Rear Brake Job - 6th Gen

[aki334]

I recently went through servicing the brakes, front and rear. This is part of routine maintenance, but I was taking care of a some squealing in this case.

 

This isn't intended as a DIY, just meant for those who have done brakes and want to see what the rears look like on this car. Not going through how to lift and support the car, etc. The front is a typical front disc brake setup, so not getting into that. Pictures were taken after the job was done - didn't think of it.

 

A couple of things you'll want to know for the rears with the electronic parking brake. First, I STRONGLY recommend disconnecting the battery - it sucks and will reset some stuff (maintenance screen for example), but I wouldn't mess with that. FSM confirms this is necessary. Alternative is to have a Subaru Computer...yeah....

 

Next, you will want a 14mm for the caliper mounting brackets and a 7mm hex for the caliper slide pin bolts. There is a little rubber cover to pop off the caliper pin bolts to access them (flat head screwdriver).

 

Before removing the caliper, it may be worth removing the one bolt that holds the brake hose in place. There is limited movement of the caliper without taking off that bolt. I did it without freeing it up, but the FSM says to remove it. Also, you will want to disconnect the electronic parking brake harness on the bottom of the caliper (sorry I didn't get it pictured, but just a pinch/pull connector).

 

To compress the piston, you will not be able to just compress or use a dice-style tool. You will need a legit disc brake pad caliper service tool kit to rotate the piston back in. Mine is from Harbor Freight. If I remember correctly, it was the size 7 that was needed.

 

There is also the retention clip on the caliper. I just used a flat-head to remove and pliers to put them back on and gently hammered it back into place so it seated nicely. I took a picture there so you can see the orientation if needed.

 

I didn't replace pads or rotors. This is with about 25K miles on them.

 

Hope this helps the next person. Really a simple job considering the electronic parking brake. BMW's version of this is insane!

 

 

Thank you Sir for taking your time to do this for us, every information is valuable we need more post like this.

[Lttlwing16]

Any fault in replacing the rear brakes with Raybestos pads/rotors and leaving the stock subaru pads and rotors on the front for a while?

 

I ordered and received all the parts for front and rear, but when I rotated my tires today the pads on the front have quite a good bit of life on them.

[ammcinnis]

I recommend that you go ahead and do all four corners. Doing only the rears is bound to alter the F/R braking balance somewhat. How much difference is too much? You're the test pilot!

[Lttlwing16]

I recommend that you go ahead and do all four corners. Doing only the rears is bound to alter the F/R braking balance somewhat. How much difference is too much? You're the test pilot!

 

The fronts look to have about half their pad life left!

[ammcinnis]

The fronts look to have about half their pad life left!

It's not about pad thickness; it's about the different friction characteristics of different pads from different manufacturers.

 

Ever wonder what brake pads are made from? It's as much art as it is science. Below is one recipe for semi-metallic pads from Wagner.

 

Sounds like you may already have your mind made up, though.

Edited September 16, 2021 by ammcinnis

[Lttlwing16]

It's not about pad thickness; it's about the different friction characteristics of different pads from different manufacturers. Sounds like you already have your mind made up, though.

 

Nah --sorry to make it seem so-- I think you're making a valid point. I already bought the stuff to do front and rear, so had planned on doing it. Just hard to know I'd be removing brake parts with half their life left.

 

-- If I were to replace the rear with Subaru oem parts, then the friction characteristic would match, and it would be less likely to cause issues?

[Lttlwing16]

Another couple questions from reading through the service manual.. On BR-32 the manual shows a diagram of the caliper assembly flipped over on top of the rotor with the caliper support lower bolt removed and the upper one loosened.

 

 

1) Is the caliper assembly secured to the caliper support with the upper 7mm hex bolt ? Was this removed and then placed back in once the caliper assembly was flipped over, or is it okay to just loosen the top caliper bolt (7mm hex) and flip the caliper over with the bolt still in?

 

2) The service manual explicitly states "Do not remove the parking brake actuator unless system malfunction or when the caliper is replaced" .. however, in the Rear Disc Brake Assembly instructions step 5 states to "remove the parking brake actuator". So I assume step 5 can be skipped unless removing for system malfunction or caliper replacement?

