Best way to restore the underbody of a car?

drobertson · Mar 14, 2017

I'm in the middle of the restoration of my 73 Charger, and I want to redo the underbody of the car before final bodywork and paint. From what I understand, it's best to take a heat gun & putty knife to remove leftover undercoating. But then what? I don't have any access to media blasting (life in wyoming.... town of less than 300 people, in the middle of nowhere...). Should I just sand down the underbody to bare metal? Prime it? Or just undercoat it? What products do y'all use and what's the preferred process?

When the car is finished it's only going to be driven during the summer, but I want to prevent any possible rust in the future. Thanks. - David.

dieseldazzle · Mar 14, 2017

Read jims 68 coronet build.

I use putty knife heat and media blast

He used aircraft stripper I believe

JimKueneman · Mar 14, 2017

It is within the first few pages so don't panic!

http://www.forbbodiesonly.com/moparforum/threads/1968-coronet-500-project.114333/

Superb Bee · Mar 14, 2017

Do you have a lift? I have done this, I would drop everything, tank, rear, trans, lines, cables, all plugs.
heat gun with scraper, then use this guy https://www.amazon.com/gp/product/B007TDFRI6/ref=ox_sc_sfl_title_2?ie=UTF8&psc=1&smid=ATVPDKIKX0DER to get it perfect.
then prime it and paint it body color. reassemble and call it restored.

Kern Dog · Mar 15, 2017

How nice do you want it?
Some cars were undercoated from the front wheels all the way to the rear bumper! That would make it easy if you wanted to replicate the look. You'd just clean the areas that had damage or flaking of the undercoat and reapply more of it. No car ever came from the factory with a fully painted floor pan. They were dipped in 2 vats of primer then sprayed with machines. The underside got paint at the rocker panels and whatever overspray found its way to the floor!
I liked the look of a painted underbody so I went overboard. I was lucky to have a NON undercoated California car that had very few engine leaks. I used Scotch Brites and tooth brushes along with "Castrol Super Clean" in a 3 gallon bug sprayer. The underbody was sprayed and scrubbed in warm weather and it dried quickly. I never primed anything... the floors were so clean I just fogged on the red enamel in several coats. The paint still is sticking...

dieseldazzle · Mar 15, 2017

Kern Dog said:
How nice do you want it?
Some cars were undercoated from the front wheels all the way to the rear bumper! That would make it easy if you wanted to replicate the look. You'd just clean the areas that had damage or flaking of the undercoat and reapply more of it. No car ever came from the factory with a fully painted floor pan. They were dipped in 2 vats of primer then sprayed with machines. The underside got paint at the rocker panels and whatever overspray found its way to the floor!
I liked the look of a painted underbody so I went overboard. I was lucky to have a NON undercoated California car that had very few engine leaks. I used Scotch Brites and tooth brushes along with "Castrol Super Clean" in a 3 gallon bug sprayer. The underbody was sprayed and scrubbed in warm weather and it dried quickly. I never primed anything... the floors were so clean I just fogged on the red enamel in several coats. The paint still is sticking...

View attachment 404558 View attachment 404559 View attachment 404560 View attachment 404561

You lucky **** head

Kern Dog · Mar 15, 2017

Want to cry some more?
March 12 2000, 17 years ago this week I bought the car for $1700 as a running, driving, currently registered car. I used it for work fora month while my truck was down. 130 miles per day!

Kern Dog · Mar 15, 2017

Deals like that are long gone. Yes, I was lucky and appreciate my blessing!

Richard Cranium · Mar 15, 2017

Just re-undercoat it again with some 3M spray cans.Having a mint undercarriage is a PIA and not worth the effort, unless you are creating a museum piece.

hunt2elk · Mar 15, 2017

If you do decide to remove the undercoating, a cheap small Harbor Freight needle scaler works very well.

1967coronet440 · Mar 15, 2017

I used an air chisel and needle scaler Set at about 40 psi and just knocked the undercoating off the sub frame rails then painted them black, sprayed over the existing undercoating to give it a new look.

747mopar · Mar 15, 2017

Kern Dog said:
How nice do you want it?
Some cars were undercoated from the front wheels all the way to the rear bumper! That would make it easy if you wanted to replicate the look. You'd just clean the areas that had damage or flaking of the undercoat and reapply more of it. No car ever came from the factory with a fully painted floor pan. They were dipped in 2 vats of primer then sprayed with machines. The underside got paint at the rocker panels and whatever overspray found its way to the floor!
I liked the look of a painted underbody so I went overboard. I was lucky to have a NON undercoated California car that had very few engine leaks. I used Scotch Brites and tooth brushes along with "Castrol Super Clean" in a 3 gallon bug sprayer. The underbody was sprayed and scrubbed in warm weather and it dried quickly. I never primed anything... the floors were so clean I just fogged on the red enamel in several coats. The paint still is sticking...

View attachment 404558 View attachment 404559 View attachment 404560 View attachment 404561

Very nice Kern!

747mopar · Mar 15, 2017

Richard Cranium said:
Just re-undercoat it again with some 3M spray cans.Having a mint undercarriage is a PIA and not worth the effort, unless you are creating a museum piece.

Couldn't agree more. I used a heat gun and scraper then media but knowing I'd be putting thousands of miles on mine I epoxy primed it and sprayed it all with Bedliner. Yes I'd love to put it on a lift and see the beauty like Kern's car but it would never last where I live and I never worry about it.

To answer your question, I found that paint remover and a power washer work great. You really need to wear full body rain gear and a face sheild because it will burn the crap out of you but it works very well. It may take a few applications to get it all off but it works wonders.

barbee6043 · Mar 15, 2017

years back I had a sand blast guy, he had a boon truck, he raised car up first front end, laid on his back and blasted the undersides, then raised the back end and blasted a way. $100. ok so it as 1995 and Missouri!!!!
I would clean off lose old undercoat and redo with gun for undercoating and spay a way. I also like undercoat called "body Schultz" and their gun. spray cans????? naw!!!

gkent · Mar 15, 2017

Before you go nuts buying air hammers, needle scalers or heat guns, try a plain old "sharp" scraper. The undercoating on my '69 RR has been coming off very easily that way. I'm not against heat BUT a) it smokes b) it stinks c) it burns when it falls on you d) it'll get stuck to your floor, shoes, etc and lastly e) because its melting it will leave residue behind which you'll have to clean off with thinners or something.

1967coronet440 · Mar 15, 2017

Looks a lot better than it did

Mike67 · Mar 15, 2017

Needle scaler works great on the areas that are hard as a rock and wont heat up enough to scrape. Also handy in the corners and on irregular shapes...

Bladecutter · Mar 15, 2017

dieseldazzle said:
Read jims 68 coronet build.

I use putty knife heat and media blast

He used aircraft stripper I believe

Yup, what i was going to say. Hot stripper to melt off the undercoat.
If there is no bad rust under, then prepping should be no nightmare,,, scuff **** down with 120 grit, spray piss coats of zinc over any bare metal & re-undercoat.
Make Sure All stripper has been neutralized & rinsed away from pockets, nooks, crannies

eldubb440 · Mar 15, 2017

no bigger pain in the *** than a painted underside, especially when dealing with original pans...........

Don selleck · Mar 15, 2017

i had a 67 barracuda went over it with a putty knife for the big boogers and wire wheeled the rest then 3m undercoat turned out pretty good took about two days

Best way to restore the underbody of a car?

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