Hi folks, the front brake DIY is extremely straightforward and well-covered by previous members, but the rears on a 2016+ are a bit different. Just wanted to show you some quick pics and explain the basic process of dealing with this new design.
First thing's first, I had to order factory OEM brake pads from an online Mazda parts company. I could not find the correct part number when searching, and had to research the forum here for a part number. The hard part came when some folks describing the part number used "o" in place of "0", and so on. But I eventually nailed it down, here it is:
The factory original pads are made by TRW, and the replacement OEM pads continue this. Other members have researched this and know them to be OEM's for German brands that use electronic parking brakes.
You can see the plastic electronic parking brake device in this pic.
So first jack one side and set a jackstand under the rail. Then made sure the parking brake is OFF, and remove the wheel. Pop the hood and then undo the brake cap to take pressure of the system!
Use a T30 Torx to remove the plastic parking brake device, there's just two screws that holds this. Clearance is tight, I used a T30 bit on a ratchet first, but had to swap to an L Torx to clear the shock.
Unbolt the caliper, hammer off the stock rotor (with a rubber mallet), and if needed, clean off the rust scale on the mating surfaces with a metal brush and brake cleaner, and install your rotor. I went with a new Stoptech slotted rotor.
Pull the pads, you'll need to clean the glue off the piston and brake pad bracket. I used brake cleaner and a nylon bristle brush to get in there, worked well and its safe.
Now this part is very important! Take a T40 Torx and insert it in the back end of the brake caliper actuator. Turn it clockwise until it stops, which for me only took a few turns.
This resets the emergency brake part behind the regular brake piston. Then use a tool (or what I did, I used a woodworking clamp...don't judge...it worked) to carefully press back the piston. Go slow, and clean the piston's rubber seal as you go. I love using Tub-O-Towels solution-soaked towels in these situations.
Install the new brake pads and hardware, don't add grease to the backside of the pads, you'll prevent these suckers from sticking like they need to. Bolt up the caliper, screw on the e-brake motor, check your torque on all the bolts, get your wheel back on, and drop that side back down. If this is the last wheel you're doing, screw the brake cap back on and drop the hood.
Do the other side, and then when you're all done with both, re-engage the parking brake and listen to the motors whirl for a while until they cinch down. Then disengage and re-engage a few times, just to make a sure.
For me, this is all it took. I of course did my fronts first so right after this, I took the car out and tested my new brakes. EXTREMELY impressive difference from what I started with on my used ~24k mile new-to-me 2016.