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Old 03-27-2012, 08:18 PM
moroza moroza is offline
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Frame paint ideas; thoughts?

I've been doing lots of reading about paint, and a lot of the most informative posts came from this forum, so that's why I'm here. I want to paint my truck's frame for rustproofing. I don't much care how it looks, I care about it being physically and chemically durable for a long time. This is a 4x4 that'll see all kinds of dust, rocks, ice, snow, salt... everything a vehicle could possibly encounter, and I won't be able to touch-up or even wash it for months at a time: it's going to be a motorhome that I might be full-timing in once it's built.

Budget? $150 would be nice, $250 acceptable, $500 absolute maximum.

Here's my idea for the outside of the frame:
1. Strip to bare, shiny metal with wire brushes, no chemicals.
2. POR-15 Metal-Ready, followed by the black POR itself, brushed or rolled on, not sprayed (I have a compressor, but also neighbors who'll have my head if I stink up the place. Plus, I hear that POR in particular has some real toxic vapors if sprayed).
3. Epoxy primer, also rolled or brushed on.
4. Tractor/implement paint topcoat with added hardener, also brushed/rolled.

Specific question: can I do something less drastic than a down-to-bare-metal strip, without sacrificing primer and paint adhesion quality? I have no idea what my frame's factory paint is. It's a 1981 Toyota pickup.

Here's my idea for the inside:
1. Put the frame on a rotisserie, pressurewash the inside with diluted degreaser, rinse and dry thoroughly, possibly a couple of times.
2. Weld up or otherwise permanently seal 90% of the holes in the frame, mostly the small ones.
3. Make bolt-on covers with rubber gaskets for the remaining holes. Add an air fitting to one of them. Test the whole frame for airtightness (including +/- 10 psi or so, to allow for temperature-related pressure changes) until it passes.
3.5. Make the assumption that air-tight means water-and-all-other-crud-tight.
4. Pour in some oil, rotate the frame every which way to spread it, drain the excess.
5. Throw in a few dessicant packets (little white baggies in snack food packaging that say "DO NOT EAT"), bolt on the covers, inspect once a year or two but expect it to never rust, at least not from the inside like truck frames usually do.

Corrolary ideas for the inside:
- Suck out about 10psi of air before sealing it up, to help against moisture and pressure increases from heat.
- Leave one or two holes open, install vents in them (like axle housings have), possibly run hoses from them up high to allow water crossings.


Last edited by moroza; 03-27-2012 at 08:28 PM.
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