The way the load of the battery is transmitted through the bulkhead puts stress into parts of thin metal that can’t really handle it.
At some point in the past someone had applied some repair panels to the bulkhead round the lower mounting points. These were untreated steel that had been liberally pop-rivited and had inevitably picked up surface rust.
Given the number of rivets, removing the panels isn’t really practical so the next best option is to clean them up and paint them.
Usual techniques apply here: remove as much of the surface rust as practical, treat with rust remedy, mask up, etch prime, prime and top coat.
This is another case where Citroen’s legendary build quality shows up. I’ve painted the patch panels with the correct Blue Nuit paint used on the body but this section of the bulkhead got little more than a cursory blow over at the factory – certainly not enough to cover the undercoat!
Also visible here is one of the cracks that had formed on the lower edges of the battery box. I’ve drilled these out to stop them spreading any further and treated them with Waxoyl to keep the tin worm at bay.
The old battery tray, even though galvanised and painted, was accumulating surface rust and, at the near-side top corner, was already eaten away. Whilst this wasn’t a structural issue it’s never good to have large areas of live rust in a car so I replaced it with a stainless tray.
The bulkhead mounting was in good condition and the bolts had been copper slipped so there were no issues with removal.
There have been two pop-riveted patches added to the lower mounting points and these had acquired some surface rust. Whilst I can’t replace the bulkhead or realistically remove the patches, treating them with ACF-50 (curtsey of the fine folks at TomB engineering) and removing the bigger rust source of the battery tray should stop things getting worse.
After cleaning up a few burs left over from manufacturing, the new tray fits in as the reverse of the removal of the old one. It secures using 8mm bolts and the two dim-dip relays fit on the off-side mountings. The battery negative earth also fits on the top off-side mount. (It’s the yellow wire in the picutre which was taken shortly before I realised I had missed it off and re-fitted it.)
The replacement yoke retainer rods came with basic nuts and a couple of washers but the old nuts had a flange that acted as a load surface against the springs so I kept those and used the washers on the yoke end of the spring.