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Author Topic: Bucket List Project (72 Challenger)-How do I protect metal?  (Read 274 times)

Offline SlyGuy

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Bucket List Project (72 Challenger)-How do I protect metal?
« on: April 01, 2017 - 11:22:31 AM »
Hello all, I am making slow progress on the Challenger. As I post new pictures, please keep in mind that everything I do on this project is a first for me, including welding. I am just about done with patching the front drivers side floor pan and left half of the firewall. My question is about treating the new and the old metal. What process, and what products should I use? Is there something I can use to treat for future rust that will also prep the new/old metal for paint? Or are rust prevention and paint prep two different things? I also need to treat the engine compartment, front frame rails, and inner fenders. There is a lot of surface rust, but otherwise these areas seem pretty solid. Any input or advise is appreciated. Thanks, SlyGuy
« Last Edit: April 01, 2017 - 11:51:43 AM by SlyGuy »




Offline 4 speed fish

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Re: Bucket List Project (72 Challenger)-How do I protect metal?
« Reply #1 on: April 01, 2017 - 01:38:42 PM »
I would get the car blasted and then epoxy primed.I would blast the shell and have the other pieces blasted as you need them.

Offline Rich G

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Re: Bucket List Project (72 Challenger)-How do I protect metal?
« Reply #2 on: April 02, 2017 - 09:01:50 AM »
You could wipe it down with a metal prep and that will protect it from flash rust for a little while but the epoxy primer is your best bet.


Online Beekeeper

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Re: Bucket List Project (72 Challenger)-How do I protect metal?
« Reply #3 on: April 02, 2017 - 10:57:57 AM »
I'm doing something similar on my car. I plan to blast the whole car when done. The areas that will never see light again cannot be blasted, like inside rails under the floor. What I am doing there is cleaning and painting with KBS rust paint. its not pretty but since it's inside areas that can never be seen, I'm am only concerned about protection and stopping surface rust from getting worse. On the other areas that are open like the firewall, if you do not plan to blast, you really need to get all that surface rust out before painting. The KBS product can be sanded and primed/painted so that's another option. I helped a friend do this to his Charger in the engine compartment and we finished it with body color. It looked great but I wonder if it will be a lasting solution. So far so good.

If you are able to get all the surface rust out of the nooks and crannies, you will want to shoot it all with a good sealer. They make sealers that can go over bare metal and they totally block out different panel colors to hide what's underneath. I think the epoxy primer that was recommended is also referred to as a sealer but I'm not sure. If you have an auto paint supply place near you, they can help you make the right product selections so you get the job done right with no compatibility issues. I did this and those guys were fantastic at helping me select the right stuff as well as giving good advice on how to use it.

On another note, hard to tell in the photo but it kinda looks like you are overlapping metal in the floor pan. If you do, make sure to put a good sealant in the joint. These cars always develop rust in areas where metal overlaps other metal.

Good for you taking on a project like this! It's very satisfying doing it yourself plus the labor savings makes your budget go a heck of a lot further.

Offline SlyGuy

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Re: Bucket List Project (72 Challenger)-How do I protect metal?
« Reply #4 on: April 04, 2017 - 07:33:52 PM »
Hey guys, thanks much for the input. Sounds like I need to learn about epoxy primer and sealant. And thanks to Beekeeper for the tip about overlapping metal. I'm sure that 90% of what I do on this will not be "by the book" so to speak. My poor Challenger is the ultimate guinea pig, but I'm determined to do as much myself as possible. So, the sand blasting has been the white elephant in my garage since day one. I don't have the equipment myself, and the car is on jack stands. If I put the necessary hours in with the wire brushes, do guys think I can still get a decent finish on the shell? Also, one last question about treating the metal: I have read a few posts where guys talk about using POR-15. Can you tell me what is POR-15, and is it a good option for me? Thanks again!

Offline glovemeister

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Re: Bucket List Project (72 Challenger)-How do I protect metal?
« Reply #5 on: April 04, 2017 - 09:42:44 PM »
In a situation like yourself. Your pictures look just like what my car looks like. I am not expert and am going through my first restore with common tools.

