Thread: frame prep

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ok, the Pete and Jake's chassis has been sitting here waiting for me to attack it. I have been researching the frame prep for primer and paint for quite some time now. I built a jig utilizing two engine stands as a rotisserie. I couldn't find any stands that didn't have a slight backwards tilt angle I hope it works!

I would appreciate any insight/opinions on the following:

The frame has minor flash rust. I was going to get it bead blasted but I might tackle it on my own with an air d/a sander. When the frame was delivered I liberally sprayed it down with wd-40 to protect it temporarily. Do I use a wax and grease remover to remove the contaminants? I was going to use a right angled mini air grinder with a d/a disc. I am concerned with what grit to use as I don't want to be too aggressive and have scratches appear through the primer. The welds are so nice on this frame that I am concerned about unnecessarily sanding the fillet off of them. I have read that a buildable primer is the way to go. Henry used a gloss black, correct? Is PPG DPLF 40 black epoxy primer (in event of rocks/road debris chips going through the color coat) the way to go? Is there a time frame whereby the frame needs to be painted after it is epoxied? What would be the final color coat? A single stage?

I know I threw a lot of questions out there. Hoping anyone can share their experiences.

Thank you!

I use an 80 grit disc on the DA, then go over it a second time with 180. Use a regular 6" DA on the bigger areas and a 3" on the smaller places, a sanding block where the DA won't reach. Angle grinders spin too fast, wear out the sanding discs almost instantly, and leave swirl marks on the metal. With the WD40 on it I'd suggest scrubbing it thoroughly with lacquer thinner, then a good wax and grease remover. DP 40 is a good primer, you should shoot paint over it within 24 hours, if not wet sand the primer with 400 before you shoot it with paint. I use a base coat/clear coat on a frame, just a bit more protection from chips.

Have you had the car all mocked up yet to be sure you don't have to do any changing to the frame? I like to completely assemble the chassis with all the fuel and brake lines installed and clamped along with any holes drilled necessary to secure electrical wires. Also a good idea to have all the exhaust cut, fit, and installed once to ensure you have all the necessary mounting points on the frame.

JMO, but I think a black frame is boring. Also with too much black paint on the frame and other components things start to lose definition. I prefer a contrasting color on the frame, or the same color as the body.

Dave, thank you for your reply. I am rethinking my idea of sanding the frame. Unfortunately I do not have a garage (home) to work at my leisure. I am leaning toward media blasting the frame. I have to find someone on Long Island that does this. Also, with the small window of time I have to epoxy the bare frame I might be better off.

That's a good plan too!!! If you consider the time element, media blasting isn't really all that expensive. Got a shop about 5 blocks from me that does blasting and powder coating---seems to do good work and not too bad on prices, I'll probably give him a shot on one of my projects.

Great thread! Thanks for the tips.

It's tempting to get too hasty on that beautiful frame prep job! Looks so good when it's done! But it's also frustrating when you decide to add a little bracket here, or change something for that widget that doesn't quite fit where you really want it. Now what . . . spray bomb? For best results, just do an easy de-rust, spray primer, build the car, then strip it down for a final nice paint job. Sounds like more work but you'll be much more satisfied with the finished product, and it'll actually save you time in the long run.
Roy (SAC Hot Rod)

I'll add in on the engine stands for a mini-rotisserie. The 5 degree upward tilt works OK, but you will get some wheel lift and instability at some positions as you rotate, so be ready to move through those positions quickly. I never felt that the frame was going to hit the floor, but it gets a bit dicey as you go through frame vertical. If I do another one I will get a second stand of my own (as opposed to borrowing one) and will cut & re-weld the top pipes level to eliminate the dancing.

I sprayed my bare frame down with WD40, too, and I agree with Dave 100% - before you start sanding get the WD40 off or you will push the silicone down into the metal surface with the sanding. Any hint of silicone will create fisheyes in your primer & paint.

I used single stage for a couple of coats, then on the final coat mixed single stage & clear 50/50 - my paint guy calls it "sugar coat" and says it gives the benefits of clear without the difficulty. It laid down like single stage, but glossed up really nice. I will use the same finish on the body.

I also agree on the full assembly comment. Nothing worse than getting that paint done, wet sanded & polished out only to find that you need another bracket welded somewhere.