Quarter Panel repairs- cutting out the bad metal

I've been thinking/agonizing over this next step quite a while. I know some of metal is bad on the quarter, but it's mostly on a lot of curved surfaces like the wheel well arch and near the decorative vents. Curved sheet metal is harder to weld than flatter areas, and welds in the middle of broad swaths of metal are more likely to have distortion and warping issues than welds near panel edges. So, the amount of metal I cut out will have to be balanced against my admittedly beginner's welding skills.

When doing a job like this, you have a couple options: you can get a full replacement quarter panel, a reproduction of what Ford used to build the car 50 years ago, or you can get a "skin".

The quarter panel forms the trunk opening as well as the door opening and goes all the way up to to the roof line where it's leaded to the roof panel. That would be a lot of metal just thrown away to fix a hole in the wheel arch. And they're pretty expensive. But the edges are well-formed and it's the most accurate replacement part. Replacing this panel is a massive job, but requires less welding.

The skins are meant to just be used as patches, not full panel replacements. As such, they are much cheaper than a full quarter panel, but the edges of the skins are not well formed and not useful for actually installing on the car. This panel would be chopped up to fit and then butt-welded around most of its perimeter. If I were a better welder, I'd be using a skin and cutting a smaller piece out of the car.

After a long time thinking about this, I decided to cut out the majority of the quarter panel's vertical skin from door to tail and as high up to the body line as possible, and use a portion of a real quarter panel as replacement metal. This way I preserve as much factory metal as I can, and get to use good edges on the front, bottom, and rear for plug welding to the car. This will leave me, however, with a five-foot-long weld at the top of the panel that will have to be done so as not to cause a lot of distortion or need gallons of body filler to hide after the fact.

For replacement metal, I could buy a full quarter panel for a fastback, but as it happens the quarter panel for the coupe is basically the same piece up to the body line, but a lot cheaper. So I got full quarter panel for a '67 coupe and use it to create a sort of skin panel that has good edges that can fitted right on the car. I will trim off the coupe-specific metal at the top of the panel so I can fit it onto the remaining panel on the fastback.

New coupe quarter panel taking up space in the garage.

It has all the edges and details right, unlike a skin panel. 

The new quarter has an piece that ties the panel to the tail panel, but I'm keeping mine, so I cut this off the new part. Just a few spot welds hold it in place.

Cutting off the coupe-specific metal from the top of the quarter panel so it'll fit up on a fastback car.

Marking the first major cut. I made several to make sure I was cutting only what I wanted. 

Yeah, I just cut a huge hole in classic car. 

Here's the backside of the part I cut out. The rot is clearly visible here, and the entire wheel lip is toast, as well as the metal in front of the wheel well (at left in this pic). Cutting it out was the right move, but now I have to do something about it.

There's more to this part than just cut out the old and weld in the new. The next few posts will show a bunch of the 'other stuff' that's required along the way.