CX-9 Rear Brake Pad Change with EPB - Don't Do What I Did!

[matadorCE]

Went to do a rear brake job on my wife's '19 CX-9 and learned some hard lessons. I've wrenched on a number of cars in the past, but this one got me.

Don't:
1) Omit the most crucial step of putting the parking brake in maintenance mode. Tip: the parking brake needs to be disengaged before trying to put it in maintenance mode.
2) Take off the parking brake motor from the caliper. Assuming you've successfully put the car in parking maintenance mode, it's completely unnecessary. I've seen this in some youtube vids and don't understand why people started doing this.
3) Engage the parking brake or press the brake pedal with the pads and rotors off!!
4) Use the little cube to try to turn the brake piston in. This will accomplish nothing and may damage the internal seal, pop the dust boot seal out, or mess up the electric motor.

Do:
1) Make sure the car is in parking maintenance mode! You should hear the motors running and the dash light illuminate. If you don't hear the motors, the e-parking brake isn't in maintenance mode
2) Resurface or replace the rotors with a pad change. I've seen vids of people just changing the pads without touching the rotors and this is incorrect.
3) Take off the caliper slider first, and then the brake piston housing. No need to remove electric parking brake motors.

If you happen to be a complete dummy like me who didn't bother to look up tutorials on how to do a rear brake pad and rotor change on a CX-9, AND happen to extend the brake piston all the way without pads or rotor and now it can't be pushed back in I have special instructions for you:
1) You'll need to remove the brake caliper from the car; no way around this. Drain the brake fluid from the caliper, remove the electric motor, and remove entirely from the car.
2) Remove the piston by hand from the caliper. It will be tight so have patience and avoid using tools that will damage the piston surface or dust boot.
3) If the internal screw that moves the piston inside the caliper has become separated from the collar, you'll need to remove the small circlip around the hex shaft in order to slide the shaft out of the caliper. You'll need a small set of circlip/snap ring pliers to do this; I got a set at Lowes that comes with multiple heads so check your local stores if you don't have this in your toolbox.
4) Assemble the internal screw into collar and screw all the way in. Slide screw/collard assembly back into the caliper. Re-install the circlip on hex shaft.
5) Lube internal seal with some clean brake fluid.
6) Slide dust boot to end of piston. The dust boot lip will need to be installed first before sliding the piston back into the caliper.
7) Align the piston into the bore and carefully push in using a brake piston tool. If done correctly and carefully, the dust boot will stay in place and you'll be able to push the piston in all the way using the brake piston tool. I would not recommend using a c-clamp since you want to align the piston in the bore as straight as possible when pushed in.
8) Reinstall brake caliper into the car attaching e-parking brake motor and brake line (don't lose the washers that go on both sides of the banjo bolt!)
9) Put in new pads, new or resurfaced rotor, and proceed to bleed the brake caliper using a vacuum pump (lots of videos available on how to do this)

Sorry that I don't have pictures since I was too pissed off, frustrated, etc and just needed to get the car back on the road asap, but I found a lot of useful info on this site as to what I did wrong, what the correct procedure is, etc so I wanted to return the favor in case anyone else messed this up in a similar way.

 

[PTguy]

Thank you for the good info. By the way, I've put new pads on used rotors, that look very good & smooth, with good results. Do sandpaper the glaze off and wash well with brake clean solvent at a minimum. If the surface is grooved or a ridge exists on the outer edge, yes either renew or resurface.

Do we know the minimum allowable thickness of the rotors?

 

[Rakenroler]

One more thing about them banjo bolt washers. Supposedly they might or may not fail if they get squeezed the second time. I always buys new ones if I remove them. Good lists overall for this guide Thank You.

 

[Jushang]

This was a very helpful post that managed to allow me to resolve this same issue when the piston fully extended out of the caliper. In my case I was not able to reinsert the piston into the caliper without fully removing the piston. In addition a small circlip had become dislodged from the shaft and floating in break fluid. I would recommend a full caliper disassembly if this situation arises. In some cases the circlip will break due to the forces involved while attempting to rotate the piston and EPB in the process. See this thread for pictures of circlip and disassembled caliper. Clip inside Rear Brake Caliper Piston - Mazda Forum - Mazda Enthusiast Forums
In general I agree with matadorCE's step to resolve this issue with a few modifications. Step 3 of removing the shaft from the collar is unnecessary. You can simply screw the internal screw into the collar while it sits in the shaft very easily. One additional step that is likely required is to thread a different circlip that may have come loose (or broken) back on onto the threaded rod per above post. Keeping in mind this circlip must be rotated to the bottom of the threaded rod in order to allow the piston to fully retract into the caliper to allow the caliper to slide over the new brake pads.
After doing these steps and screwing the threaded rod all the way into the collar as it will go proceed with step 5.

 

[Agape_365]

I have nothing to add commenting so i can look up the comment later in the history when i do my rears. As i dont know how to save this post fornlater referance.

