Cleaning frame and underside for paint

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selkplitt
Posts: 11
Joined: Fri Nov 09, 2012 7:30 am

Cleaning frame and underside for paint

Post by selkplitt »

I am cleaning the underside of the 89 GW to prep it for Eastwood rust encapsulator and chassis black in satin. I have the fuel tank out and am replacing the rear suspension, shocks, brakes and drums, new steel brake lines. The frame is great with no rust in the fuel tank area other than some surface rust as is most of the under side. But I was surprised to find that all the leaking oil kept the floor area back to the rear suspension pristine. All of a sudden I don’t think I should be chasing all the leaks and let them take care of the rust proofing
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89 Grand Wagoneer bone stock
07 Commander 4.7 Rocky Mountain QDII
18 GMC Canyon Denali 2.8 diesel

candymancan
Posts: 3652
Joined: Tue Mar 22, 2016 11:32 pm

Re: Cleaning frame and underside for paint

Post by candymancan »

Your first thing is to get a decent sized fan to blow all the rust dust out when youre down there.

Then you gatta get yourself a good n99 or p100 respirator. And i would go to town with a angle grinder and start grinding the rust away as best as you can. A wire wheel isnt going to do jack to that. You gatta grind that thick pitted rust off as best as you can. Unscrew the brackets for the fuel and brake line all the way back to the drivers seat and move them to the passenger side as best as you can.. if you remove the brackets that far back they move easily. Same with the wiring. Unhook it and pull it away and zip tie it off somewhere so its all outa the way

I just did this to my 90. But my frame was worse i had to cut out the rot and weld in a new peice. But i also ground down the other rust elsewhere. I used 4 coats of rust reformer myself.

Ive used this paint for years. Its pretty good stuff.

https://www.fsjnetwork.com/forum/viewto ... 10&t=19147
1998 Jeep Grand Cherokee 5.9L Limited 219k
1998 Jeep Grand Cherokee 4.0 I6 laredo 430k
1990 Jeep Grand Wagoneer 155k
1976 Jeep J10.. 85k(repaired)
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HowardT64
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Joined: Sun May 05, 2013 2:47 am
Location: Athens,Texas

Re: Cleaning frame and underside for paint

Post by HowardT64 »

looks like a lot of work...but I bet the results will be awesome :)
2016 Jeep Patriot
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GrandJoshoneer
Posts: 36
Joined: Fri Mar 06, 2020 5:26 pm

Re: Cleaning frame and underside for paint

Post by GrandJoshoneer »

I did the same thing to mine. It had surface rust here and there, so I started in the very back and worked my way forward. Knocked everything back with a wire wheel, cleaned it and coated everything with corroseal. Since it is also a primer, I sprayed it with rustoleum metallic, and black on the frame. Then hit some areas with Fluid Film, especially the inside of the new rockers. The closer I got to the front, the less I did. No sense in removing all that oil and grime since it’s doing me a big favor.
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1987 Grand Wagoneer

threepiece
Posts: 430
Joined: Mon Apr 20, 2020 8:33 am

Re: Cleaning frame and underside for paint

Post by threepiece »

candymancan wrote: Mon Sep 21, 2020 10:42 am Your first thing is to get a decent sized fan to blow all the rust dust out when youre down there.

Then you gatta get yourself a good n99 or p100 respirator. And i would go to town with a angle grinder and start grinding the rust away as best as you can. A wire wheel isnt going to do jack to that. You gatta grind that thick pitted rust off as best as you can.
I like the recommendation of a respirator but the grinding has me shaking my head.

A grinder doesn’t discriminate. It will remove rust and the precious metal at the same rate leaving you with a weaker frame than before. If sandblasting is not an option than a stiff twisted wire wheel and metal prep is a much better way to go.
I used to name my FSJ’s after their previous owners, I realized I had too many with five named Rick.

Dang raccoons again!

Rust is a color too.

weeegoneeer
Posts: 230
Joined: Wed Apr 26, 2017 10:34 am

Re: Cleaning frame and underside for paint

Post by weeegoneeer »

+1 on the wire wheel. It does remove metal but is more controllable, conforms to the surface, and you still get down to bare metal. Not a pro by any means, just have had luck using this approach.
1984 GW

threepiece
Posts: 430
Joined: Mon Apr 20, 2020 8:33 am

Re: Cleaning frame and underside for paint

Post by threepiece »

Five tools I found most effective for doing this type of work are:

1- angle grinder
2- inline or straight grinder
3- twisted wire wheel brush
4- twisted wire cup brush
5- flood light

With these five one can clean the majority of a frame fairly quickly. The brushes can be swapped to either grinder. The smaller electric grinders will get hot doing this type of work, that is when I switch to a different grinder while the other one cools (or lately I just take a break). I like a hand held sand blaster for the tight spots. These have an integrated cup and are about the size of a spray gun.
I used to name my FSJ’s after their previous owners, I realized I had too many with five named Rick.

Dang raccoons again!

