Brake Upgrade - 1.8L Bigger Brakes

January 2012 - I decided that a brake upgrade was the next item on my to-do list. Well, the grinding sounds from my rear brakes were the real deciding factor. Rather than replace the pads/rotors with 1991 spec parts, I decided to upgrade my brakes to the later 1994-97 1.8L larger brakes. The only difference is that the brackets are different (and of course the pads and rotors) and I was able to source a set of brackets on Craigslist for a reasonable price and it included the rotors, pads and calipers as well. I was told when I bought the car that it had three stainless steel brake lines and one oem rubber line, so I decided to get the Stage 1 kit from 949 Racing - Carbotech XP8 and XP 10 pads, 4 new rotors, stainless steel lines, and Motul Fluid.
The installation was straightforward except that the hub mounted dust shield/backing plate had to be trimmed to clear the larger rotor. The front had been done before, so I did the back.

I was pleasantly surprised to find out that my car had all 4 Goodrige stainless steel lines and I was able to return my new 949 Racing lines without a hassle.

The Brakes looked great and I took the car out for a test drive to bed my new pads...

and when I returned I was shocked to see this on the left rear rotor:

After some research and some measurements and also a call to Flyin' Miata I came to the conclusion that my caliper was bent. Given the severe damage to the piston face and the measurement of "the fingers" of the caliper that contact the outboard pad, I think that someone tried to force the piston in when doing a pad change and used the "fingers" for leverage. The miata has an adjustment screw in the bck of the caliper and that must be used to retract the piston when changing pads/rotors.

The distance from the finger edge to the piston face was greater than from the piston face to the finger near the bridge over the rotor. Luckily, the used brackets I purchased included calipers so I swapped that one out and the problem seems to be solved.