 

Removal of rear disc brake assembly is listed as the first step if the SSM cannot be used, list on BR-32. One Youtuber states removing the EPB actuator prevents damage to the actuator by manually cranking it in with it attached. See the comments here:

.. ** note one user commented that they had ECU problems after removing the EPB actuator Edited September 16, 2021 by Lttlwing16

[hkshooter]

ammcinnis and I are going to disagree here, respectfully.

I see nothing wrong with replacing the brakes that are worn while leaving the other axle alone. I've never heard of this friction difference thing, sounds like something that might apply to racing cars but not the street.

By design there's a difference in amount of pressure applied to each axle when the brakes are applied, normally more front than rear since the front is where the majority of the braking power is. Subaru seems to be either biased more pressure in the rear, or applying the rear a little sooner than the front, wearing them out faster than the front.

With such a bias in front to rear braking, how can equal friction become a thing?

Call me skeptical.

All my life I've replaced the worn brakes when they needed it and not bothered the axle with lots of life left. Never had any sort of issues what so ever. Even did this on my 2016, no issues what so ever.

Shops that I've had inspect brakes have done exactly the same thing and they are constantly looking for more of my money to spend. Finally, my own Subaru dealer inspects brakes every time I get the car serviced and they tell me what axle may need brakes soonest, with zero regard to doing all four because of "friction" differences.

[DougKelly20]

FWIW I think the rears wear out a little more lately because of the "torque vectoring" (misnomer) action they are trying to achieve in tight corners by dragging the inside rear wheel. I don't know if the more aggressively you drive the more you'll see this, but when I replaced mine the backs were also significantly lower than the fronts.

However

I only replaced mine because of a track day, not because it was required.

 

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[iyalla]

Yep, but its not just the torque vectoring, there is a bias to the rear brakes in cars over the last 15 years or so for safety reasons, and its only getting more pronounced in newer cars. One of the major advancements in braking came in the early 00's, EBD (electronic brake-force distribution). EBD is also one of the major reasons the rear brakes wear out quicker.

 

I change the rears twice for every one of my fronts on my cars. With EBD in every car, unintentionally introducing brake bias with a different set of pads is a thing of the past, the computer will compensate.

[ammcinnis]

I think the rears wear out a little more lately because of the "torque vectoring" ...

According to Subaru, torque vectoring in a turn works by applying light braking pressure to the inside front wheel, not rear.

"Available Active Torque Vectoring proactively brakes the front inner wheel in certain turning scenarios, improving turn-in, reducing understeer, and helping the vehicle to follow the driver’s intended path."

TV is activated only when the yaw rate in a turn is less than expected for a given steering angle and road speed.

Edited September 17, 2021 by ammcinnis

[WILLINH]

My rears only last about 50,000K and the fronts I just replaced at 101,000 K. I believe the rear also has a smaller pad.

[Lttlwing16]

Hey everyone I just finished the rear brakes and wanted to thank everyone for their input. I also wanted to write a few things I learned while working.

 

I followed the Service manual workflow and did *not* have or use a SSM/OBD to enter brake mode, instead disconnecting neg from battery sensor/unplugging EPB, and manual winding the piston back in. I had no issues after re-install. I used Raybestos Element3 rotors and pads from Rock Auto.

 

1) I found I did not need to manually compress the caliper piston after it stopped winding. It screwed all the way in for me.

 

2) The caliper piston winds right to go in for both the driver and passenger side. No need for separate LH and RH caliper tools. I flipped the caliper assembly over on top of the rotor and attached to the caliper bracket which had the lower bolt removed and upper bolt loosened to allow the caliper bracket to rotate upwards as far as possible. This was described in the service manual.

 

3) If replacing rotors, the service manual describes aligning the lug bolt marked with a black paint on the face with a small dot on the rotor. First, the paint will come off with brake cleaner so cover it with a lug nut before spraying anything down. Second, if using non-subaru replacement rotors, align the holes on the hubs and use the stock rotors to mark the new rotors, then install aligned with the marked bolt. Not exactly sure what difference this makes but there it is.

 

Other than that, pretty straight forward brake job. Only thing I did different from the service manual was to pull some brake fluid out of the reservoir then add it back afterwards.