My Cobra Build Site

The last several weeks have been a blur of activity, all surrounding the body work adventure. When I first thought about doing my own paint and body work, I was pretty scared about it, hearing all of the 100’s of hours required to do it and how difficult it was. Now that I’m neck deep (literally) in the process, however, I’ve found that it’s not any worse than any other part of the build, and actually just as enjoyable.

The first thing to realize about body work is it makes an absolute MESS. If you use 2-3 pails of body filler, 80% of it will probably end up on the floor as sanding dust, which has the consistency of a light bread flour. Depending on what your work area is comprised of, it’s unlikely you’re going to want that stuff all over the place. If you happen to have a small one-car garage, and nothing else in it, you might be okay, but if you don’t, then you might consider building your “room inside a room” like I did. Basically, I built a two-stage room, a sanding booth, and a paint booth.

I thought I’d pass this along to other guys doing their own paint/body. I have a pretty large shop, about 1200 square feet, so the prospect of cleaning dust from the entire thing scared the crap out of me. I also plan to paint at home (we live in the boonies, so no EPA stuff,) so I wanted to build my own booth.

The first revision of this is a self-contained sanding booth, which after generating 1/4″ of dust over the entire floor of it is already proving well worth it. I’ll firm it up a bit more and add an air handler and real door before I start paint, but this is good for now.

To keep it simple, I just made it 10′ x 20′ x 9′ high. That means only about 6 cuts on the pvc pipes, the rest just stick together.

I used 4mil plastic, which is about $25 for 100′ at Lowes. That completely covered all 4 sides and the “roof” completely with some left over.

I sourced all parts at Lowes, with the exceptions of the 3-way corners, I had to buy those online. You can get them at Amazon, but they might be cheaper somewhere else. Amazon.com: 1-1/4″ 3-way Elbow PVC Fitting Connector: Everything Else
Like I said, I need to firm it up by adding some T’s and additional cross braces on the sides and top. I ended up duct taping some braces for the time being since I didn’t want to drive the 30 minutes back to lowes.

I used 1″ SCH40 PVC which is about $1/stick cheaper than 1 1/4″ schedule 80. Even at full 10′, it’s pretty stiff, but adding a cross brace at 5′ is better. You’ll have to do the math for yourself between more fittings and thicker PVC. The 1″ is also easier to store when it all comes down. The only thing I had to adjust for is that the 3-ways were 1 1/4″ so I did some bushings to reduce them down. You might be able to find actual 1″. I didn’t really do the math until I got to lowes.

I didn’t glue anything, it’s all just fit together, and the plastic attached with duct tape ever 4-5′. The duct tape works really well as it sticks instantly to the plastic.

Adjust your size as needed, I bought the pvc lenghts, T’s for the braces and mid points, and the 3-way corners, plus the plastic (which will be replaced before paint. I’m also adding a working hinged door, an air handler filter, and kraft paper on the floor, so I’ll update that later.

I also added and taped up the holes for my air hose, long shop vac hose, and the overhead extension cord. It’s not completely air tight at this point, but after about 30 hours worth of body work, it’s kept probably 98% of the dust out of the rest of the shop.

This all cost me about $125, so far, plus the other stuff that I need to buy later, another $40 or so.

Pics:

And the Real Work Begins:

Since Christmas, I’ve tried to spend as much of my free time out in the shop as possible, and I’ve managed to rack up 30 hours worth of body work time. I’m actually quite surprised at how far I’ve gotten in that amount of time.

I had already knocked down the seams before I drove around in gelcoat, but I still needed to go back and do the job right. I went all around the car, and used my angle grinder to cut down each seem to remove the gelcoat completely from each one, checking for any gelcoat in the actual seam. My car is a MK3.1, and it appears that the overall condition of the gelcoat bodies has improved to the point where the real hard work on the seams is largely unnecessary. I didn’t find more than just a couple of spots where the gelcoat was deep enough into the seam to require that much come out. In general, I ended up grinding down the seems and taking 3/16-1/4″ deep from the level of the rest of the body.

