2015-2016 Subaru WRX Brake Job Guide: Symptoms, Costs and the Right Parts

By Core Brake Parts Tech Team — Circleville, OH warehouse

A brake job on a 2015-2016 Subaru WRX means front pads and rotors most often, rear pads and rotors less often, and a fluid flush every time the system is opened. The WRX runs discs at all four corners: 12.4-inch ventilated rotors with two-piston sliding calipers up front, and disc brakes with single-piston sliding calipers in the rear. It is one of the more approachable brake jobs on a modern performance car, as long as you use the right parts and bed them in properly.

How the Brakes Work on the 2015-2016 WRX

When Subaru redesigned the WRX for 2015, it enlarged the front discs to 12.4 inches, up from 11.6 inches on the previous car, to add surface area and fade resistance, and it fitted a new master cylinder. The front rotors are vented, with two friction faces separated by cooling vanes. Both axles use sliding calipers, which float on guide pins rather than clamping from both sides with fixed pistons like the Brembo setup on the WRX STI.

The WRX also uses its front brakes for more than stopping. Subaru's Active Torque Vectoring applies slight pressure to the inside front brake in corners to reduce understeer. On a car that is driven hard, that is one more reason the front pads and rotors usually wear out before the rears.

Symptoms That Your WRX Is Due for Brakes

• High-pitched squeal while braking. Subaru fits pad wear warning indicators that make a noise when the pads are worn. The owner's manual says a squeaking or scraping noise from the disc brakes means the car should be checked right away.
• Grinding. Metal-on-metal means the friction material is gone and the backing plate is cutting the rotor. At that point rotors are no longer optional.
• Pulsing pedal or steering shake under braking. Usually uneven pad deposits or rotor thickness variation, common after hard stops followed by sitting with the brakes clamped on hot rotors.
• Longer stops or a soft pedal. Can be worn pads, but also old fluid that has absorbed moisture. Subaru warns that brake fluid absorbs moisture from the air, which degrades braking performance.
• Pulling to one side. Often a sticking caliper slide pin or a seized piston on one side.

One normal behavior to rule out: just after the car starts, you may feel a brief vibration in the pedal similar to ABS operation. Subaru describes this as the ABS self-check, not a fault.

Front vs Rear: What Each Brake Job Involves

Front axle

The front job is pads, rotors, and fresh hardware. Remove the caliper slide bolts, swing the caliper up, pull the pads and abutment clips, then unbolt the caliper bracket to remove the rotor. Clean the hub face of rust so the new rotor sits flat, because a rotor that sits crooked on the hub produces pedal pulsation within a few thousand miles. Clean and re-grease the slide pins with a brake-specific lubricant. Torque every fastener to the values in the factory service manual.

Rear axle

The rear job is similar, but the single-piston caliper piston must be pushed back to make room for thick new pads. The rear brakes also handle parking brake duty, so check the parking brake lever travel after the job and adjust it if the lever pulls up further than it should. Subaru's owner's manual gives a lever stroke check and a separate break-in procedure for parking brake linings.

Shop brake pads and brake rotors by axle, and pick up a brake hardware kit so the clips and pins are fresh too.

What to Replace at the Same Time

• Rotors with pads. Putting new pads on scored or thin rotors shortens pad life and often brings back noise and vibration. On a car this age, many original rotors are at or near their minimum thickness, which is stamped on the rotor.
• Both sides of the axle. Always replace pads and rotors as a left-right pair so the car stops straight.
• Hardware. Abutment clips and anti-rattle springs lose tension with heat cycles. New clips are cheap insurance against noise.
• Brake fluid. Flush with the grade listed in the owner's manual fluid chart. Subaru specifically says not to mix brands of fluid, and not to mix DOT 3 and DOT 4 even within the same brand.
• Calipers if a slide pin is seized or a piston will not retract. A remanufactured unit from our brake calipers collection is usually faster than rebuilding a corroded one.