I have no acid dipper local, I have no sand blaster local, and I also don't have  a large enough compressor to do it myself. I've considered renting a large diesel compressor and doing it that way in a weekend, but that's another story.

Forget all the magic stuff you hear about namely POR-15. It works well, but is attracted to rust and is not the best top coating for anything other than frame rails or hidden areas. Basically if you get down to clean metal and use Por-15 its not smart.

 Also do not under any circumstances use Wd-40, or any silicone based lubricant to protect metal. You may have some guys tell you to use Wd-40 to wipe down a panel to keep it rust free. That is silly and a surefire way to open a big potential failure of your paint system down the line. If you clean it 100% you are probably fine, but who wants to run the risk of a perfect paint job to fail over a move that isn't necessary.

You should do the a section at a time and spray it with a suitable epoxy primer, I use SPI Epoxy, because it has phenomenal reviews and is affordable.

I've tried to strip the whole car down to bare metal and get to epoxy, but I just couldn't get it done quick enough and was chasing my tail. So now I will pick an area, say the inner firewall/aprons. Over a weekend I will get it all cleaned to bare shiny metal, fix anything if I need to, and get it cleaned and in epoxy.

For areas with larger rust I take the same approach, but don't focus much epoxy on the rust/corroded metal. I work on that repair as I can and then epoxy the whole panel.

My plan when I am done doing it section by section is to spray the entire car with fresh epoxy.

Anyway that is one way for a guy with limited tooling and limited local sources that is tired of chasing his tail on surface rust.
 
1971 Challenger RT

Online Beekeeper

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Re: Bucket List Project (72 Challenger)-How do I protect metal?
« Reply #6 on: April 04, 2017 - 09:53:43 PM »
I don't know much about POR 15 but I've noticed some guys complain that it's too difficult to work with later. Check out KBS coatings. I liked what I read and gave it a try. I know from experience now that it can be sanded down and painted over without too much trouble. It also sands off easily from areas if you make a mistake. I hear POR 15 is awful to remove later if you need to.

I think you will be okay with wire wheel cleaning everywhere else if you coat it with the right product afterward. On exterior areas that everyone sees, I'd put extra effort into getting every bit out though. They do make small portable sand blasters which might be an option for some small rust pitted area. Wouldn't do a whole car but it might do for say a roof that is pitted from a vinyl top.

Offline glovemeister

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Re: Bucket List Project (72 Challenger)-How do I protect metal?
« Reply #7 on: April 05, 2017 - 12:30:33 PM »
I forgot to mention. I like to wire wheel a section down ( I'd be careful on panels with little definition, as the heat can warp them. I would look into the plastic bristle discs). Then hit it with some 80 grit sand paper, as that is speced by my epoxy. Reasoning is that wire wheeling basically smooths the surface pits, and the 80 grit gives the primer some mechanical tooth, inline with the epoxy tech sheets.

Has been working well so far.
1971 Challenger RT

Offline PLUM72

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Re: Bucket List Project (72 Challenger)-How do I protect metal?
« Reply #8 on: April 21, 2017 - 04:21:33 PM »
Figure out the epoxy primer thing.  This can be purchased locally or various places online.  If yo don't already have one, buy an air compressor.  Then buy an inexpensive paint gun from harbor freight.  Strip what you can chemically with aircraft stripper, sand down the rest with a DA sander, electric works fine.  Then if you have rust, get a suction feed sandblaster.  This works off the air compressor.  Blast those rusty spots or spots you cant get with the chemical stripper.  Epoxy prime those areas that were stripped/sanded/blasted right away so they don't flash rust.

Work your way around the car little by little.  A door one day, fender the next, etc.  Before you know it, it will all be in primer.  You can then go back and do any hard core metal work needed again little by little; priming after you're done.  Don't use rust  transformer products especially on the outer body.  Blast or cut away the rust.  Who will do final body and paint work?