their metal work is heavy duty and each torque box is hand signed by the fabricator with their name and 'Made in the USA' which shows they are taking pride in their product. Order these and it will solve your problem for the rest of your jeep's life.

Once you get them, it's just a matter of removing your mounts, grinding out the old box and welding in the new one. Be sure to hit the bolts on the mounts with some PB or similar because if they're like mine they will be fused on there.

Don't wait too long on this either. Now that the metal is rusted and compromised, salt etc from the roads will be blasting in there and you don't want that rust migrating from the torque box into the tub which will just compound the problem.

One final suggestion: before ordering, check the other side of your jeep too. My drivers side was like yours and thought my passenger side looked ok at a glance. On closer inspection, it was starting to flake just a tiny bit and with a little picking, I discovered it was basically held together by some paint and needed replacing too. I saved some money on shipping by ordering both sides at the same time.

00silverTJ 05-12-2013 07:11 AM

This is in my future. I wish I could put all of that money and time into something else.

deathmedic 12-09-2014 10:26 PM

ok guys how hard of a job is this to replace? Is it basically unbolt the mounts remove the bolts and lift the body up to cut it out and set the body back down and allow the Mounts to locate the new Torque Box and weld in place?

Nlburden 12-10-2014 07:31 AM

There are a few ways to go about it. My sub floor was gone as well ( reason why i bought my jeep for less then 800$ ).. I cut out all the rust with a grinder with a cutting disc. Once I had the subframe cleaned up nicely, I used 3 inch channel and 1/8 inch plate and welded everything up. I welded the channel directly above the body mounts and welded nuts into the channel to bolt the body mounts on. I then welded metal to the body and made the whole area look like a giant skid plate. It is strong, It is protective. Sucks to cut and weld but it works.

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