Rear Caliper Piston won’t compress enough after maintenance mode (2018 CX-5)

[CoxHazards]

2018 Touring AWD

The piston on the right rear compressed but it won’t compress enough for the 2 new pads and rotors, around 1 mm short of what I need to fit the caliper back on.

The car was on jacks. I flushed the brakes then put the car in maintenance mode (I audibly heard the EBP motors disengage), then took the calipers off to replace the rotors and pads, the compression tool only slid the piston a bit, it doesn’t go all the way back in no matter how much force I put into it. I even cracked the bleeder to see if that would help, it did not.

If it helps I do get an E-brake error only when I engage auto hold feature, the feature works but if I park with the feature on the next time I turn on the car I get an error about ebrakes being disabled.

For now I put one new pad and one old pad (I know this isn’t a good solution) on to get it put back together for now.

I’ve seen threads where people take off the ebrake assembly from the caliper and finesse it, if there a good guide or video for that? Even though I put it in maintenance mode it seems like that’s my issue…

 

[HyFlyer]

Bummer. Just checking the simple solutions first .... Are you sure the replacement pads are correct? Are they Mazda OEM or aftermarket?

Does the caliper piston appear to be fully in flush with caliper body? Or sticking out a bit?

 

[CoxHazards]

Bummer. Just checking the simple solutions first .... Are you sure the replacement pads are correct? Are they Mazda OEM or aftermarket?

Does the caliper piston appear to be fully in flush with caliper body? Or sticking out a bit?

It’s aftermarket, the piston poke out and isn’t flush. I’ve confirmed that it’s not pad or rotor issue because I just did the rear left and the piston compressed enough for me to install the new pads and rotor, so one side is fine but the other side is bad. Now I wonder what the solution is, if it’s to get a new caliper that sucks.

 

[HyFlyer]

There are members more knowledgeable than me about this here but IIRC, in some of the resolutions to rear caliper problems, people have unbolted the electric motor and turned the adjustment mechanism manually.

Anyone have some shop manual descriptions for the right rear brake on a 2018?

 

[yrwei52]

2018 Touring AWD

The piston on the right rear compressed but it won’t compress enough for the 2 new pads and rotors, around 1 mm short of what I need to fit the caliper back on.

The car was on jacks. I flushed the brakes then put the car in maintenance mode (I audibly heard the EBP motors disengage), then took the calipers off to replace the rotors and pads, the compression tool only slid the piston a bit, it doesn’t go all the way back in no matter how much force I put into it. I even cracked the bleeder to see if that would help, it did not.

If it helps I do get an E-brake error only when I engage auto hold feature, the feature works but if I park with the feature on the next time I turn on the car I get an error about ebrakes being disabled.

For now I put one new pad and one old pad (I know this isn’t a good solution) on to get it put back together for now.

I’ve seen threads where people take off the ebrake assembly from the caliper and finesse it, if there a good guide or video for that? Even though I put it in maintenance mode it seems like that’s my issue…

This write-up may help:

《Guide》How to rebuild 2017 CX-5 Rear brake piston (didn't put into maintenance mode)