Rust is a color too.

candymancan
Posts: 3652
Joined: Tue Mar 22, 2016 11:32 pm

Re: Cleaning frame and underside for paint

Post by candymancan »

threepiece wrote: Wed Sep 23, 2020 7:06 am
candymancan wrote: Mon Sep 21, 2020 10:42 am Your first thing is to get a decent sized fan to blow all the rust dust out when youre down there.

Then you gatta get yourself a good n99 or p100 respirator. And i would go to town with a angle grinder and start grinding the rust away as best as you can. A wire wheel isnt going to do jack to that. You gatta grind that thick pitted rust off as best as you can.
I like the recommendation of a respirator but the grinding has me shaking my head.

A grinder doesn’t discriminate. It will remove rust and the precious metal at the same rate leaving you with a weaker frame than before. If sandblasting is not an option than a stiff twisted wire wheel and metal prep is a much better way to go.

Frame is 1/8 inch thick youre not going to remove much metal.

Just grind enough of the crusty rust off. The problem with wire wheel is they polish the metal.. including the rusty chunky metal and it leaves the chunky peices on there. Meaning chunky stuff you dont see will be polished but have rust underneeth it.

Trust me. Ive been dealing with rust for 4-5 years on my wagoneer 100x worse than yours. A wire wheel has its uses but only for the very light rust yours a bit deeper than that.

Im not saying to dig deep with the grinder.. just get it shiney. Takes only a second.

Like in my picture on my post. I linked. Do you see me grinding it down to paper ? No i just got it till its shiny and clean. The pitting you see deep down dont worry about with the grinder thats where you use the wire wheel. Just get the crusty stuff off with a grinder.

See this pic. This is my donor peice i was lining up to my frame. And see how i cleaned it up ? Just go up and down up and down with the grinder dont hold it in one spot forever.. itll grind the rust off and leave 99% of the good metal there.

But if youre too scared to do it. Then use a wirewheel.. its up to you. But as you can see i didnt make anything thin

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1998 Jeep Grand Cherokee 5.9L Limited 219k
1998 Jeep Grand Cherokee 4.0 I6 laredo 430k
1990 Jeep Grand Wagoneer 155k
1976 Jeep J10.. 85k(repaired)

threepiece
Posts: 430
Joined: Mon Apr 20, 2020 8:33 am

Re: Cleaning frame and underside for paint

Post by threepiece »

It looks like you changed your positions here candyman. I agree with everything you describe here in your last post. It is in your first post “going to town with an angle grinder“ and “grind the thick pitted rust off as best you can” that I disagree with.

I do all my rust removal by sandblast. It’s a messy, uncomfortable affair but the results are worth it to me. The bonus is if the proper media is used no further surface preparation is needed.
I used to name my FSJ’s after their previous owners, I realized I had too many with five named Rick.

Dang raccoons again!

Rust is a color too.

candymancan
Posts: 3652
Joined: Tue Mar 22, 2016 11:32 pm

Re: Cleaning frame and underside for paint

Post by candymancan »

threepiece wrote: Mon Sep 28, 2020 8:14 pm It looks like you changed your positions here candyman. I agree with everything you describe here in your last post. It is in your first post “going to town with an angle grinder“ and “grind the thick pitted rust off as best you can” that I disagree with.

I do all my rust removal by sandblast. It’s a messy, uncomfortable affair but the results are worth it to me. The bonus is if the proper media is used no further surface preparation is needed.


I didnt change anything. You just over analyzing things. Grinding the thick rust off involves you moving the grinder up and down how is that changing my stance.

Do whatever the heck you want. Im just showing and telling how i did it. A grinder is way cheaper than a sand blaster. And i dont take much metal off. Considering how my frame looked like swisss cheese with holes and with bread crumbs falling off i dont care what slivers of metal i did take off from grinding a more solid donor peice clean.
1998 Jeep Grand Cherokee 5.9L Limited 219k
1998 Jeep Grand Cherokee 4.0 I6 laredo 430k
1990 Jeep Grand Wagoneer 155k
1976 Jeep J10.. 85k(repaired)

threepiece
Posts: 430
Joined: Mon Apr 20, 2020 8:33 am

Re: Cleaning frame and underside for paint

Post by threepiece »

candymancan wrote: Tue Sep 29, 2020 1:48 pm
You just over analyzing things.
Indeed, anyone that knows me would agree however I will accuse you of the same.

My response was not directed at you. It is obvious looking at your recent repairs that you have a good grasp of what needs to be done and how to do it. I had nothing to offer you in advice and I applaud your tenacity. I was trying to prevent a beginner from borrowing their uncles 12 amp grinder with a 24 grit, paper backed disk and "going to town" with it. a set-up like that can do a bunch of damage in short time, especially in the hands of someone who has pyromaniac tendencies. It happens too often.
I used to name my FSJ’s after their previous owners, I realized I had too many with five named Rick.

Dang raccoons again!

Rust is a color too.
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