My guide to determining whether a classic car's frame is structurally sound before committing to a restoration, because the answer to this question determines whether the project is worthwhile.

The inspection: get the car on a lift and inspect every section of the frame rails from front to back. Look for rust scale — the orange powder that indicates active rust rather than surface oxidation. Probe suspicious areas with a pick. Sound metal resists the pick; rusted-through metal does not.

Pay specific attention to the areas that trap moisture: the rear frame section above the differential, the sections inside the body mounts, the front frame section behind the bumper. These areas rust from the inside and look solid from the outside until they're not.

A frame that requires more than patch repair in structural sections needs replacement. A replacement frame is a significant expense but it's a foundation. Build on compromised metal and everything built on it is compromised.