Unibody Rust

I noticed when I pulled the carpet out of the cargo area I have a few rust spots. One of them is about 6-8 in across and when I hit the dirt and crawl underneath I can see where it is starting to flake off. It's not bad at all on the underside, but it is starting to flake. I know this is due to a leak in the roof from when the previous owner decided to put a rack on and not seal it well.

So what are my options? I saw an article a while back, that involved a YJ, they simply cut the rust out, put in a new piece of sheet metal (slightly thicker than the rest of the tub) and welded it up. Is it possible to do this on a unibody or is it too risky to mess with such a large section of it? Other ideas?

DO a search on this, it's been covered a billion times...

www.cardomain.com/id/poorboy_616 Click on the jeep and my article on rust removal is on page 4.

poorboy_616 said:

DO a search on this, it's been covered a billion times...

www.cardomain.com/id/poorboy_616 Click on the jeep and my article on rust removal is on page 4.

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I searched for it but didn't really find anything. I probably just didn't look hard enough.

Thanks

Level of repair depends on level of rust damage. Is it surface rust or has it eaten several holes through the floor? If it's just surface rust you can use a wire wheel or flap disk to clean it up then spray with rust converter or a good self etching primer. If it's eaten through large holes in multiple spots then it will need to be cut out and patched.

dave92cherokee said:

Level of repair depends on level of rust damage. Is it surface rust or has it eaten several holes through the floor? If it's just surface rust you can use a wire wheel or flap disk to clean it up then spray with rust converter or a good self etching primer. If it's eaten through large holes in multiple spots then it will need to be cut out and patched.

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If I lived in a wet climate, it would have already eaten through. Luckily I live in AZ, so there are no holes in the floor, but it is starting to flake underneath and I can see ares where it is starting to turn red-ish.

Judging by what you're saying, it is safe to cut out the rust spots and patch them with thin steel plating or the like? If so, then that is probably what I'm going to do, just for good measure.

Here is my 1984 XJ from this past weekend. Was wondering why my seat was turning into a rocking chair. Even my wife got into the ordeal by running the shop vac as I was picking it apart with a screwdriver before attacking it with my grinder and cut off wheels.

Since then, all rust has been cut out, frame re-welded with new thick stock and metal all prepped for new sheets. Not fun at all...

I cut up an old wash machine to fix the small rust holes in mine. then left the carpet out and painted the floor with herculiner.

Here are a couple of photo's of my 98. I'm waiting for FED EX ground to deliver a POR-15 floor pan kit. I'll post after pics.

That's actually not too bad. Looks like you won't have to replace any of the sheetmetal. Just make sure to grind the crap out of it. Orrrr you could mask off everything (dash, windshield etc) and sandblast it. Wouldn't take off as much material.

I'll just grind and wire brush it. Still waiting for the FedEX guy to deliver the POR-15. I'l post pics when I'm done.

Grind it all out then treat it and seal it up.

AZCA jeeper said:

Is it possible to do this on a unibody or is it too risky to mess with such a large section of it?

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You can replace large sections of unibodies with NO problem. They sell entire floor pans and replacement section of unibodies to be welded in. Most unibodies are NOT that precise, you can just fit the pieces together and weld them up.

Yea, I'm sure there are people that have screwed it up and their unibody was either weak (rattles/twists/creaks with bumps and motion) or mis-aligned (can't get a proper wheel alignment) but the overwhelming majority just repair the body by replacing the metal and welding it in and it works just fine, if they notice anything, its an improvement of a more solid chassis that doesn't rattle/twist/creak with bumps and motion.

I had a lot of rust holes, several very large ones in the floor pan. I just bought flat sheet metal from the hardware store of equal thickness and welded them up. I did use Body Sealant from NAPA to seal all the edges of the welds, inside and outside. Painted the entire interior floor pan with a hand brush and Rustoleum Paint. One hole went up the trans tunnel, I just shaped the patch with a ball paean hammer and welded it right in.

My XJ runs just fine, no more leaks in the rain and alignment, handling and tire wear is just fine, as well the chassis feels more rigid with bumps and motion.