Replacing the Rusted Subframe on a 1970 ’Cuda

As HOT ROD readers most likely know, unibody cars don’t have frames in the conventional sense. There is no single support structure that more or less everything is bolted to. Rather, unibody framerails are really just like every other part of the body shell. They are formed and boxed pieces of sheetmetal. Typically, they are formed from thicker material than, say, a fender, for example. This is so the structure of the car can handle the higher loads it needs to. Yet, because framerails are basically just pieces of formed sheetmetal, they can be replaced the same way as any other panel on the car.

It’s common to think that the front framerails support the entire front of the car, suspension, engine, and all, from under the floor, but take a closer look. That would be a lot of leverage on a very short piece of frame. No, the unsung heroes of front end support are the inner fenders. They, along with a small brace that runs from the top of the shock tower back to the firewall, are the structures that carry the front end load back to the firewall and the rest of the body shell.

This is why it’s so important that the inner fenders are structurally sound, and that’s why there are so many spot welds around their perimeters.

Recently, Muscle Car Restorations, in Chippewa Falls, Wisconsin, needed to replace the front subframe, shock towers, and inner fenders on a customer’s ‘Cuda. Normally they would perform all of their work on a frame table so support braces are utilized to hold the rest of the car’s body in a fixed place. In this case, however, the majority of the frame’s rust damage was to the subframe. The inner fender was not in terrible condition, but with the frame coming out, the best approach was to replace it rather than attempt any repairs.

See all 18 photos

See all 18 photos

See all 18 photos

See all 18 photos

See all 18 photos

See all 18 photos

See all 18 photos

See all 18 photos

See all 18 photos

See all 18 photos

See all 18 photos

See all 18 photos

See all 18 photos

See all 18 photos

See all 18 photos

See all 18 photos

See all 18 photos

Source: Read Full Article