I'm preparing to patch in a short preformed metal patch panel at the front cab corner and cowl. From the various illustrations in the catalogs from vendors of these body patch pieces, I see where bent surfaces of the new patch piece get welded on to the existing intact sheet metal parts of the cab. What puzzels me is what is used to close the back side of this patch panel. I see that full-legnth rocker panels repacements have the necessary material to function as the back side of the corner. On my truck, the rocker panel (which doesn't seem to be a separate piece at all, but rather part of the cab floor) is rusted so that there is no material to close the back of the cab corner. I don't want to purchase rocker panels just so I can cut and use the forward-most four inches. I huess I will have to bend so sheetmetal to close the cab corner front, but before I do, I wanted to see if anyone has dealt with this issue in a way that I haven't considered.
jvmcc

 

The preferred way to install a patch panel is to 'Butt Weld" the panel to the existing sheet metal. The panel needs to be cut precisely to fit the area being cut out, the larger the gap, the harder it is to weld. The only time I would use the entire patch panel, is if the complete panel is damaged, there is nothing wrong with using only a portion of the patch.

The weld (MIG) when properly set up, will fill the gap, front and back, so that the backside looks nearly as good as the front. A lip or flange for setting the patch to is not usually required and unless it can be sealed from the back side, is not as good as a butt weld repair (imo).

I hope this helps.

 

I purchased new front floors, new rockers, and new front cab mounts for my 51 F1, and made my own flat patches for the cowl. When I started cutting out the old metal, carefully drilling out the spot welds and chiseling apart, I found out the metal it was welded to was rusted to nothing as well. I ended up buying extra sheet metal (16 gauge I think) and started cutting out what wasn't structurally sound and welding in new pieces, then welding in the new rockers and mounts and floor. It took a long time, but the cab is far stronger and sound than it's been in probably 25 years.