OK. Whatever tab was supposed to be welded on the frame to engage the brake caliper bracket was missing.
Here's how I fixed it:
7/16 bolt, very strong.
Bolt becomes stud.
Drill 7/16 hole in the hanger where the welded tab was supposed to be. Not sure what kind of Chinese metal they used but it took a minute to drill a 1/4" starter hole with a very good drill bit.
Lock nut.
Now the brakes work like they are supposed to work and the caliper doesn't spin around and clank into the frame.
Oh, and changed the tire, too.