Brothers Trucks 1955-1959 Cab Corner Patch Panel Installation

03/01/2016

Brothers Trucks 1955-1959 Cab Corner Patch Panel Installation

03/01/2016

Since the sheet metal surgery was going to be so extensive on this project, we thoroughly braced the cab after properly fitting the doors and adjusting the gaps. This type of bracing probably isn’t necessary if you’re just replacing cab corners, but it is important to align the doors before fitting the patch panels. For home builders, we also suggest making alignment adjustments with the cab securely mounted on the frame to avoid excess fiex.

We marked a line on the cab at the top of the patch panel so he knows the maximum amount of material he can remove. He started cutting well below that line, getting rid of the damaged metal and gaining access to the inside of the panel.

You never know what you’ll find in a cab corner – dirt, debris, and even a pair of pedal pads! Here you can see that there’s rust on the inside, too. We eventually opted to eliminate the inner panel entirely(more on that in a minute).

We initially clamped the patch panel in place (overlapping the old metal) and aligned the front edge with the door. This will be one of his primary reference points. Look close and you’ll see that the rear of the patch panel is a little long. To fix this, we made a vertical relief cut along the edge of the “fin” and removed a little metal.

We’re jumping ahead a little here to show the fit of the panel in the door jamb area after it was tack welded in place. (We should also note that we’ve jumped to the other side of the cab in this photo.) Notice the top hole on the front flange of the panel that was used to secure it to the jamb. Like the original panel, the replacement overlaps existing metal along the edge of the jamb. Note too that the rocker panels/steps are mocked in place to provide another alignment aid for the cab corners.

In this photo, you can see the vertical relief cut (arrow) of the fin that allowed us to remove some metal and match the patch to the contours of the cab. (The cut was made with a band saw and the metal removed with snips.) The small tack welds are spaced about an inch apart all along the seam. Also note that we trimmed a couple of inches off the patch (the line showing its original height is still there) and made a smooth final cut on the cab to create a tight, even, and straight butt weld joint.

After achieving a proper fit and getting the panels tacked in place, we began final welding. Even with a TIG welder in his experienced hands, he still welds short sections and alternates welding from one area of the panel to another to minimize heat buildup. With a MIG, we suggest making another series of tack welds in-between the first tacks, then adding more tack welds between those. You’ll need to grind the welds as you go, but eventually, you can complete the seam with tack welds.

A straightedge is used to check the seam prior to final welding and at regular intervals during the welding process. Welding (actually, the cooling process following welding) will typically cause the metal to shrink and create low spots, which we corrected as he goes using a hammer and dolly.

A peek underneath the finished cab corner shows that the inner panel has been replaced with a simple strap brace and a fabricated patch to extend the floor to the rear wall of the cab. The inner panel could have been fixed and replaced following the repair, but it seemed simpler to leave it off. After all, the well it created was the original cause of the rust. Another modification worth noting is the reinforcement that we made for the rocker panels – just a simple piece of steel tubing welded in place that runs the length of the cab(arrow).

We saved the best for last – the finished shot of the completed cab corner. Can you tell me where the repair is? We didn’t think so. After final welding, we carefully ground down the seam, graduating to finer abrasives until the affected area was completely smooth. No need for filler here! The seam between the cab corner and the rocker panel has also been welded and smoothed for appearance’s sake.

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