Rear Pad Job - Retracting the e-brake?

[mk5_ricola]

A little confused on the procedure for the rear pad replacement.
I saw a video where the person retracted the piston by rotating it with pliers.

I've also heard you can put the e-brake in service mode on BMWs. Is this something we can do to avoid rotating the piston back manually? Or am I misunderstanding the procedure?

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[razorlab]

Use something like Bimmerlink to unlock the piston so you can unwind it. Or... you can just unbolt the parking brake motor from the side of the caliper, unwind the piston then reattach the parking brake motor.

The pistons aren't like the front calipers where they just slide in/out, they turn.

 

[Traxion]

I leave the E-brake off and don't use service mode and I'm rotating the piston in manually. My most recent rear brake change, I decided I wanted to see if service mode helped at all and it basically did nothing. I still needed to rotate the piston back in manually. It did not retract the pistons.

 

[razorlab]

I leave the E-brake off and don't use service mode and I'm rotating the piston in manually. My most recent rear brake change, I decided I wanted to see if service mode helped at all and it basically did nothing. I still needed to rotate the piston back in manually. It did not retract the pistons.

I found out that while that works on my 2020 Supra, it does not on my 2023 M240i with the exact same calipers. You can only rotate them about one full turn until they lock.

 

[mk5_ricola]

Interesting, last time I did the pads, I did not use service mode, nor did I take off the e-brake motor to rotate it back in. Was hoping I could avoid that painful procedure of twisting it back in.

I guess there's 3 ways of doing it: service mode, unbolt the motor, or twist the piston
Thanks for the help!

 

[AHP]

I bought a chinesium caliper compression tool kit on Amazon and it works fine on my '24. It uses a disk with pins that rotates the piston while compressing it. I leave the e-brake disengaged and no special modes or other tools, etc..


https://www.amazon.com/dp/B01FW3U26G?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_8&th=1

 

[razorlab]

I bought a chinesium caliper compression tool kit on Amazon and it works fine on my '24. It uses a disk with pins that rotates the piston while compressing it. I leave the e-brake disengaged and no special modes or other tools, etc..


https://www.amazon.com/dp/B01FW3U26G?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_8&th=1

I have the same one. Make sure you keep it covered with oil or wax, or it will be covered with rust.

 

[mk5_ricola]

Gotcha, thank you all for the help!

 

[willster419]

I recently performed a front & rear rotor/pad job and wanted to share my findings as I worked through the process (2022 3.0 Premium). I found this (and a couple other) threads that had conflicting information and some parts didn't line up.

I watched a few videos about how to do the procedure and saw different methods. I have BimmerLink and decided to try using that for the work.

After releasing the parking brake and jacking up the car, I put the car into diagnostic mode (no foot on brake and rapid press start 3 times i believe). I connected my obdlink cx adaptor and used BimmerLink to put the car into service mode. I heard the motor whirling for a few seconds, then it stopped.

Fast-forwarding to having removed the wheel/pad/bracket/rotor, I found that the piston had already been fully retracted. I watched a video of a guy retracting the pistons with a clockwise motion with pliers. I tried to move it that way and it did not budge. I moved it the other direction, and it moved, then moved it back. That confirmed for me that the BimmerLink service mode fully retracted the piston. I only needed to use my caliper service tool to push the piston back in the rest of the way.

When I finished the work and put the car back down, I took the car out of service mode and heard the whilring again in one direction, then another. At that point the car was operational and I was able to engage the parking brake without issue.

I hope this helps someone else in their rear pad job.

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