How do i fix the rear brakes on my mazda 3. i fail to push the piston back. how? thers no adj. screw

Rear Disc Brake Caliper ?

There is a small tool to turn the caliper pistons
in or retract (that is actually the barking brake)

You also have to push the piston in, after you screw
in the piston,for that you open the bleeder & make sure
you have something across the caliper ,so your not pushing
on the piston with any clamp or other tool

May push in by hand- IF- the bleeder is open

Lots of video you can watch on You Tube

After removing the caliper from it's mount, and If you are sure the piston is not frozen (rusted) in place, Try a very large C clamp. You should be able to compress the pistons with very little force. If not, you may need new or rebuilt calipers. Check online for more ideas by searching for Mazda rear brake repairs, you'll be surprised how much info may be out there.

rear disc brakes with e-brake in the caliper need to be screwed back in to seat pads properly

No, you need to squish the caliper pistons back into the caliper so they will fit. Take a big c-clamp and do it very slowly or you will have brake fluid all over the engine. If they are self adj, you need to turn them in with pair of channelock pliers, They will self adj back out after you get going, check it out, hope this helps.

the rear caliper have allenkey screw..first open the cover scew that cover the allenkey. and than turn the allenkey srew to move the piston..
after piston coming out, the are clip to remove the piston holder..
than remove all the part and cleaned..after that install new oil seal for hand brake lavel.. mostly the leaking come from oil seal hand barake lavel.

Give me a call.
1) I have owned a Mazda protege 5 for the last 4 years
2) I have done 2 complete brake jobs on it
3) I am a braking systems engineer.
4) I know what I am doing. I have done 100's of brake jobs on lots of different vehicles.

Biggest issue with the protege is getting the piston back in.
Look at the back of the caliper.
There is a thin head bolt on the back.
You need to take this off the caliper and reach inside with an allen head (I think it's 5mm). Then turn the set screw in there out a few turns. Then you can push the piston back in with a regular piston push back tool. Dont worry if the set screw comes out. Just thread it back in. But you HAVE to at least start it back in. It is part of the auto-adjust mechanism. After you do your brakes you may notice that your parking brake has A LOT of play. After you work it a few times it will tighten back up just fine.

Clean averything well and grease the slide pins with a good quality waterproof grease. There is special grease for slide pins.
Greg 248-219-5821

Front or rear? I am assuming rear as most people think you can just push them back. They need to be turned clockwise while pushing them in.

you cannot push back cylinder you have to wind it back using a wind back tool or if your strong enough you can use long nosed pliers to wind back piston (cylinder)

I had the same issue when I replaced mine. I can't say it is the 100% correct solution but it did work for me. Or course there is a specialty tool for the job, but I used a needle nose pliers and got in the two dimples on the piston face. You have to then push quite hard and screw it in clockwise. One of them I had to back out and in but it did work in the end. The fact they are so hard to do is probably related to the how soon my rear brakes went out (about 40K miles). Hopefully you got it, otherwise good luck. I just had to keep messing with it and it eventually came in. Also, I think if you fully extended the piston and wore the pads to metal that may also play a role in the difficulty getting the piston re-set. Once you get it going, it will pull right in as you turn it clockwise.

On the rear calipers you need to screw the piston back into place. There is a tool nicknamed a rubik's cube. That will plug into the piston and you hook up a 3/8 inch ratchet and screw it back in while pushing inward. http://www.summitracing.com/parts/WMR-W80621