Over the last few days I've made a big step in the right direction with this project. The car has been blasted, epoxy primed, and the underbody painted. I thought I would relate my experiences with this process since I haven't ever had this done with a car before.
Let me start by saying that although I didn't set the car up on a rotisserie for this, it would have been a much easier process all the way around if I had. The rotisserie has some advantages that I had not previously considered. I didn't want to go that route because I was worried about bending the car; with the inner rocker panels complete shot, I felt that the only thing keeping it straight was the side bars that had been welded onto the factory roll bar. With no hardtop to add additional support, I was worried that putting the car on a rotisserie would have led to it bending or warping out of shape. So, despite the fact that one of my friends had one he could lend me, I didn't use a rotisserie. Hindsight being 20/20, I should have put the car on a rotisserie as soon as I had the new inner rocker panels welded in solidly. Between the inner rockers and the side bars, I think the car would have stayed straight.
On Monday this week I contracted with a local guy to do dustless blasting on the shell of the car, plus the doors and some other parts. Dustless blasting is where they use ground up glass, finer than sand, which is sprayed along with water to take off the paint and rust. According to the guy who did the blasting, they put some kind of rust inhibitor in the water they use, to keep the freshly blasted car from rusting for the next 24-72 hours. Sunday, in preparation for the blasting job, I rolled the car on jacks out into the driveway, and put it up as high as I could on jackstands. I also put some plastic down under the car to catch as much of the sand as possible. Here's a picture of the car out in the driveway:
On Monday when the guy showed up I found out one reason why the rotisserie would have been a better option. The nozzle on his dustless blasting setup was at least a foot and a half long, and was rigid, with a 1-1/2" diameter hose attached. No way he was going to be able to get under the car, point it straight up in the air, and get to all the nooks and crannies on the underbody of the car. There was a lot of "I'll do the best I can underneath" from the guy, which didn't make me happy, but it had taken me a month to schedule the appointment with him and I didn't have time to re-schedule it, so we went ahead anyway. Later, I ended up hand sanding and wire wheeling the areas under the car that he couldn't get to. Of course with the rotisserie we could have flipped the car over and gotten the whole underside with no problem.
To do the shell and the other parts it was about a five hour process. After blasting everything, checking for spots that were missed, and blasting again, he rinsed the whole car using my garden hose, and mixing in some of that anti-rust stuff with one of those bottles that screws onto the end of the hose, kind of like what you'd use for fertilizer on your lawn. The sand, of course, gets everywhere, and it took over an hour to rinse the sand off the car. And of course, we couldn't get it all. I worked with the rinsing hose for a while, and you just couldn't chase it all down. Finally we called it quits on the rinsing and blew off as much of the water as we could with an air hose. Here's a picture of the car when this process was mostly complete:
We also tried the dustless blasting process out on a couple of the fiberglass pieces on the car, but that didn't work so well. It looked like the gelcoat on the fiberglass parts was being eaten away by the abrasive, even if he kept the nozzle pretty far away from the part. The guy said he had done dozens of Corvettes with no issues, but the Shelby parts must have a thinner or different gelcoat than a Corvette, because I just didn't like the looks of the areas where he had blasted. He thought the same thing, so we stopped after a couple spots on the trunk and one of the front fascia pieces.
After we got all done he was nice enough to help me push the car back into the garage, where I spent more time blowing off the water and more sand. I had erected a sheet of plastic around the car to keep the sand out of the rest of the shop, as well as the paint; I was planning to epoxy prime the whole car on Tuesday, and paint the underbody on Wednesday.
Later on Monday night I was out cleaning up the car some more, and around the spots where I had welded, I saw some faint traces of rust forming. So much for no rust for the first 24-72 hours...
