2013~2016 Reassemble rear caliper piston with EPB?

Long story short, I'm in a bit if a pickle. I ended up remembering to put the parking brake into service mode AFTER removing the caliper, and the process requires you to step on the brake pedal, so it pushed piston to it's travel limit and bound it up. In a fit of despiration, a backed the small nut off the backside of the caliper until everything came apart. Reassembly seems straightforward enough, other than a small circlip that I can't figure out the proper location or installation of. Any advice, guidance, or diagrams? Should I just bite the bullet and order a new caliper?

https://photos.app.goo.gl/Khffe6n8y9CeHrTF8
 
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Long story short, I'm in a bit if a pickle. I ended up remembering to put the parking brake into service mode AFTER removing the caliper, and the process requires you to step on the brake pedal, so it pushed piston to it's travel limit and bound it up. In a fit of despiration, a backed the small nut off the backside of the caliper until everything came apart. Reassembly seems straightforward enough, other than a small circlip that I can't figure out the proper location or installation of. Any advice, guidance, or diagrams? Should I just bite the bullet and order a new caliper?

https://photos.app.goo.gl/Khffe6n8y9CeHrTF8
Any reason why you disassembled your rear caliper? And did you do only one side?

One of the nightmare when we take apart something and found there're some parts left when we put everything back! If you couldn't figure out where that circlip is supposed to go, you shouldn't want to use this caliper as it's safety related component. Rear brake calipers from factory on your 2016 CX-5 are suspect to have EPB dragging issue, and Mazda now use revised rear calipers to replace the factory ones based on a TSB. I guess you should get 2 revised rear calipers to prevent EPB dragging issue happening.
 
Any reason why you disassembled your rear caliper? And did you do only one side?

One of the nightmare when we take apart something and found there're some parts left when we put everything back! If you couldn't figure out where that circlip is supposed to go, you shouldn't want to use this caliper as it's safety related component. Rear brake calipers from factory on your 2016 CX-5 are suspect to have EPB dragging issue, and Mazda now use revised rear calipers to replace the factory ones based on a TSB. I guess you should get 2 revised rear calipers to prevent EPB dragging issue happening.

I only did one side because I was changing rear pads, and never made it to the other side of the car after hitting this roadblock. I took it apart because the I pushed the brake pedal (to put it into service mode) while the caliper was off the bracket, and the piston went to full extension. I couldn't get leverage or my retraction tool in the space remaining to force it back in. I tried removing the EPB unit and turning the small nut on the backside of the caliper in hopes of retracting it. Did not realize I needed to turn it CLOCKWISE to retract, and the whole piston eventually came out of the caliper body.

Dealer has the new caliper body in stock. Guess I'll pay the idiot tax and move on with life.
 
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Or have a mechanic who is familiar put it back together? Ed

I'd rather just pay $200 at the dealership than calling/ubering all over town trying to find someone willing and able to get the existing lot back together. The financial hit stinks, but it's not the end of the world, and is probably the path of least resistance to getting the car back on the road ASAP.
 
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I only did one side because I was changing rear pads, and never made it to the other side of the car after hitting this roadblock. I took it apart because the I pushed the brake pedal (to put it into service mode) while the caliper was off the bracket, and the piston went to full extension. I couldn't get leverage or my retraction tool in the space remaining to force it back in. I tried removing the EPB unit and turning the small nut on the backside of the caliper in hopes of retracting it. Did not realize I needed to turn it CLOCKWISE to retract, and the whole piston eventually came out of the caliper body.

Dealer has the new caliper body in stock. Guess I'll pay the idiot tax and move on with life.
No, you can't turn the piston to retract.

Maintenance Mode for 2016/2017 CX-5 electronic brakes

And since the factory rear calipers on 2016 CX-5 do have problems for EPB dragging issue, sometimes even lock the brake up, you should get BOTH rear calipers replaced with newer revised version.

TSB R052/16C: Noise from REAR BRAKE/Trace of Rear Brake Dragging
 
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There is a potential issue with turning the nut too much in that it can ruin the caliper. The early workshop manual said 2-3 turns clockwise when one is the maximum.

Warning, for this contemplating pad renewal, you should only use the maintenance mode and this manual method is for flat battery or no power.
 

Attachments

  • Caution when performing Electric Parking Brake (EPB) Forced Release.pdf
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There is a potential issue with turning the nut too much in that it can ruin the caliper. The early workshop manual said 2-3 turns clockwise when one is the maximum.

Warning, for this contemplating pad renewal, you should only use the maintenance mode and this manual method is for flat battery or no power.
Another good document saved. Thank you!
 
PXL_20240107_195132477.jpg

I took the daredevil route from this same bad spot and reassembled the caliper. The Circlip goes on the threads - that much I'm sure of. The exact location and direction of the clip are just educated guesses, but I put it on with the little protrusion last, effectively pushing the clip onto the threads. I threaded it only 3-4 times around, as the female threaded pipe in the caliper housing has little notches to catch that protrusion and those govern where the circlip ends up when the rod is threaded into the pipe.
PXL_20240107_204132899.jpg

Once the internal portion of the EPB was threaded in (all the way but don't tighten) I slid the boot to the other end of the piston so it stuck off a bit and I could seat it without risking damaging it. Make sure to POUR BRAKE FLUID INTO THE CALIPER before putting the piston back in, or you'll be bleeding the line for a week. Seat the boot, push the piston down and wiggle the EPB shaft to make the piston line up, then slide the boot back into the original trench in the piston and push the piston down all the way. Reassemble the caliper the normal way, bleed and test. So far both the pedal and the EPB are working perfectly for me.
 
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