Brothers Trucks 1947-1954 Cab Corner Patch Panel Installation

02/29/2016

Brothers Trucks 1947-1954 Cab Corner Patch Panel Installation

02/29/2016

The rust along the bottom of this cab corner looks like it might be repairable with a little flat stock, but looking inside you realize that rust has severely pitted the area below the broken line. If you try to weld to it, it just burns back making the work miserable and you may find the repair is temporary.

I can split the bottom and inside end at the factory spot welds, but the end by the door and top is sliced across the panel. If you take a stiff welding rod and lay it along the side like shown, you can get a decent cut-line marked over the curved panel. Mark it out and check that the cuts are in the right places before the first cut is made.

As you can see, the Brothers cab corner repair panel is much larger than the area that needs to be replaced. You’ll rarely use a full panel, but it’s nice to have more than you need instead of less. In any case, make sure the panel and the proposed cut-out are not at odds. This is one of the best panels for shape, fit, and material I’ve used.

Cut the bulk of the section with a cut-off wheel. The top and door-end cuts are finished cuts, but the bottom and inner ends have strips that are still held by spot welds on the factory seams. Don’t even try to take it out all at once – it’s wasted time.

The spot welds at the inner end were drilled out, leaving the original inner panel lap flange (A) in perfect shape but for a little surface rust, but the lower edge of the inner panel (B) was pin-holed with rust. The time to repair the inner panel with a patch is now!

Brothers offers an inner cab corner patch panel for this very application but since the rust was limited to a square inch section we decided to use a piece of sheet metal and fabricate the piece instead. I cut out the rusted area and clamped a small piece of sheet metal to the rear. Form the sheet metal to fit the contour of the opening. I use a sharp awl to scribe the edge of the opening on the new patch.

Carefully cut the patch out exactly on the lines and it will be very close to perfectly shaped and sized. The sharp point on the awl is essential for an accurate mark. With just minor trimming by grinding the edges, the patch falls into place without force and leaves a hairline gap around the perimeter. Clean the edges before welding, tack first, and watch the heat buildup to avoid warping.

After welding the patch in and grinding the welds smooth, only the bright metal tells you it has been patched.

The repair panel is rough-trimmed along the top. I laid the panel over the opening as close to where it should be as I could, then reached behind and scribed a line on the back of the panel. I left it purposely long, you’ll find that trying to get a perfect fit in one shot gets you into trouble.

Cut twice and still too long? No, I re-scribed the panel, trimmed it again, and then used an air grinder to carefully trim the edges until the panel fit perfectly. I found I needed to slightly re-shape the panel contour to match the opening perfectly. The top and front edges (arrows) are a hairline fit and the inner end and bottom are laying flat on the factory flanges. Note that just two spring clamps hold the panel, so no distortion is evident.

I clamped the edges, tweaked the panel sligthly so the top and front butted the seams were just right, and then tacked the panel in place. I needed to slightly adjust the butted seam as I tacked so the panels were flush. Align, tack, align.

The bottom edge was drilled (just through the new panel) with 1/4 inch holes spaced about 1 1/2″ apart and rosette welds (fill-welds) were made to duplicate the factory spot welds.

Spot welds? Sure! I drilled 1/4″ holes on the rear edge over the original flange as shown. The drill spots open the top and clean the flange at the same time. Don’t drill through!

I fill the spots, using a rosette weld and making sure the weld started on the inner flange then filled out the cover of the hole in the repair panel. I ground the welds flat. Details count! The inner edge had to be trimmed and the flange is not flat so it took a little weld and grind action to make it look stock.

The finished panel after the welding and grinding details are complete. Only minor hammer and dolly work are needed and it didn’t take long to do. It will require a little body filler to conceal the rough edges but not much.

This is the completed repair after a couple of coats of epoxy primer to create a great bond to the bare metal and coats of primer/surfacer to fill and build for final blocking and paint. As you can see, I also filled the fuel tank filler hole using the same scribe, cut, fit, and weld technique.

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