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Replacing rear brake pads on a P+

Dangerous Fish

Pilots the Millennium Milkfloat
Supporting Member
Jul 21, 2016
1,768
2,879
UK
Is the only way to retract the piston fully in the rear caliper to take off the parking brake motor and wind it back in?

These OE calipers haven't been designed with track days/racing in mind...
 

jmaddr

Active Member
Mar 29, 2019
1,018
1,034
Florida
I saw a YouTube of someone doing like a 20k service that put it in tow mode to pull the pads. They then pulled the electric plug so it would not re-engage (Which would be bad if the caliper is off).
 

Dangerous Fish

Pilots the Millennium Milkfloat
Supporting Member
Jul 21, 2016
1,768
2,879
UK
I saw a YouTube of someone doing like a 20k service that put it in tow mode to pull the pads. They then pulled the electric plug so it would not re-engage (Which would be bad if the caliper is off).
Yes, you have to do that to unlock the parking brake and keep it off, but because they automatically adjust for the pad thickness as they wear down, it's not possible to push the piston back fully. You have to take off the motor and wind back the mechanism manually.

I just wondered if there's an alternative method so you don't have to remove the motor each time you want to put new pads in.
 

Davidss2

Member
Jun 7, 2019
86
172
Texas
I tried retracting them electrically and then disconnecting the wire connector. But I still had to retract it manually.

I bet there is probably a way to use a battery even a 9v might work.
 

Dangerous Fish

Pilots the Millennium Milkfloat
Supporting Member
Jul 21, 2016
1,768
2,879
UK
I tried retracting them electrically and then disconnecting the wire connector. But I still had to retract it manually.

I bet there is probably a way to use a battery even a 9v might work.
This is what I'm thinking. Or maybe there's a hidden service menu where it can be done. What's needed is access to the workshop manual...
 

SD_Engnr

Active Member
Mar 24, 2016
1,836
1,520
San Diego
Is the only way to retract the piston fully in the rear caliper to take off the parking brake motor and wind it back in?

As far as I know, and based on others who have replaced pads multiple times(track rats), yes. I found that out last weekend when I went to install the factory shim on some aftermarket pads. So, when I have more time I will mess with it. For now, I get to deal with rattling brake pads... :mad:

These OE calipers haven't been designed with track days/racing in mind...

They most certainly have not. Pulling calipers to swap pads adds more time than is necessary. The non P3D+ calipers seem to be much easier. o_O
 

MasterC17

Active Member
Dec 3, 2015
1,288
2,044
USA
If you're willing, you can buy an M3 Performance jumper harness. Apply 12v and the Piston will back out. Unfortunately, jumper harness is $150 last I checked.
 

Dangerous Fish

Pilots the Millennium Milkfloat
Supporting Member
Jul 21, 2016
1,768
2,879
UK
If you're willing, you can buy an M3 Performance jumper harness. Apply 12v and the Piston will back out. Unfortunately, jumper harness is $150 last I checked.
Does this harness do anything else other than retract the rear caliper piston?
 

MasterC17

Active Member
Dec 3, 2015
1,288
2,044
USA
ASY, EPB JUMPER, LH, PERF, M3, AWD Performance 1098480-00-D

If you connect it to the rear caliper, cut off the other end and split the harness, and apply 12V to it, it will retract (or engage) the piston.

Of course, you can also use alligator clips or the like. This is just a bit cleaner.
 

Dangerous Fish

Pilots the Millennium Milkfloat
Supporting Member
Jul 21, 2016
1,768
2,879
UK
Oh OK, so just the standard harness. Who's going to be the first to try the battery & clip method then?
 

SD_Engnr

Active Member
Mar 24, 2016
1,836
1,520
San Diego
Couldn't you, in theory, trick the car to retract the piston? Put in tow mode, disconnect the caliper harness, release tow mode, reconnect harness, and then engage tow mode again. Just a thought.

In the end, it's probably easier to just pull the motor...
 

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