Mazda 3 - Rear brakes question

My GF had her 2017 Mazda 3 (Sport, 2.0L, 6MT) at the dealer yesterday for a recall and to install the Android Auto upgrade. They advised that the rear brakes were pretty worn; she declined the work, knowing that we could take care of it. Parts look fairly cheap, but I don't have a shop manual for the car, and I don't want any surprises once I dig into it. Online information is surprisingly scant and unclear, perhaps because there are multiple variants of the brake setup depending on where the car was built (Japan or Mexico; hers is Mexico) and if it has the electronic parking brake (hers does).

I'm finding some indications that the rear calipers require the piston to be screwed back in rather than pressed - does anyone know precisely what tool I need to accomplish this? How does the EPB factor into this, if at all? I saw something about a "maintenance mode" for some other concurrent Mazda products, but nothing for the 3.

Finally, do we have any preferences regarding the commonly available RA brake brands?

For the tool harbor freight has a caliper piston tool set.  There are other variants on the market too including a cube thing with pins that you can get at any parts store.  Usually you retract the piston till it spins freely.  Then use the parking brake multiple times to reextend them

How many miles on this car?? I would personally check them before buying new pads. 

My experience is that rear pads wear at a waaay slower rate than fronts. 

In reply to Slippery :

45k miles. The rears are somewhat more worn than the fronts, though hardly "almost metal-on-metal" as suggested by the dealership. I figure I'll do them at some point between now and 50k. Parts are cheap enough that there's no need to wait until they're completely done.

OK, finally got to pull the rear brakes apart, and ran into a problem. I bought the little cube thing, but it turns out the piston on these needs a three-pin tool, so the cube doesn't work. I can't find any good info on what tool is needed, let alone where to buy one. There is shockingly little clear information out there about these cars. In any case, if anyone can point me to the right tool for this, I'd very much appreciate it.

Looks like this one might work?

FCP Euro piston retract tool

If you need it right away then I would try Harbor Freight.

Look like a good option would be to use a large screwdriver or piece of flat stock. 
 

if you place it into two of the grooves you should be able to turn it until you can access the third groove. 

Looks like Advance Auto sells them too:

Caliper tool

Thanks for the links. The only thing that worries me is that none of the tools indicate that they work on the Mazda, nor do they list a diameter, so there's a chance they won't fit properly. And of course I can't find anything that does explicitly state that it fits the Mazda. It sure seems they don't want people working on their own cars.

In reply to 02Pilot :

For $10 its worth a shot!

And I just found an answer to a question on Amazon for the CTA tool from the manufacturer that says it is not specified for the Mazda 3. That doesn't mean it doesn't fit, but it sure suggests it's not likely. I may still grab one - as you say, it's only $10 - but I'm still actively looking for other options.

EDIT: Found this that looks to be adjustable and should fit. The only question is how well it holds the adjustment under torque.

When I had a Mazda3 and did the brakes, I screwed mine in with angled needle nose pliers. Really. 

Unless you're getting a lot of corrosion on them, they should screw in pretty easy when the cap is off of the brake resivoir.

Brett_Murphy said:

When I had a Mazda3 and did the brakes, I screwed mine in with angled needle nose pliers. Really. 

Unless you're getting a lot of corrosion on them, they should screw in pretty easy when the cap is off of the brake resivoir.

But did you have the 3-pin setup? Mazda seems to have changed to it somewhere around 2016-2017; before that it was a 4-pin, at least if the diagram I found for a 2014 is to be believed. Also, this car has an electronic parking brake, which may or may not affect how hard it is to screw in the piston.

I don't recall, but if they document a change then I probably had the 4 slot setup.

I'd try it, myself.

Brett_Murphy said:

When I had a Mazda3 and did the brakes, I screwed mine in with angled needle nose pliers. Really.

This ^. That’s all I’ve ever used for that style of retraction (RX7). They don’t usually need much force. My guess is that you’re overthinking this job.

I tried moving the piston - there was resistance, even with the bleeder open. I didn't force anything, and perhaps this was for the best. I just found this little tidbit; while it doesn't specifically refer to the 3, it certainly suggests that there's more to the job when the electronic parking brake is involved. Excerpted:

Mazda integrated EPB system caliper servicing without a scan tool

Mazda provides a non-scan tool option for 2016/2017 CX-5s to retract the integrated caliper back for service, that is very similar to the process for Fords. This procedure can be followed to enter maintenance mode.

Entering service mode:

1. Switch the ignition ON, and don’t touch the brake pedal (the engine must be off throughout the procedure).

2. Release the EPB. Note Steps 3 and 4 must be done within five seconds.

3. While simultaneously pressing the accelerator pedal down fully, and pressing the EPB switch and holding both, switch the ignition OFF. You need to hold both the accelerator and EPB switch in this position during the next step.

4. Switch the ignition ON, while maintaining the depressed pedal and EPB switch.

5. If you have done everything correctly you should hear the caliper motors retracting. The yellow parking brake symbol with exclamation point will now be illuminated, indicating you are now in maintenance mode.

6. Switch the ignition off.

NOTE: Mazda does not want the piston rotated when servicing the caliper, just pushed back. Rotating the piston may damage the caliper internal parts.

Exiting service mode:

1. Switch ignition ON, engine off. Note Steps 2 and 3 must be done within 5 seconds.

2. While simultaneously pressing the accelerator pedal down fully, and pressing the EPB switch and holding, switch the ignition OFF. You need to hold both the accelerator and EPB switch in this position during the next step.

3. Switch the ignition ON, while maintaining the depressed pedal and EPB switch.

4. You should hear the caliper motors performing the automatic adjustment and the yellow warning light should go out, indicating maintenance mode has ended.

5. Switch the ignition OFF.

Volvo with electric parking brake, it's way easy to unbolt the motor off the back of the caliper and use a torx socket to wind it back.

That is so strange. The cube worked for my girlfriend's 2015! An aside, Mazda brakes seem to be really annoying with the way you need to angle the brake pads into their guide channels on the caliper. Took me forever to get the pads to slip into place with the new hardware not sitting perfectly flush...

I just did the rear brakes on my 2016 Mazda3 which was built in Japan. It has the 4 prong piston, not 3 like yours is. It also has a manual parking brake.

In the past on screw-in pistons I would just use pliers/vice grip pliers and never had much issue. With the Mazda3s, I was unable to get the piston to screw in it just kept spinning. 

Eventually I went and rented a caliper screw in kit (not the cube) which puts pressure on the piston while turning it and it was a piece of cake.

In case you haven't already, remove your fluid reservoir cap before trying to spin the pistons in. Good luck!

Just to follow up on this, the procedure I listed above for putting the EPB in service mode does indeed work, with one slight modification. To terminate service mode, you must lift up on the parking brake switch rather than pushing it down as stated above. Otherwise, it's straightforward. Pistons press in easily with pliers; no rotation necessary.

Glad you got it sorted. 

And the reason it has three slots is so you don't try to reef the piston back in with a standard 2 tang thread-in tool.

Happy to see that Mazda has a non-scantool method.  Most manufacturers don't.

Knurled. said:

And the reason it has three slots is so you don't try to reef the piston back in with a standard 2 tang thread-in tool.

Agreed, though it does make me wonder why they bother with the notches on the piston face at all. They don't seem to serve any purpose.