As I have already done with the front arches, it was the turn of the rear. First job was to remove the years of butyl underseal to see what I was dealing with. As with the front, there were a couple of small holes but on the whole they weren’t too bad, albeit the nearside spring mount needed replacing.
I made a couple of steel patches from 1mm sheet steel and bought a spring mount repair panel (far to complex to fabicate witha vice and a hammer). After welding them in place I covered the arches in RustBuster Fe-123, as I had done with the fronts, in the hope of subduing the rust sumewhat. As another nod towards greater longevity I also lined the edges of the inner wings with P40 where they meet the outer wings, effectively removing the lip that forever fills with mub, salt and debris. Finally I seam sealed and coated everything in Rust Buster epoxy mastic 121.