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sprinkles08
sprinkles08, ASE Certified Technician
Category: BMW
Satisfied Customers: 22110
Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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I have a 2012 BMW 550i X-Drive and I'm replacing the rear

Customer Question

I have a 2012 BMW 550i X-Drive and I'm replacing the rear rotors an pads.
The rear calipers have a electronic Actuating motor that appears to be an electronic emergency brake. The part # ***** it is TRW 32345699. When I bring this up on the internet, it shows the entire caliper with the electronic motor.
I am not wanting to push in the caliper piston as I feel confident it will somehow harm this electronic motor.
Can you give me any information on the procedure to get the caliper piston in with out damaging the motor. Any info is appreciated.
Thanks, Scott
Submitted: 1 year ago.
Category: BMW
Expert:  sprinkles08 replied 1 year ago.

Hello and welcome to JustAnswer!

You're correct, this is an electronic emergency brake and the pistons cannot be pushed back freely like a conventional caliper. To retract the caliper pistons on a vehicle with an electronic emergency brake a scan tool is used. A factory scan tool or high end aftermarket scan tool capable of communication with the module that controls the system will need to be connected, and the pistons are commanded to retract to the installation position.

Customer: replied 1 year ago.
Well, I appreciate you answering the question, but you are along with a ton of others, incorrect. You can take the electronic motors off the back of the calipers with 2 torqus screews and then retract the piston by twist in the piston and adding slight pressure. Then putting the motors back on. Once I completed the brake replacement, I cycled the electronic e-brake multiple times and all worked perfect. I found one other person that said they had done this on the web and they had success too. All has been good. I had them finished prior to even receiving your answer. I don't know if this is the correct proceedure per the dealer specs, but saved me about $700. I also use an aftermarket ceramic pad and the unbelievable brake dust it had with the factory pads went away almost completely. Thanks for responding.
Customer: replied 1 year ago.
I will add some photos of the process.
Expert:  sprinkles08 replied 1 year ago.

The calipers should never be disassembled and it's unsafe to do so, which is why I or noone else could or would recommend it. The correct and only acceptable way per any service information to retract the caliper pistons is with a scan tool.

Customer: replied 1 year ago.
I totally understand your position on this and am quite satisfied your answer was the correct one for what you felt was the proper one to give. I only gave you this information for your own personal future knowledge. The caliper was never disassembled. The motor was removed from the rear of it and doss not interfere with the hydronic system. I am a past ASE tech and would do more than the average. I mainly wanted to pass this on as I thought you might enjoy. Again, thanks for your time. I think the correct answer is it is possible which I've proven but maybe not recommended. I hope you like the photos.
Expert:  sprinkles08 replied 1 year ago.

Removing the motor from the caliper is disassembling the caliper, no parts are intended to be removed from it.

I'm glad you got it repaired and thanks for the update!

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