Just finished stripping my '81 down to the bare frame this weekend, have a few questions related to powder coating the frame, control & trailing arms, radiator frame/bracket, etc. that I hope I can get some guidance on.

1. For any threaded holes, should I leave the screw/bold screwed in to protect the threads? or run a tap through them later to remove any excess powder coating that may have entered the threaded holes?

2. Should I tape off the mating surfaces between the trailing arms and rear hub assembly prior to powder coating to insure a tight metal to metal mating when I reassemble them?

3. Anyone have problem re-installing the radiator frame after powder coating? Mine was a tight fit when taking it a part.

4. I'm planning on using Eastwoods Internal Frame Coating (w/Zinc) inside the frame rails:

4a. How should I clean out the insides before coating? Pressure washer? air?
4b. Should I clean and coat he inside before or after the frame gets media blasted and powder coated?

5. Any other suggestions?

Many thanks.

 

How did you strip it?

 

Sure you know most of this, but will offer my experience.

1. Ensure all rubber and plastic parts are removed.
2. Prior to blasting the outside of the frame, go buy a couple gallons of phosphoric acid and put it in a garden pressure sprayer (the kind you hand pump up the pressure).
3. Use the long wand on the sprayer and spray the inside of every hole and nook in the frame. You can even hook on a long rubber fuel hose and get it in to deep spots.
4. The PA should be flowing out of every crack. This stuff will kill any rust it contacts.
5. Now sand blast the outside of the frame.
6. Use the plastic powder coating plugs in all the threaded holes and powder coating tape on any areas you do not want coated.
7. Several PC guys will then spray the outside of the frame with the same Phosphoric Acid, put the frame in the oven to burn off oil and grease, and get it completely dry. The Phos Acid will leave funky streaks on the metal, but that does not harm the PC at all...in fact, it helps prep the metal for the PC. You then pull the frame out of the oven and PC it, back in the oven and done.
8. After the frame is PC'd, then go buy a quart of black restoleum flat black and put it in your garden sprayer with another quart of thinner. The thinner will make the paint thin enough to spray through the garden wand.
9. Do the same thing to the inside of the frame that you did with the Phos Acid. Spray every hole and every nook until the paint is running out. Just have several rags ready to wipe off the paint that runs out.
10. You cannot do the inside paint until after the PC is complete because the frame will be around 425 degrees when baking the PC.

Where are you at? I have a nice drive-in PC oven and industrial sand blaster...you could do it all yourself if you are close to Montgomery Alabama.

 

sorry, when I said strip it, I was indicating that I've removed all the suspension, parts, etc. down to just the frame. Have not blasted it yet or removed any paint, rust, etc. Frame is in great shape with some surface rust here and there.

Thanks

 

I was wondering because how it was stripped may change the way you treat the frame tubes.
If you sand blast it, it will be faster with a more aggresive sand grit however the surface may be a little more ruff than you'd like. Or after the blast, you could whizzer wheel the surface areas.
On mine, I POR15ed the entire deal with three coats. The tubes can be sprayed, or what works is feed 550 cord through the areas with holes at each end and tied a sponge to it. soaked the sponge in POR15 and pulled it back and forth until I had a good coating. Two coats of the POR and I didn't use the chassis black inside the tubes.
Around the trailing arms, I wouldn't go thin, as it may lead to a rust break through later on. I'd maintain thickness and adjust shims accordingly. I doubt you'll need to be concerned in that area.
The threaded holes, I run a tap through them anyway so I leave them exposed.
Post pics as you go along. Many like watching your progress. I know when I get stalled seeing someone else making progress helps get me motivated.

 

I believe my offset trailing arms from VBP were completely powdercoated, with no taped off sections. I had my frame, trans crossmember (which I changed and is now a Bowtie Overdrive crossmember, also powdercoated red, for my T56 6 speed), fuel tank crossmember, and rad support acid dipped and powdercoated red. After the powdercoating, I had no problems with anything fitting due to the paint, went over all the threads with a tap, and coated the inside of the frame with Fluid Film to protect it from rusting. Good choice with the powerdercoating! Are you going with black or another color? Here's a pic I took the other day under the back end. Also, I beefed up the frame by going over all the welds, adding gussets, and boxing the front of the frame rails before sending it out for powdercoating.

 

That is a beautiful car! Nicely done!
Do not worry about blasting the frame thinking that it will make the final surface rougher...it will not. The PC will be smooth as glass unless it is applied overly thin. The "run-off" when powder coating (the point where the powder turns to a liquid), makes a smooth top-side finish. Also, any areas that do end up tight due to the thickness of the coat, just take a grinder with 60 grit pad to it...you will not need to do that very much if at all.

There are also several large holes in the frame that the PCer can insert the tip of the gun and spray powder. The inside of the frame will fill with PC and due to the electro-static nature of PC application, the powder will find its way all over the inside of the frame. If you then go back and soak the inside tubes with the paint of your choice using the garden sprayer method, you can be assured that you have sealed off every area...the frame will last another 50 years!