Advice for this frame rust?

AussieNick

AussieNick

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I dropped the transmission cross member / skid plate and discovered this rust, only around the 3 bolt threads on each side. There is pretty much zero rust in the rest of the car so this is disappointing.

From my search it seems like a common problem? Is there a common solution and even more hopefully a simple solution?

Is the washers-between-frame-and-crossmember the recommended long term fix?

Thanks.
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ncfitton said:
I dropped the transmission cross member / skid plate and discovered this rust, only around the 3 bolt threads on each side. There is pretty much zero rust in the rest of the car so this is disappointing.

From my search it seems like a common problem? Is there a common solution and even more hopefully a simple solution?

Is the washers-between-frame-and-crossmember the recommended long term fix?

Thanks.
Click to expand...
First thing I would do is remove what rust is there with a wire brush or Scotch-Brite to see how deep the rust actually goes...
 
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Clean it up and paint it. Remember that the inside of the frame is all that matters. The outside is not a problem at all. Check the inside very very thoroughly to see if there is really anything to worry about.
 
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ncfitton said:
I dropped the transmission cross member / skid plate and discovered this rust, only around the 3 bolt threads on each side. There is pretty much zero rust in the rest of the car so this is disappointing.

From my search it seems like a common problem? Is there a common solution and even more hopefully a simple solution?

Is the washers-between-frame-and-crossmember the recommended long term fix?

Thanks.
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Click to expand...

I would hit the rust with a Metabo and wire wheel down to bare clean metal. From the pictures it appears to be surface rust in the usual places. Removing the rust will give some indication of how deep the rust goes. I would get a cheap bore scope from Amazon to look inside the frame in that very area. There is an excellent article on cleaning the inside of the frame on this site.
 
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You can see where there are pin holes going through in the picture. Before cleaning and painting, beat on the area with a ball peen or another type of hammer with a pick end might be even better to see if the metal is thin. You should not be able to punch through the frame. If you can, the area needs to be repaired. From the holes that can be seen, I would guess you will find the metal quite thin. Check the rest of your frame while you are at it. Particularly where it sweeps up in the rear as there are no drain holes. Check your rear spring perches also.

Safety Cap is one brand that can weld in after cutting the area out. They make sections for just the pan bolt area, other areas or the whole frame. There are other brands out there as well. You will need to be able to cut and weld to do this. If not you need a local shop to do it.

Hey, if it's not that bad weld a big patch around the threaded hole and consider it a 1/4" transfer case drop!
 
Judging by these photos, worst case, you’ll need center safe-t-cap rails. Its incredibly common for TJ’s. Metal on metal in any salted areas or wet environments is bad news, which is why I sandwich Fluid film or some type of wax in between those two spots. Also why I refuse to buy armor that butts up against the tub of the Jeep.

As others have mentioned, the rust often kills from the inside. Feel in the frame holes for piles / chunks of rusted metal. That’s something that also needs addressing.
 
I think it’s just surface rust. I used a wire cup on my angle grinder and then tapped on the frame with a hammer/punch as suggested. It feels solid.

Most of the ugliness is weld spatter. Is that how it comes from the factory or did a previous owner already repair this once?

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People bringing up safety caps and other repairs because of minor external rust...

If the inside feels smooth, you are fine. Remember that the inside is all that matter. Really, external rust on TJ frames is never a real problem.
 
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"Overhead" welding is somewhat of a challenge. Those welds aren't the best looking things I've seen, not even average really, but they must be good enough to hold the nutserts in place. Get them and the skid plate painted and you should be good to go. I'd probably spray some Fluid Film on it all before bolting it back up but where I live I'm surrounded by rust.
 
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