The nice thing about the seams not being in bad shape is that it meant that I could skip a step that was necessary on previous bodies: applying HSRF to each one before doing to filler. I was a little nervous about skipping it, but after all of the horror stories with sanding HSRF, I was glad that I didn’t have to deal with it.

So, the next step was to begin filling the seams with Rage Gold, the preferred filler of other builders. It’s nice stuff, mixes pretty easily and sands of very well. After reading other informative posts about doing body work, I used one of the tricks I found there, using a hacksaw blade to screed the body at the seams. The advantage is that you can pull the blade across the seam while bending it to the exact contour of the body. This makes for a surprisingly smooth sanding surface, rather than having to sand a very bumpy surface. I found that you can only really use this method on the tops of the fenders, but as this is a big part of the seams process, it’s a huge help.

It took 3 coats of filler to get the seams to a point where I was satisfied with them. I used my Dewalt palm sander (1/4 sheet size,) to do all of the sanding on the first two coats, which made it go pretty fast. I did the 3rd coat by hand, mostly with a small foam sanding pad. This coat left a few pin holes and low spots, so I’m currently working on touching up those areas. I’ve run out of Rage for now, so I have to wait for that to show up before continuing.

The other thing I’ve started on is getting the doors evened out with the body. I spent a few hours working on the door alignment, adjusting them to the point where they were in the “best fit” position. On both doors, the fitting at the cowl and at the bulkhead ends were the worst, and required a lot of building up. The end result is, of course, having the doors and the body line up perfectly all the way around. I’m on the first coat of filler on both doors.

One “tool” that really makes doing the filler easier is a “mixing pad.” It’s basically a clip board with a handle on the bottom, and a pad full of non-porous sheets (like wax paper) that tear off one at a time. You mix the filler a little at a time, then tear off to a clean sheet for the next set of filler. I found that even in my shop where it’s about 60 degrees or less, I could only do about a 4×4 inch by 1″ thick amount of filler before it started to set up. Once it sets up, you can’t spread it any more, it just doesn’t flow well enough.

I also found that you don’t have to be afraid of running out of hardener. I was worried about that as I mixed each batch, but when the can was empty, I still have quite a bit left over (probably 5+ batches worth.) I did make a mistake on one of my batches and didn’t get enough hardener. It’s not evident until you go to sand, at which point, the filler will ball up like crazy and gum up your sand paper. I was glad it wasn’t very much, I went through way too much paper, and it was a pain.

Another tool is a sand paper cleaning “stick.” You can get them on most wood working websites, and even amazon.

Once my filler gets here, I’ll finish up the doors. I ended up putting too much filler on the top of the doors, so I’ll blend that in and fare out both ends, plus all the way around. The driver’s door was far worse than the passenger, but both of them needed quite a bit of work.

While I wait, I need to sure up the body buck so it’s more solid for sanding. My next filler steps are to finish the doors, clean up the trunk lid lip, and then work on the rolled cockpit edges, as well as getting the door, hood, and trunk lid gaps perfect at 3/16″ using Greg M’s foam insulation trick.

I’m finding that most of the body work is just easier to do with the body on the chassis, since a lot of what needs to be done centers around the door, hood, and trunk alignment. All of those parts are tied into the chassis, so you really have no choice but to leave it on. The pro painters have enough experience to not need this, but most builders don’t, including myself. The downside is it makes an absolute mess of the chassis, so I’ll have hours and hours of clean up work to do.

More to come….

Pics:

One other thing I’m working on is getting the “bend” of the hood corrected. It’s too flat where it meets the cowl area. So, I’m taking a page out of Scott’s book and using a ratcheting tie down to bend it. If it were summer, I’d leave it out in the sun, but I’m using a small space heater instead, which is far slower, but so far it’s working quite well.