Author Topic: Easiest way to clean\paint underside of car.. (Read 10968 times)

DodgeFreak · « **on:** September 20, 2004 - 11:15:44 PM »

ok...some idiot sprayed some rubberized undercoating all over the underside of the car...(great for keep rust and what not off pain in the butt to remove) and suggestions on how to remove it...i started takeing it off by heating it with a small propain torch and the scrapping it off...works ok but need something that will take it off faster...then whats the easyiest way to paint it?? with out a rotissarie? thanks.

BIG MIKE · « **Reply #1 on:** September 21, 2004 - 02:28:07 AM »

try gas and paint thinner. i know gas will take some undercoatings off..

Steve · « **Reply #2 on:** September 21, 2004 - 04:32:33 PM »

Gee, you don't want much, do you?

I used an acetalyne torch to heat up the stuff and a large scraper to scrape it off.

It might be worth trying to find someone with a lift or a pit to work on/over.

The real pain will be prepping the underside for primer/paint. The correct (if that matters to you) underside treatment is to prime with a grayish primer (some magazines have published the color code). There will be some overspray of body color on the underside near the sides of the car. Prepping, at a minimum, involves scuffing with scotchbrite or 180 grit and wiping down the surface with wax remover. If you don't prep properly, whatever you spray on (except more undercoating) is just going to peel off in short time.

I just thought of a rig that attached to your wheel hubs that allows you to tilt the car over. That might be a solution to your situation. Off course, it might be cheaper to pick up 2-post lift.

Just some thoughts....

DodgeFreak · « **Reply #3 on:** September 21, 2004 - 06:52:00 PM »

what if i sand blasted the underside?

because i've already have a mess of dust and what not from sanding on the roof and out side...so whats a little well alot of sand gonna hurt if i clean the inside out well...by blowing\sweeping\wiping it out??? i mean sand blasting after i have the undercoating off.. $:-\$

Street_Challenged73 · « **Reply #4 on:** September 21, 2004 - 08:55:51 PM »

Try a wire wheel hooked up to a 4 1/2" angle grinder.......That's what I did to my underbody before I sent it off to a sandblasting shop....That seemed to do the best work for the amount of time I had invested in it.

torredcuda · « **Reply #5 on:** September 22, 2004 - 06:15:44 AM »

Sandblasting works good and goes pretty quick but makes a huge mess.Be prepared to spend a lot of time blowing,vacuuming/sweeping it out and you never seem to get it all.

HemiDog · « **Reply #6 on:** September 22, 2004 - 09:08:40 AM »

I am still finding pockets of media after having my car media blasted. Once I got the car back, I spent several hours trying to blow all of it out that I could. I do have a lot of patches to do and standing back and looking at the whole picture, I think that fact definitly helps to get all of that stuff out.

The main areas that seem to hold pockets of media are the rocker panels and frame rails (front and back).

Plum6Pak · « **Reply #7 on:** September 22, 2004 - 04:24:52 PM »

I sandblasted my engine compartment and front end and got the sand everywhere too. I blew out what I could then took my shop vac and taped a small enough hose on the nozzle to put into the frame rails and it got a lot of sand out that I couldn't blow out with my air nozzle. Just an idea that worked for me.

DodgeFreak · « **Reply #8 on:** September 23, 2004 - 08:44:05 PM »

sounds like alot of people sandblasted their cars...i'm going to try and get alot of the undercoating off with a wire wheel then sand blast to make sure i get everything clean then wipe it down with paint thinner or something to get the oil off...am i on the right track?

Street_Challenged73 · « **Reply #9 on:** September 23, 2004 - 09:09:15 PM »

That sounds like a good plan, but I'd do one thing different. Try applying the Acetone to the undercoating before wire wheeling it all off. That way you're softening up the underbody goo so the wire wheel will cut right through it quicker. As a heads up, that goo will gum up your wheel a few times and most likely clean it off in one area and redeposit itself somewhere else. However, at least it's broken up enough for the sandblasting media to finish getting the rest of it off.......Whatever you do, don't put any sort of liquid on the freshly sandblasted metal or else you'll get some serious flash rust. Then you're starting back at step three and that's never good to go backwards in your progress.

I'd suggest getting whatever patching you want done shortly after getting it blasted, then follow that all up with some expoxy primer right away. Hope this gives you some help towards the right procedures.

1973challenger360 · « **Reply #10 on:** September 24, 2004 - 08:03:48 PM »

putting chemicals on undercouting then wirewheeling it sounds good but be properly protected especially on your head eyes ears.

Plum6Pak · « **Reply #11 on:** September 25, 2004 - 08:59:06 AM »

You will have quite a fire hazard there using any of those things on the underside to soften it up. The gas would be the worse, make sure you have real good ventelation and NO sparks! Sand blasting is going to be the safest and if you want to wire wheel it first the best you can that will help but a good sandblaster will take it all of regardless. Just be careful, a lot of people do things that they think will be real helpful and speed things up and then end up in the burn unit.�

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GreenFish · « **Reply #12 on:** October 02, 2004 - 07:45:44 AM »

someone undercoated my engine compartment. I got it off with a pressure washer. Although i wouldt recommend that for the whole underside. it did a good job and clean up was a snap.. (its water) but it only does small areas at a time.

DodgeFreak · « **Reply #13 on:** October 03, 2004 - 09:49:21 PM »

I was thinking about taking the car into where my dad works and gettin it up on a lift and then using the hottsy(SP?) powerwasher on it..it would take it off...but i'm going to try to sand blast it..we have a 10 gallon pressurized sandblaster...i'm gonna try...

miketyler · « **Reply #14 on:** October 04, 2004 - 07:11:49 AM »

I would try the power wash method first. If you can, get one of the heavy industrial units with heated water and 3500 PSI. I am not familiar with the undercoating products and dont know how well they bond. Maybe large build ups will peel off if they didnt properly clean the bottom side before they undercoated it. I passed on a 70 model that was here in Dallas just for that. They had undercoated EVERYTHING including the bottom of the transmission, the rear end, etc. It looked really bad and made me think they were trying to hide something.

Also, if you do go the sandblast route and it doesnt take off the material you might try different media, like walnut shells. Maybe some places near you that will do this for you fairly cheap. It makes a helluva mess

Author Topic: Easiest way to clean\paint underside of car.. (Read 10968 times)

DodgeFreak

Easiest way to clean\paint underside of car..

BIG MIKE

Re: Easiest way to clean\paint underside of car..

Steve

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DodgeFreak

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Street_Challenged73

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torredcuda

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HemiDog

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Plum6Pak

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DodgeFreak

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Street_Challenged73

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1973challenger360

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Plum6Pak

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GreenFish

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DodgeFreak

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miketyler

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