Suggested indicators of this condition are:

• Minor rust staining in the rear of the base of crossbeam beam end closure plate.
• Seat belt mounting corrosion in the wheel well.
• Rear side window frame base leakage.

I recommend that prospective buyers check the areas above using a thin sharp probe.

The outside of an assembled and painted 2CV shell may look to be in perfect condition. However in my Dolly and the Charleston wreck, major structural corrosion was hiding inside the crossbeam end closure & C pillars. It may be that this condition is widespread as its cause seems to me a design shortfall.

The end plate design and execution, seems to me to be wanting. It is a structural item which transfers body loads to the C pillar significantly adding to body strength . Breakdown of the endplate to C pillar join results in movement and corrosion of the C pillar rear face and the end plate wrap. The poor fit of the C pillar to the rail, hidden by flexible body sealant, adds to the problem.

The original end closure is spot welded to the centerline of the rail, by a small number of welds. Water and junk collects in the sill & end closure gap, giving conditions necessary for corrosion acceleration. On my 1986 Dolly and a 1982 Charleston I wrecked, the rear end of this closure is bent around the inside of the C pillar and covered with the beam rear closure (see below). It both cases it may have originally been fixed to the C pillar by welds, however there was no sign of this on disassembly and the remnants of this end were not fixed.

LEFT Rubbing and corrosion of the C pillar rear due to the loose end closure plates, seen on 1986 Dolly & 1982 Charleston.                   RIGHT Another puzzle solved, removal of rear seat belt mounting plates (corroded) gives access for spot welder prongs

Repairs to the end closure using heavier 0.8 mm zinc plated steel made from templates of the old pieces, enabling the new pieces to be strongly Mig plug welded to the C pillar. The closure bottom of was lowered to "close" the structure & increase its strength and to allow spot welding to the rail. All gaps including the rail space side were later filled with POR Patch (semi liquid POR paint).

 

Typical gap between the C pillar & the rail. Originally this gap was filled with flexible body sealant, and there was evidence of corrosion underneath this material. The metal had been painted before sealant application (appears to be a general 2CV factory process to flat rolled steel before pressing of panels). Body sealant manufacturers recommend the surfaces of the metal to be sealed be bare, clean and wiped with Prepsol or equivalent immediately before application.

C pillar splicing repairs using a good piece from a wreck. The splice length was 25 mm., and the "tubular" part of the join brazed. The flange part was spot welded (surface preparation on these old parts needed avoid burn thru etc. due to rust)