Fixing bad rust repairs

With the old etch primer and patches of primer/filler now removed from the Mini shell, a surprisingly large number of pin holes in the panels were exposed. All these pinholes were welded up, however I found much worse issues involving previous low quality rust repairs.

The curved panel section next to the rear wheel arch seam wasn't repaired well so the panel was cut away, only to find untreated rust underneath and had a panel just welded over it (as well as several small holes at the back).

This whole area including the seam was cut off, holes welded up and a new lower part of the seam remade. The inner area was then painted with (black) zinc paint.

A patch panel with an upper seam strip was then welded in.

A previous repair of the rear wheel arch rear lip (joining the boot floor) resulted in a weird overlap in the panels : 

After some cutting and rewelding this was fixed, then the large rust hole exposed by the recent sand blasting was also patched.

Everything fixed and all welds cleaned up :

The drivers side wheel arch had an (attempted) repair which was just a glob of messy welds which didn't even penetrate into the base metal. Grinding the welds back revealed a ~25mm rust hole between the cabin & wheel arch, which had to be properly repaired with an inner and outer repair piece welded in.

The passenger wheel arch had a couple of rust holes at the (very hard to reach) top corner of the wheel arch. I cut an access hole next to the door to investigate and found multiple rust holes large enough to stick a 12mm drill bit through.

This repair would involve removing the A-pillar inner & outer panels to get access to the upper wheel arch, and replace them with some new panels.

The outer A panel was first cut off 

The inner A panel was then removed which exposed a huge section of rust damage that had never been repaired properly - just a piece of steel welded over it. There is supposed to be a vertical panel here, not a gaping rusty hole.

The low quality repair at the bottom of the inner guard was also cut out.

After the couple of gussets in the upper wheel arch had the spot welds drilled out and removed, it revealed a massive rust hole that was hiding behind them.

The inner guard was cleaned up, rust in the upper guard area cut out and new steel sections welded in to repair all the rust damage.

Some 3D prints which matched the external hinge hole positions exactly were bolted to the door. These hinge prints allowed me to determine the exact position required by the A panels by aligning the holes in the prints with the holes in the new A-pillar panels.

The passenger door was first held in place using my 3D printed door hanging tool and gapped correctly using some panel gap tools.

A substantial amount of time was taken for tweaking & fettling the new A-panels to fit exactly, including panel beating the seams of the two panels to close the seam gap.

Before :

After :

The inside faces of the repair panels and upper wheel arch areas that will be inaccessible once the panels are fitted were painted with zinc paint to mitigate formation of rust.

...then fully welded on and the A-pillar seam was then welded back up. The gusset piece in the upper wheel arch was welded back in place at this time. 

A repair patch had also been welded in the drivers side front wheel arch and given the low quality of repairs I'd already found, I cut this patch off... and found yet another example of a steel piece just welded over the top of rust damage.

This was fixed after treating the rust behind the wheel arch with zinc paint. I welded in some new steel - correctly this time which includes the way the separate inner A-panel is supposed to wrap under the sill.

The last repair was to fix the (de-seamed) body curve profile at the base of the C-pillars. The panels had to be cut and panel beated slightly to correct the panel alignment.