Nearly every early 911 exhibits the same rust pattern in the front trunk area. The original twin batteries will leak acid, compromosing the battery boxes, the fuel tank support and finally, the front suspension pick up points. We knew that our fuel tank support needed some patching, but we weren't sure if the rust had extended all the way down into the suspension pan.
The good news is that while there was some rust in the suspension pan, it was deemed saveable and we patched a few sections after we cleaned it up with a wire brush on a grinding wheel. We then replaced the fuel tank support with one of our new reproduction pieces.
To weld the tank support in the car, we used an Eastwood MIG welder and a technique called a "rosette weld" which is a fancy name for welding a small plug in sheetmetal. We drilled a series of 1/4-inch holes around the perimeter of the support that were spaced about 1.5-inches apart. The rosette welds are then used to recreate the factory spot welds. With a quick touch-up of an angle grinder and sanding disc—the welds look just like the factory production line versions.
