I tried replacing the rear brake pads on my 2005 Mazda 3, and I can't get the piston to push back. E-brake off, using c clamp. Is there any trick to this. This is happening on both sides.

 

NOOOOOOOOO. Do not try to compress with c-clamp or you will destroy the caliper. On the backside of the caliper you will see 2 14mm head bolts. One holds the parking brake bracket on. The other is just a plug. Remove that plug and there is a gear inside that you will need to turn counterclockwire with 4mm allen wrench to draw the piston back into the caliper. See drawings and directions below.



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Turn the manual adjustment gear counterclockwise with an Allen wrench to pull the brake caliper piston inward. (Turn until it stops.)
Replace the disc pads.


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Turn the manual adjustment gear clockwise until the brake pads just touch the disc plate. Turn the manual adjustment gear back 1/3-turn.