I have an 09 6s with the driver rear caliper sticking. Some background on the issue, I've replaced the caliper for the third time and finally realized that there's something else wrong with it. So I thought the brake hose had collapsed and was pinched. I just replaced the rotor, brakes, caliper and brake hose and the caliper is still sticking. It doesn't smoke or get overly hot but it's just sticking enough that the wheels not fully free and the brakes wear down in a quarter of the lifetime they normally would. For example the last time I replaced that side was in December 2015 and I just did them today. My suspicion is the e brake being stuck but I have no clue because it doesn't appear it's causing it. Any ideas?

 

I just got my '09 6s, so this might help me at some other time. I haven't had a chance to tear apart wheels yet to do brakes. However, gunky slide pins will hinder free movement of caliper. Every brake replacement I've done on my cars includes cleaning off slide pins. If they're really gunky and tight, I may take off caliper bracket and spray the slide pin holes with brake cleaner and take a rag and stuff if into the holes to wipe out any dry grease and spray slide pins and clean them well. Then apply fresh high temp greaese, or my favorite is synthetic grease. Worn out hardware on the caliper bracket could also cause some funny stuff as well.

As far as ebrake, I'm not very familiar with Mazda's ebrake system, but it can't be any different than my other cars with four wheel disc brakes. The ebrake shoe sits inside the rear rotor of my Chevy Tahoe which is sort of like a drum set up on the back side of the center or thickest rotor area that slides onto hub, and calipers and brake pads have nothing to do with ebrake. The ebrake shoe is round and sits inside the rear of the rotor; when you pull on ebrake, the almost completely round shoe is spread apart and makes contact with rotor.

Sounds like you've just about replaced everything else that could be causing the issue. By the way, what brand caliper did you use? I might consider replacing mine.