Dan, my shop landlord and the gentleman helping me build my Sprite, or maybe I should say I am helping him, has a brother named Dick with whom we share shop space. Dick's car is a 1929 Ford Model A Tudor sedan. The car was a beautifully restored show car until it became trapped in a garage fire. The car did not actually burn but was significantly damaged by the extreme heat. It has set in the shop for a few years, partially disassembled, awaiting restoration. Maybe Dick saw the progress we are making on the Sprite or maybe not. Anyway, he decided to take on the restoration. Dan and I will be helping. Here we have the entire body and all its related bits loaded on my trailer to be taken to the media blaster before we start. That's Dan's MGB visible in the third photo.
Well we got it back from the blaster in just a couple of days. It looks like we should have told them to also remove all the filler material. All but the thinnest edges remain and the metal is rusting a little under most of it. We have been D/A sanding all the removable parts for a few days and still have more to do. So far the only significant rust we have found is at the bottom on the cowl. There are structural supports inside that made two panels close enough together to trap debris and moisture. We have panels ordered to replace them. We will see how they fit; internet reviews have not been entirely good so far. In the worst case, I will just patch in the rusty section. The left photo, upside down, shows the cowl as it was returned from the blaster except the rivets have already been removed from the flange on the top (bottom actually). The rust is obvious. The right photo gives a better view of the structural brace that probably caused the rust. The following photos show the brace after it was removed and a couple of views of the resulting rust.
We are using epoxy primer from Southern Polyurethanes. This was recommended by my favorite paint supplier, LM Auto Color, as a supplier who specializes in restoration work more that production body shops. It is late August and early September and we have been hit by 90 plus degrees every day. We need to get the metal in primer as soon as possible so I called the manufacturer this morning to ask about advised maximum temperature and humidity. The answer was "No maximum, 100 degrees and raining is fine." I think I'm liking this company a lot.
Oops, it looks like I just found more major rust. The first photo is of the floor board and platform for the rear seat. Notice the significant rust in the floor section. I understand a bottle of muriatic acid was spilled in that area and this is the result. The second photo shows the same panel from the bottom. Several rust-through pin holes are visible just below the large "dimple" in the center. This is much too thin to weld from the bottom and access from the top for patching would be very difficult. Since this area is under the seat and not visible, I think some PC-7 epoxy is the ideal fix to eliminate any possibility of water intrusion. The third photo shows what we have sanded and ready for primer now. When spread out, or hopefully hung up, that is probably enough to fill our makeshift spray booth so probably time for primer soon now.
Well, we finally got all the pieces except for the main body and doors sanded and ready for primer. This did include some metal straightening and some welding. So here they are, all 20 pieces. Some hanging and some laying. Hanging parts this way is not necessarily ideal but it does allow for access to all sides during one session. The down-side is they want to move when hit by the air from the paint gun and they have a tendency to spin and touch one-another. Also, getting to the lower parts of some pieces, like those huge front fenders, can be quite challenging. All things considered, I would still probably do it the same way next time.
Another thing to really like about Southern Polyurethanes epoxy primer is it allows for up to 7 days to apply top coating before you have to sand and recoat it. We decided to go ahead and paint the back side of all the black parts to avoid having to sand later. There is still some finish body work on their outsides so that could not be painted yet. Here they are, not quite perfect but they are shiny. The undersides of the fenders show a little pitting, from rust I assume, that we elected to leave. The other pieces are pretty good.
We finally got the body sanded and all the old filler removed. Like the aprons, every bit of filler on the body also had at least minor rust under it. Also where the top was covered in fabric, there was significant rust pitting in the metal. I actually primed it a few days ahead so I could fill the pits. I was afraid they might actually telegraph through the new fabric even though it will have a cotton padding under it. Now, after the epoxy sets a day or two, I will have to reapply all the filler I took off. But this time it will not rust underneath. The only stuff left now is the doors, the wheels and several trim pieces, which are all at the sand blaster now. These photos show another feature of this particular epoxy. It has enough low gloss to readily reveal many of those little flaws that try to hide until you get the final paint on.
I waited a couple of days then applied filler to the most obvious flaws. The large ones had filler remaining after returning from the sand blaster so I knew where they were. The others were not so obvious until the epoxy primer brought them out.
After sanding and feathering all the filler, there were enough spots of bare metal that we decided another protective coat or two of epoxy was in order. No photos here as it looked the same as the earlier set.
The next step was deciding on what primer/surfacer to use. I have used the urethane high-build primers with good results in the past, specifically PPG K200. These are still available but current technology today is polyester high-build primer. This stuff is essentially sprayable bondo and can be built to two or three times the build of urethane or maybe even more. It is the DIYer's savior. I had two concerns though. Being polyester, it uses MEKP as its hardener, in a ratio of 2% or so. That is a couple of ounces for a gallon. It seems that it would be really easy to get it wrong mixing smaller amounts. The other is the pot life. Like bondo, it kicks off really quick. In most cases you have to get it out of the gun in half an hour. That is from the time you mix it until you clean the gun.
My paint vendor convinced me I could handle it. After I assured him we had no bare metal, he recommended a product named Slick Sand by Evercoat, the company that owns the Bondo name, as the stuff most high-end restoration shops use. I have to agree that it is really nice stuff. The gallon comes with 4 tubes of hardener, one tube per quart. The tubes are also marked off in quarters so it is simple enough to mix 1/4 of a quart or 8 ounces at a time. We had the doors and hood (4 pieces) ready so I mixed 16 ounces and half a tube of hardener and started spraying. This was enough to give almost 3 wet coats to everything, with Dick keeping an eye on his watch so I didn't exceed the 30 minutes in the gun. It sanded easily with a long board and 220 grit paper. We got flat surfaces very quickly. In short, I am sold on polyester as the way to final prep for paint. I forgot to mention that the temperature of everything has to be above 70 degrees. That includes the air, the gun, the paint and the stuff you will be painting. If it drops below 68 then it will not harden. And it must be kept there until it has fully hardened, at least another two hours.
So today, instead of swapping parts for the next batch of Slick Sand, dick wanted to build an adapter to mate the engine to our engine stand. I forgot to mention that while I was painting, he and Dan removed the engine and gearbox from the chassis. The reason for the adapter is the Model A flywheel that extends a full 2 inches beyond the rear of the casting. Then the clutch goes another 2 beyond that. He scrounged up a piece of 3x6 inch by 3/8 thick angle 76 inches long. I'm not sure how he dragged it to the shop. We got the pieces cut and fit but ran out of time before welding. I'll post pictures of the finished product tomorrow. By then it is forecast to be too cold and wet for painting.
So here it is. Dick did the design and I did the welding. I'm not really a welder so I did it with some trepidation. We did leave it loosely attached to the hoist with some slack in the chain overnight just in case. As Dick said, "we trust the welding but we wouldn't sleep under it tonight." Well it held so I guess it is all right. The adapter is only attached to the engine at the motor mounts on both sides near the rear. The reason for mounting it from the front is so the gearbox can be mounted to it while still on the stand. That is the gearbox on the floor below and behind in the photo. It is cast iron too.