S30 Z-car rust: the areas that decide a project

The S30 chassis is a unibody, and its rust problems are structural rather than cosmetic. Floor pans, the rocker panels and the frame rails beneath the doors carry load — corrosion there changes how the car drives and how safely it crashes.

Look under the carpet and under any vinyl or sound deadening. Check the battery tray area for acid damage and the rear hatch surround for trapped water. On 2+2 cars, inspect the longer roof and the rear quarter structure closely as well.

Check the front frame rails and the radiator support, then the rear suspension mounting points. These cars are often modified, so look for poorly executed repairs: overlapping patch panels, plates riveted over rust, or fresh seam sealer applied over bare metal.

Panel availability is reasonable but not universal, and good shells are worth paying for. If the structure is sound, almost everything else can be replaced.