[D13]

Is that a 3-D (heim type) joint on the front of the wishbone? Otherwise I would think it would bind.

On the wishbone, the axle mounts run crosscar parallel. As long as the axle is level crosscar this is fine, and it will rotate in the up/down plane around the front joint. There is enough compliance in the lower arm bushings to allow this.
Now, what happens on a corner when the axle tries to move side-to side? The triangle wont let it because all of the bushings have very little compliance side-to-side, right? So the whole wishbone will load to one side, and will have a rotational load looking down on the front joint. The lower links will also allow only a little compliance, with a push/pull that wants to rotate the axle back into position. So although there is a large load on the front of the wishbone it's probably not going to bind badly.
Now let's hit a pothole. The axle wants to roll side-to-side (one wheel up and one down). But the wishbone connection at the axle is U/D only, so the rear end and wishbone pivot around the front bushing of the wishbone. If this is not 3-D then it's going to turn the threads on the link and that doesn't bode well.
And now hit a pothole on a corner and the twist load at the front becomes... big.

Just trying to understand what's going on.

Oh, as for clearing metal, if it's not out in UV, try POR-15 clear! Tough, flexible, but will yellow in UV. Painted the rusted/ground gas tank in my garage with it 2 years ago and it looks just like the day I did it. But it doesn't see the sun.