The underfender areas were ugly.  I know that looks rusty, but its not.  Lots of old undercoating with plenty of embedded dirt.  I had at it with a wizz wheel, except used a wire brush attachment.  Just to get the heavy dirt and some of the undercoating off.

This is the only rusted area.  I ended up hitting this with actual cutting wheel to grind out most of the rust.

Here is the area after I hit it with wire wheel.  Vacuum off then, wipe it down with some brake cleaner.  Not much, as the undercoat “melts” with the brake cleaner.  Just enough to get the remaining dirt off, and present a fresh surface for new undercoat to bind to.

Her is that rusted area after some cutting wheel action.  Ready for a couple coats of POR15.

After I wiped down with brake cleaner.

Initial coat of POR15, added two more coats after this one.

All masked off for painting.  And taped up all the holes!!

Of course, mind you, all of this times two, as I did the other side at the same time.

Then a few coats of under coating.

The run marks are actually the old undercoating.  You can make out a lot of texture from what was left before.  Hey, its worked for the last 34 years, I’m not taking it off now.