 

[Antoine]

I have nothing to add commenting so i can look up the comment later in the history when i do my rears. As i dont know how to save this post fornlater referance.

To the right of the date on each post is a little bookmark icon…Tap that to bookmark/save the post for later reference…To view bookmarks simply tap on your avatar icon on the top menu nav bar and then tap “Bookmarks” at the top of the pop-out window…Hope that helps!

 

[PJ171]

This is awesome advice here. Curious if you've seen any Youtube videos that came close enough to work well when paired with your advice below? Always helpful to have some visual aids too.

Went to do a rear brake job on my wife's '19 CX-9 and learned some hard lessons. I've wrenched on a number of cars in the past, but this one got me.

Don't:
1) Omit the most crucial step of putting the parking brake in maintenance mode. Tip: the parking brake needs to be disengaged before trying to put it in maintenance mode.
2) Take off the parking brake motor from the caliper. Assuming you've successfully put the car in parking maintenance mode, it's completely unnecessary. I've seen this in some youtube vids and don't understand why people started doing this.
3) Engage the parking brake or press the brake pedal with the pads and rotors off!!
4) Use the little cube to try to turn the brake piston in. This will accomplish nothing and may damage the internal seal, pop the dust boot seal out, or mess up the electric motor.

Do:
1) Make sure the car is in parking maintenance mode! You should hear the motors running and the dash light illuminate. If you don't hear the motors, the e-parking brake isn't in maintenance mode
2) Resurface or replace the rotors with a pad change. I've seen vids of people just changing the pads without touching the rotors and this is incorrect.
3) Take off the caliper slider first, and then the brake piston housing. No need to remove electric parking brake motors.

If you happen to be a complete dummy like me who didn't bother to look up tutorials on how to do a rear brake pad and rotor change on a CX-9, AND happen to extend the brake piston all the way without pads or rotor and now it can't be pushed back in I have special instructions for you:
1) You'll need to remove the brake caliper from the car; no way around this. Drain the brake fluid from the caliper, remove the electric motor, and remove entirely from the car.
2) Remove the piston by hand from the caliper. It will be tight so have patience and avoid using tools that will damage the piston surface or dust boot.
3) If the internal screw that moves the piston inside the caliper has become separated from the collar, you'll need to remove the small circlip around the hex shaft in order to slide the shaft out of the caliper. You'll need a small set of circlip/snap ring pliers to do this; I got a set at Lowes that comes with multiple heads so check your local stores if you don't have this in your toolbox.
4) Assemble the internal screw into collar and screw all the way in. Slide screw/collard assembly back into the caliper. Re-install the circlip on hex shaft.
5) Lube internal seal with some clean brake fluid.
6) Slide dust boot to end of piston. The dust boot lip will need to be installed first before sliding the piston back into the caliper.
7) Align the piston into the bore and carefully push in using a brake piston tool. If done correctly and carefully, the dust boot will stay in place and you'll be able to push the piston in all the way using the brake piston tool. I would not recommend using a c-clamp since you want to align the piston in the bore as straight as possible when pushed in.
8) Reinstall brake caliper into the car attaching e-parking brake motor and brake line (don't lose the washers that go on both sides of the banjo bolt!)
9) Put in new pads, new or resurfaced rotor, and proceed to bleed the brake caliper using a vacuum pump (lots of videos available on how to do this)

Sorry that I don't have pictures since I was too pissed off, frustrated, etc and just needed to get the car back on the road asap, but I found a lot of useful info on this site as to what I did wrong, what the correct procedure is, etc so I wanted to return the favor in case anyone else messed this up in a similar way.

 

[RokkuAni]

I did what you did... I wanted to give my 2 cent and possibly of a rebuild for those who want to do it. Did this the first time fin. The 2nd time two years later I was over confident and mess up. My piston is out.

I now have a sticky sheet in red font to go over the "Do and Don't", with list of items I needed.
I added my work here to help other, having different perspectives

This part you might see on another post

So if you mess up, disconnect the EPB, you can pull the piston out. Try not to damage or turn it.

There is a small clip on the other side with Hex screw. Remove it, and everything can be pulled out.

Key note, if red clip isn't broken. Try to place it onto the blue and deep as possible.

Now do NOT place it onto caliper and try to screw it. This is picture ONE

Connect it outside and screw just a bit. THEN PLACE it inside and COMPRESS it. If you screw, the clip will come off

Once on, add back clip and play around with the boot.

Now bleeding.. . This is important, you must understand this is a lot of pumping. Like 200 pumps after I fill the caliper with the fluid. We mess up on this thinking our rebuilt was bad.

Look up how to bleed videos and on my experiences, it comes out very slowly . Then line look like you shaken a oil bottle up. Lots of micro bubbles. I heard some people would leave it for a few hours. I didn't try that method.

Not a pro, but we fixed it. Dealer wanted $400 for part as well as waiting to to be delivered. Took 7 hours, 1 hour if I didn't mess up entering service mode when it off the pads.