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Changing brake pads on WRX

229K views 152 replies 72 participants last post by  15WREX 
#1 ·
Changing brake pads

My front brake pads finally gave up the ghost this last week at ~18,000 miles. While I was changing them, I noticed that the pads are retained a little differently than all the other vehicles I have worked on. Henceforth, it seemed like it might be worthwhile for me to document the procedure...
 
#6 ·
3.

At this point you can pull the pads free. I just carefully wedged my finger between the rotor and the pad to lever them free. They locate/remove in a manner perpendicular to the axis of the rotor. There are two of them on each side; remove them both. :rolleyes:

You will note that the inside pad has a metal 'clip' attached to it. The purpose of this is actually to rub against the rotor when the pad material is getting worn low; thus creating the horrid metallic squeal that will remind you your brakes need attention.
 
#15 · (Edited)
9.

It is now time to replace the caliper. If your old pads were badly worn as mine were, you will now notice that the caliper pistons are too far extended to allow you to relocate the caliper.

At this point, remove the cap from the brake reservoir. Now you are going to depress both pistons. To do this I used the lug wrench lain across the two pistons, and pushed on it with both hands. I made a rocking motion from one piston to the other until eventually they were both fully depressed. You can brace the caliper against the strut so that you can get a decent amount of force onto the caliper. While you are doing this, it is important to periodically check the level of the brake fluid in the cylinder. Brake fluid is extremely corrosive and is the best paint remover there is - you don't wan't it splashed around in your engine bay.

If you cannot get the pistons depressed, you will need to release pressure (and fluid) from the system by opening the caliper bleed screw (with a hose attached and appropriate catch can ready). This will allow you to easily depress both pistons, BUT will absolutely necessitate a bleed of the brake system afterward. You may also have to follow this procedure if depressing the pistons causes the reservoir fluid level to get too high and you do not feel comfortable trying to soak up the excess with a paper towel (CARE NOT TO DRIP BRAKE FLUID ON THE PAINTWORK).

Once the pistons are fully depressed, relocate the caliper and replace the two bolts.
 
#22 ·
Thanks for the instruction. I have a basic question. I have never changed my brake pads because I thought the brakes needed to be adjusted. But I'm pretty good with taking stuff on and putting them back on. Are there any adjustments necessary? Will the pedal distance be the same afterward? What about the handbrake adjustment? What is bleeding the brake line?
 
#23 · (Edited)
Prince Ali said:
Thanks for the instruction. I have a basic question. I have never changed my brake pads because I thought the brakes needed to be adjusted. But I'm pretty good with taking stuff on and putting them back on. Are there any adjustments necessary? Will the pedal distance be the same afterward? What about the handbrake adjustment? What is bleeding the brake line?
Assuming you have not disconnected any part of the closed hydraulic system, nothing will need to be 'adjusted'. After installation, just pump the pedal a few times with the motor running and you'll be good to go. However, if you loosen one of the bleed screws to enable you to push the pistons home, then you will need to bleed air out of the system when the installation is done.

I don't have much faith in the 'one man' bleed hoses, so I use the tried and tested 'two man' method:

1. With your car still up on the jack stand and the wheel removed, have a buddy get in the vehicle and start it. (Please make sure it's not in gear when he releases the clutch.)
2. Remove the cap from the brake fluid reservoir.
3. Attach a tightly fitting piece of clear hose over the bleed nipple.
4. Put the other end of the hose in a plastic cup that contains fresh brake fluid. Make sure the end of the hose is submerged.
5. Open the bleed nipple with your wrench...
6. ...immediately tell your buddy to push the brake pedal to the floor and hold it there.
7. Tighten the bleed nipple.
8. Tell your buddy to release the brake pedal.
9. Keep an eye on the level of fluid in the reservoir. Top up if necessary.
10. Repeat 5 through 9 until the fluid coming out is clean and has no air bubbles in it. Can be anywhere from 3 to 10 repetitions depending which parts of the system were disconnected and for how long. If you just loosened the bleed screw, you will probably not do more than 5 reps.

-Pace
 
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