Choosing the Right Parts

For a daily-driven WRX, a quality ceramic brake pad gives low dust, quiet operation, and good rotor life. If the car sees spirited driving, autocross, or mountain roads, a performance street compound gives more bite when hot at the cost of more dust. Hawk, for example, describes its HPS street pad for the WRX front caliper as offering a smooth braking feel, extended pad life, and more stopping power for spirited driving. Whatever the compound, match front and rear so the brake balance stays close to how Subaru designed it.

A complete front or rear kit with matched pads and rotors is the simplest way to get parts that fit together; browse our brake parts for kits that list the 2015-2016 WRX.

What Drives the Cost of a WRX Brake Job

The price of a brake job comes down to four things: how many axles you do, whether you replace rotors or only pads, the pad compound you choose, and whether a shop does the labor. Front pads alone are the least expensive job. Pads and rotors on one axle is the most common. Both axles plus a fluid flush is the full service. Labor is modest on this car because the calipers are simple sliding units that need nothing more exotic than a piston tool and a torque wrench. A seized caliper or a rusted-on rotor adds time and parts, so budget for surprises on a car that has seen salt-belt winters.

After the job, bed in the pads. Subaru's owner's manual procedure for new pads is to hold 30 to 40 mph and apply the brakes lightly, repeating five or more times. Avoid long, hard stops for the first stretch of driving.

Recall Check Before You Start

NHTSA campaign 15V366 covers certain 2016 WRX models equipped with the EyeSight driver assist system. If the brake light switch fails, the automatic pre-collision braking function will not work. Subaru's remedy is a free reprogramming of the driver assist system at a dealer. It does not change how the brakes respond when you press the pedal, but if your car has EyeSight, confirm the recall has been done, and replace a failed brake light switch promptly.

Frequently Asked Questions

Does the 2015-2016 WRX have rear disc brakes?

Yes. The WRX uses rear disc brakes with single-piston sliding calipers. Up front it has 12.4-inch ventilated discs with two-piston sliding calipers.

Can I use WRX STI brake parts on a regular WRX?

No. The STI uses Brembo fixed calipers with larger rotors, and its pads and rotors do not fit the standard WRX calipers. Always shop by the exact model, not just the year.

How do I know if I need rotors or just pads?

Measure rotor thickness against the minimum stamped on the rotor, and look for deep scoring, heat spots, or a lip at the outer edge. If the pedal pulsates or the pads have worn to metal, replace the rotors.

What brake fluid does the WRX use?

Use the grade listed in the fluid chart of your owner's manual. Subaru warns against mixing different brands, or mixing DOT 3 with DOT 4, and notes that brake fluid absorbs moisture over time, so it should be replaced on schedule.

Why do my new brakes squeal?

Common causes are skipped bed-in, missing or reused abutment clips, dry slide pins, or glazed rotors reused with new pads. Clean the hardware, lubricate the contact points, and bed the pads in per the owner's manual.

Sources

1. Subaru U.S. Media Center - 2015 WRX debut - 12.4-inch front discs up from 11.6 inches, new master cylinder, Active Torque Vectoring uses the front brakes
2. 2015 WRX specifications (Subaru dealer) - ventilated front disc with two-piston sliding caliper, rear disc with single-piston sliding caliper
3. NHTSA recall 15V366 - EyeSight pre-collision braking and brake light switch recall on 2016 WRX, free reprogramming
4. Subaru WRX/WRX STI owner's manual - brake fluid - do not mix brands or DOT 3 and DOT 4; fluid absorbs moisture
5. Subaru WRX/WRX STI owner's manual - pad wear indicators - wear indicators make noise; ABS self-check vibration
6. Subaru WRX/WRX STI owner's manual - break-in - new pad break-in at 30 to 40 mph, five or more light stops; parking brake stroke check
7. Hawk Performance HPS brake pad - HPS street compound characteristics for the WRX front caliper