Body Tub Prep

[rcmbronc]

I am currently sand blasting my tub. I have a few questions I am looking for answers to. This is a complete frame off so I want to do it right the first time.

1. What is a good way to remove old undercoating. Is there any chemical that will remove it, or should I use a torch and scraper.

2. I will need to change some panels after it is blasted (floorpans, kick panels, rockers). Should I prime the tub right after I blast it, or should I wait until I am dome with the panel replacement. What should I coat the new panel seams with as I am installing them? Also what should a person use for seam sealer on the seams in the tub?

3. I am planning on painting the underside of tub and inside with POR-15 and a topcoat. I don't think that primer type will effect this will it if I do immediately prime it. Is this right?

Sorry about all the questions, just have a lot of them as I get into this project.

 

[rflud]

After blasting my tub I had it a few coats of epoxy primer sprayed on. I figured that if I didn't rust would start to form right away, especially where ever you touch it with you bare hands (oil from your hands make it form rust faster).

I also had some body work to do after blasting it. The blasting allowed me to see everything that needed to be fixed.

So I vote blasting is a good thing and to shoot some primer on it.

 

[2badrotties]

If you sandblast the tub, spray some epoxy primer on it. PPG says that you can do bodywork right over DP primer and that filler will stick to the DP BETTER than bare steel. If you use POR 15 you will have to use their tie-coat primer over it if you plan on spraying any type of automotive paint over the por15. You do not need to sand the POR15 before you spray it with the tie-coat primer as long as you do it within a year %) so they say. The tie-coat primer is sandable so you could finish sand it before painting it with regular paint.
Don't use anything but urethane seam sealer althoughI hear that POR make some good seam sealer. I have never tried it. I prefer the urethane because it will flex with the body ( metal moves around in different weather ).
Kerosene and rags will take the undercoating off but don't have a cigarette while you are doing it ;D .

I am redoing a bronco right now too. I'm not getting carried away with it though. I'm just building a nice clean driver. I didn't blast the underside of my tub. I'm going to wire brush it , POR it, and cover it with black undercoating. If you have the time to check out my web pages you might find some useful stuff.
Click here ... www.2badrotties.classicbroncos.com good luck with yours.

 

[brutis72eb]

I am doing the same thing. I would suggest doing all your sheetmetal work before you get it blasted. Then your body will be completely ready to start the body work after it gets back from the blaster. And your not having them blast something that is just going to be cut out anyway. Then shoot (or have someone shoot) primer (like 2bad said). I recommend this first because you have to shoot your bronco with something or it will start to rust almost immediatly if you let it sit without a coat after the field trip to the blaster. As far as seam sealers stick with 2bad's suggestion. Are you blasting the tub yourself?? I just read that, sorry, wont the old undercoating come off with the blaster?

 

[rcmbronc]

I am blasting it myself. The undercoating really comes off hard with the sandblaster and some wont come off. I sandblasted a bunch and am now going to scrape off as much undercoating as I can. Then I will go back and finish sandblasting. I also noticed some panels that need replacing, so I will remove these before I finish blasting. This is really the worst part of this project. I am sick of sand.

2Bad, your truck looks great. You are obviously are a good body man. I am not good at it, but I am going to try to learn to finish this project. Do I just go down to the auto store and ask for an epoxy primer? I have a HVLP gun and made a paint booth in my shop for spraying. Can this primer be welded to, or do I have to scuff it away near my welds for added floorpan etc.

Thanks again.

 

[brutis72eb]

Ok, I see what your saying now. I was thinking of blasting myself but for the time and energy it takes I thought it would just be easier to get it done perfessionally. And you dont have to worry (as much) as sheetmetal warping as opposed to if you were doing it yourself. Just my 2 cents. Good Luck and Happy Blasting!;D

 

[MnkyBiz]

For scraping off the under coating, I have come to love my Goodell painters scraper! See attached photo (sorry, I am not the graphics designer!!!)

This is a great tool, as the end is metal that is connected to the body of the scraper! It allows you to hit it really hard with a 5lb hammer!!!! I have used this from scraping under body sealant, to splitting spot welds!

This gets my vote for tool of the year!!!!!

Monkey Biz!

 

[brutis72eb]

I use those at work as a case splitter but if you keep those sharp they are mean! That would work really well!

 

[HotWheels]

I blasted mine also. I waited until I had my new sheetmetal in then blasted. por-15 is enough of an undercoat for me or I would have line-x'd it underside too. It is currently getting line-x inside. No, I did not por-15 before the line-x as it was fresh sandblasted interior. Line-x should keep rust from ever appearing. I will post some photos as it get's done. If you have ANY questions just ask.

check out my thread:


http://classicbroncos.com/forums/showthread.php?s=&threadid=41140

 

[HotWheels]

u can blast off undercoating. I did. mine was hard and not rubberized.

 

[brian72]

...You do not need to sand the POR15 before you spray it with the tie-coat primer as long as you do it within a year %) so they say. The tie-coat primer is sandable so you could finish sand it before painting it with regular paint.

I was curious about their primer so I went lookin and their website says," It may be used over well-seasoned POR-15 coatings even if they are more than a year old, with no special preparation other than cleaning the surface."

 

[HotWheels]

yup very good stuff.