Corvette Frame Restoration - Discoveries Down Under

Removing portions of the endplate and framerail reveals the culprit: the internal gusset that creates a chamber within the boxed frame. Once dirt gets in here, it stays there and greatly accelerates rust damage.

A replacement piece of steel is cut and fitted to the underside of the framerail. This piece is then tack-welded in place.

Surface rust and rust scale are ground off near the cuts to enable a secure weld. The inner replacement piece will be welded from the inside because the inner cut is covered by a gusset.

After the rust is ground, the inside surfaces are brush painted with POR 15. The replacement steel for the other portion of the frame is cut, fitted, and installed overlapping the outer piece like the original.

The outer piece of framerail is now ready for final welding.

The weld is ground flush with the frame.

After the lower portion of the endplate is fitted and welded, the upper weld is also ground flush with the surface of the remaining original portion of the plate.

After grinding, any pits or deep grind marks can be filled prior to painting. Fortunately, the outer surface of this frame has no surface rust or pitting, so the replacement steel pieces look the same as the rest of the frame.

POR 15 is brushed over the bare steel and adjoining areas for rust prevention. It also serves as a primer for the topcoat, which is applied the next day.

A semi-gloss black topcoat is sprayed after the POR 15 is sanded. The repair is invisible, and the frame now looks good when viewed from underneath or through the wheelwell.

A body-off frame helps show the area where the body-on-frame repair will be done. A portion of the endplate of the framerail, and the area beneath and just in front of the endplate, will be removed and replaced. This area is the Achilles' heel of C2 and C3 frames.

The lower portion of this endplate is completely rusted through. It is not structurally important, but it is visible in the wheelwell at the front of the rear tire. Because a flap of fiberglass covers the upper portion, the plate is cut a little below the fiberglass using a die grinder.

The overlapping bottom pieces of the framerail in front of the plate are also rusted through. Tape is applied to help make the die grinder cuts straight. The framerail pieces are cut on the lower corners so that only flat pieces of steel are needed for the replacements.

The inner surface of the removed portion of the rail shows how localized frame rust can be. The steel is completely rusted through where dirt was accumulated, and yet the steel is perfect just an inch to the right.