What are they? Are they needed?

 

Looking at the parts catalog, the only thing securing the caliper to the spindle are the bolts and lock washers.

 

Are you talking about the washer/shim type clips? I think they are to prevent the aluminum calipers from reacting with the cast iron knuckle since they are dissimilar metals.

 

This was my thought as well considering the aluminum to iron interface. This car won't ever see winter so I think I am going to forgo the use of the clips since they are kind of dirty/corroded and I can't seem to find new ones readily available.

 

I'd still be somewhat scared about galvanic corrosion. I don't know what it's like in ortonville but here, the rain tends to be slightly acidic.

 

I think I know what you are talking about.
The little clips that slide over the bolt holes of the caliper...sometimes a pain in the *** and you got to bend them and whatnot to allow the bolt to go through to the Spindle.
Frankly they are so thin that it wouldn't matter if you ran them or not,and if you are worried about corrosion just hit it with a touch of Anti-Seize.

 

or you could paint both sides. i try to use the clips, but i think they are an anti corrosion thing too, Mazda did stuff like that all over the car.

if you can buy the clips, they are Mazda part number FB01-26-137

 

Use a bit of anti seize on the caliper where it contacts the hub. Even a bit of grease would probably do the trick.

 

^ I'd kinda to the same. But I'd use the clips and put anti-seize on both sides of them.