Replacing rear brake pads on a P+

[Dangerous Fish]

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]

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]

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]

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]

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]

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...

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.

 

[SD_Engnr]

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.

What was the manual method that you applied?

 

[Davidss2]

What was the manual method that you applied?

You remove the motor and use an allen key or star (can't remember which). There is another thread on here with pics.

 

[SD_Engnr]

You remove the motor and use an allen key or star (can't remember which). There is another thread on here with pics.

Ah, ok. Was hoping there was some other method. Thanks!

 

[MasterC17]

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.

 

[SD_Engnr]

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.

Link or info?

 

[Davidss2]

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.

Have you tried this?

I think it could be done with alligator clips or paperclips.

 

[SD_Engnr]

Have you tried this?

I think it could be done with alligator clips or paperclips.

Good point. I might have to give this a shot.

 

[Dangerous Fish]

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]

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]

Oh OK, so just the standard harness. Who's going to be the first to try the battery & clip method then?

 

[SD_Engnr]

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...