Tuesday morning I took all the separate pieces and the doors, cleaned all the sand off them with compressed air and a vacuum, and put them in my paint booth. It took me about an hour for each door to get them completely free of sand, turning them over and over, continually blowing them out and vacuuming any sand that I found. There didn't appear to be any rust forming on the doors or the other parts so I shot them all with two coats of epoxy primer by noon. For years I have used a PPG product called DP40 as the epoxy primer, but I found out recently that it has been discontinued thanks to new EPA regulations
Reading online about the PPG replacement, I did not see a lot of good things. I ended up going with an epoxy primer sold by Eastwood, which a friend of mine had used recently with success. I also sprayed it with a new paint gun from Devillbiss, using something called their Dekups system. This is basically a collapsible, gravity feed cup for the spray gun, and has the big advantage of allowing you to spray with the gun at any angle. No vents to leak, and the cup kind of collapses around the paint as the paint is used up, making for a supply of paint to the gun no matter what angle you spray at. Later on Tuesday when I sprayed the car, this system was invaluable; I really, really like it. The Eastwood epoxy primer, on the other hand, gets medium marks from me. It did not result in a particularly smooth finish on the parts in the booth, although it did spray on OK. Now that its been a couple days I've been able to check the adhesion, and it seems to be good, although the blasted surface is an excellent surface for a primer and I would think nearly any paint would stick well on it.
Tuesday afternoon I started on the body. I spent 7 hours in total cleaning and prepping the body of the car. I must have vacuumed sand out of the interior a half dozen times. There were places that I could not get the sand all the way out of, for example the cowl area under the vents. I'd blow compressed air in from the top and the sides, in both directions, and no matter how many times I did it, when I blew the air in, more sand would come out. I finally got it to a minimum after working that area for about 45 minutes, but it was clear that I'd never get it all out of there. Under the car some of the sand was sticking to the sheet metal, so I scrubbed the whole underside with a Scotchbrite pad. Up in the middle of the transmission tunnel, and between the frame rails and trunk drop downs in the rear, the blasting didn't reach, so I went in there with a wire brush and tried to clean those areas up as best as I could. Obviously they didn't look as good as the blasted areas but I figured at least the epoxy primer would stick. Finally at about 7:00 PM I took some Metal-Prep, which I believe is phosphoric acid, and hit all the weld spots that looked like they were starting to rust. There were a few more of them by this time, but it wasn't too bad. I rinsed and dried after the Metal-Prep (actually I used PPG DX-579), and was ready to epoxy prime the shell.
I had purchased one gallon each of the epoxy primer and activator, and it is mixed 1:1 so I had two gallons of sprayable material. I had used about 25% of that on the parts in the booth, and I figured I had enough for the shell left over. Wrong, I got one complete coat on the car, then about half the car with the second coat before I ran out. All those nooks and crannies in the vehicle took a lot of paint. And, of course, when I was painting around the cowl vents a little sand blew up and landed on the cowl
I will have to sand that area off and try to reprime it, then have another go at getting more sand out of there. The painting took a long time; I was painting until 11:00 PM on Tuesday. Again, that gun with the Dekups system was invaluable under the car, under the lips of the trunk, up under the dash, etc. I don't know how I would have covered all those areas without it. Of course, if the car had been on a rotisserie, it would have been no problem with a regular gun.
The epoxy primer can be recoated up to 4-5 days without scuffing, so on Wednesday I painted the underbody of the car. I used Eastwood's Chassis Black, which I have used before with success out of a spray can. This time I had purchased it in quarts for use in the gun. You mix the paint 4:1 with the activator. I found I needed to thin it with their recommend urethane reducer by 10%-15% to get it to spray out of the gun reasonably well; as mixed it is pretty thick. I got two coats on the complete underside of the car and the outside of the inner fenders, using about 3/4 gallon of mixed sprayable material. The paint went on very nicely and it looks good. Here's a couple pictures of the car with the epoxy primer and paint on it:
So, now I'm back to more sheet metal work. I have to weld in the seat support in the interior, then the pans that go underneath the seat support on convertibles, and then start on the quarter panels. The blasting also blew a few holes open in the sheet metal that I didn't know about before, so I will have to patch those. Also, there is some rust repair to do on the doors. I'm sure all this will take me a few months before I can start the actual body work, but when this is all finished, for the first time since I've owned it the car will be completely solid. I'm sure looking forward to that!