Cruciform chassis, sills and rear spring hanger corrosion
SeriousBodywork & RustThe unitary bodyshell of the Sunbeam Alpine relies on a multi-layer box sill assembly and an underfloor cruciform member for torsional stiffness. Water entering through neglected windscreen scuttles, blocked A-pillar drains, and rotten rear inner arches collects inside the sills and rear spring hanger boxes. On UK cars exposed to road salt and damp storage, internal rusting weakens the shell to the point where the chassis folds upward in the middle, causing the doors to jam against the B-posts. Repairing this structural decay requires extensive jigging and skilled fabrication of bespoke steel sections.
Doors stick or rub against the rear wing apertures when opening and closing, Visible distortion or sagging of the rear suspension where spring hangers attach, Softness and bubbling along the outer sills, jacking points, and floor pans, Car flexes visibly when jacked up, preventing doors from shutting properly
- Inspect the cruciform chassis brace and inner sill boxes from underneath on a ramp
- Test door shut lines with the car on level ground and check for top-rear wing contact
- Attempt to jack the car at the rear jacking points and watch for metal deflection
- Run a magnet along the lower front wings, sill covers, and rear arch seams to spot filler