Quarter Panel

The last of the ugly

The last major sheet metal repair is to replace the right rear quarter panel. This car, although relatively rust free, had a lot of damage. It had been hit in both quarters, most severely on the drivers side which required a new quarter panel and a new rocker panel. The right side was not quite as bad although it was hit hard enough that the trunk filler panel needed replacing as well. I purchased partial quarter panels for both sides but in retrospect, that was a mistake. Next time I will use full quarters because they would be much easier to install than a partial due to the amount of welding and metal finishing involved. I'll try to document this project from start to finish to serve as a guide for anyone who has contemplated replacing a quarter panel themselves but doesn't know how to go about it.

This is the quarter panel in question. I've already removed the rear bumper to gain access to the spot welds attaching the quarter panel to the trunk filler panel.

 

The original quarter panel is in good condition at the body line and above so I opted to make the cut line just below the body line. It's always better to use as much of the original sheet metal as possible because the reproduction stuff is never as good. I used a cut-off wheel to remove most of the original panel that will be replaced to give better access to the spot welds.

 I use an old drill bit sharpened as a sheet metal drill to drill out the spot welds, using care to only drill through the first layer of sheet metal. Going through both layers just creates additional work when it comes time to weld.

Since I'm not crazy about standing on my head to drill out the welds in the fender lip, an air chisel gets the job done nicely. Just try not to damage the lip on the inner wheel well any more than necessary to get them apart. Again, that just makes more work later on.

 

This is the trial fit for the trunk filler panel. I'll add a couple of Cleco's to hold it in place until the quarter panel is fitted just to make sure that it's in the correct position. It's a lot easier to move a Cleco or two if things don't fit well than a bunch of welds.

 

 I cut the quarter panel one inch below the body line with a sharp pair of aviation snips using a strip of masking tape as a guide. The panel was then positioned making sure it was sitting tight on the rocker panel and flush front and rear. Make sure that the bottom of the panel is aligned with the trunk filler panel as well.

A sharp scribe was used to mark the cut line on the existing quarter panel.

Carefully trim the panel to the scribe line. A nice tight fit means less headaches when it comes time to weld. It helps to make a rough cut a quarter inch or so from the line before making a final finish cut to the line. A sharp pair of Wiss aviation snips is a necessity for this job.

 

 A die grinder and wheel was used to cut the door jam area being careful not to cut through the doubler underneath.

Cleco's can be used on the joint to help align the panels. If the hole is drilled more on one panel than the other, they grip better.


Large corner radii are one of the problems with repro sheet metal. Since the radii on the front of the quarter panel are so visible, I decided to tighten them up. A couple of aluminum blocks with the appropriate radius and angle, held in place with a c-clamp did the job. A blow with a brass hammer made the front edge of the panel as good as OEM.

Another shortcoming of this particular repro panel was that the flange to connect it to the trunk filler was somehow left off. The original one was in poor shape so I had to fabricate a new one. I just bent some sheet over a piece of round stock to get an angle with the proper radius and then shaped it to fit by shrinking and stretching the legs. It's not apparent in the photograph but the parts is kind of "S" shaped to make room for the valence to attach at the bottom.

 I finished welding the trunk filler in place and after double and triple checking the fit of the quarter, decide to start welding it in place. I went along the edges of the joint with a grinding disc to remove the paint and e-coat to make it easier to weld. The most difficult welds are those attaching the front lower flange to the rocker panel. I punched six 1/4" holes along the flange and put a Cleco in the front and rear to hold it in alignment with the rocker panel. I'm not sure how those welds were done in the factory, but I found that they could be reached from inside the car. There was just enough room to reach in with the MIG torch and do those six welds. 

 Next came the hundreds (thousands?) of tack welds to complete the six foot long butt weld. The welder was adjusted so a one second pulse would fuse the panels together with a little extra filler as possible. This minimizes the amount of heat dumped into the panel and reduces the amount of metal finishing required. I started by tacking both ends and then started dividing the distance keeping the tack welds equally spaced. As the welds begin to converge, they will need to be ground down nearly flush with the surrounding metal. The best technique I've found for this is to use a grinder with a thin cut-off wheel. Hold the grinder at a 90 degree angle to the weld and use the edge of the wheel to grind the weld flush. A sanding disk or flat wheel at this point will create too much heat and distort the panel. Save it for the final finish work when most of the extra weld filler has been removed.

 The plug welds in the flange of the wheel well were done with 1/4" holes in the lip, clamped to the inner wheel well and mig welded. With the proper settings, no metal finishing should be required and they should look like factory spot welds (I got lucky on a few).

 After the welding was finished, the panel was pretty straight. There were a couple of high spots that I worked down with a shrinking disc. This was about the only option in some areas because there wasn't enough room for a hammer and dolly. The shrinking disc did a good job although it was quite a slow process.