2008-2010 Subaru Impreza Brake Job Guide: Symptoms, Costs and the Right Parts

By Core Brake Parts Tech Team — Circleville, OH warehouse

A brake job on a 2008-2010 Subaru Impreza usually means front pads and rotors first, with the rear axle following later. The one thing to check before you order anything: a base 2008 2.5i left the factory with rear drum brakes, while other 2008 cars such as the Outback Sport have rear discs, and spec sheets for the 2009 and 2010 models list four-wheel disc brakes. Get that right and the rest of the job is a straightforward bolt-on repair.

What brakes your Impreza actually has

The 2008 model year launched a new generation of Impreza, and brake hardware changed between trims and years. That is why parts listings for this car split into "drum rear" and "disc rear" versions, and why ordering by year alone can put the wrong parts on your doorstep.

The fastest check is visual. Turn the front wheels and look through the rear wheel spokes: a caliper clamped over a flat rotor face means rear discs; a closed, round drum means rear shoes. If you have a WRX or STI, shop for those models specifically, because their rotors and pads are a different size from the 2.5i parts.

Symptoms that the brake job is due

• Squeal or scraping when braking. A high-pitched squeal that shows up as you stop is often the pad wear indicator touching the rotor. Grinding means the friction material is gone and metal is contacting the rotor, which usually turns a pad job into a pad and rotor job.
• Pedal pulsation or steering wheel shake. Uneven rotor thickness, often from pad material deposits or heat, shows up as a pulse in the pedal. On the front axle you usually feel it in the steering wheel.
• Pulling to one side. A sticking caliper slide pin or a seized piston on one side makes the car drift under braking and wears that side's pads much faster.
• Soft or sinking pedal. This is a hydraulic warning, not a pad problem. Check the brake fluid level and look for wet spots at the wheels and along the lines under the car.
• Brake warning light. A low fluid level can turn this light on, and the fluid level drops gradually as the pads wear. Do not just top it off; find out whether the pads are thin or something is leaking.

The brake line recall every owner should know about

This generation of Impreza is covered by NHTSA recall 14V-311 (Subaru campaign WQK-47). Subaru's filing covers 2008-2011 Impreza and 2008-2014 Impreza WRX/STI vehicles currently or formerly registered in salt-belt states, including Ohio, Michigan, Pennsylvania, New York and much of the Northeast and Midwest. The defect: salt water could splash onto the brake lines through a gap in the fuel tank protector and cause excessive corrosion. A corroded line can leak fluid, which lengthens stopping distance.

The remedy is a dealer inspection for leaks, rustproofing with anti-corrosion wax, and line replacement if seepage is found, at no charge. Subaru's report also notes that cars outside those states are eligible for the repair on request, and that some Impreza, WRX and STI cars repaired before December 23, 2014 needed extra anti-corrosion treatment at the four-way joint area under a follow-up recall, 14V-830. Before you do a brake job on a high-mileage northern car, run the VIN on the NHTSA recall lookup and look over the lines near the fuel tank. If a line is already weeping, fix that first; new pads will not help a leaking hydraulic system.

Front vs rear: what wears and what to replace together

The front brakes do most of the stopping on any front-heavy car, so on an Impreza the front pads normally wear out first. The rears last longer, but in salt country the rear calipers and slide pins tend to corrode and stick, so inspect them every time the wheels are off.

Front axle

Replace front brake pads as a set on both sides. Measure the rotors against the minimum thickness stamped on the rotor or listed in the factory service manual. If they are under minimum, scored, or causing pulsation, replace them with new brake rotors rather than machining thin ones. Clean and lubricate the caliper slide pins, and replace the pad clips and shims; a brake hardware kit is inexpensive and prevents most noise complaints.

Rear axle (disc)

The rear job is the same idea as the front, with one extra step. Before pulling the rotor, check how the parking brake works on your car: on many Subaru rear discs the parking brake is a small set of shoes inside the rotor hat. If the rotor will not come off, back off the parking brake adjuster rather than hammering the rotor, and check those shoes while you are there.

Rear axle (drum, base 2008 2.5i)

Drum cars take brake shoes instead of pads. Inspect the wheel cylinders for fluid seepage while the drums are off; a leaking wheel cylinder contaminates new shoes immediately. Replace springs and hardware if they are rusted or weak, and set the shoe adjustment so the drum turns with light drag.

If you are doing both axles at once, a matched front and rear set of pads and rotors keeps the friction behavior consistent front to back. Browse our full brake parts catalog for pads, rotors, calipers and hardware.

Brake fluid and the hydraulic side

Subaru's owner's manual for this Impreza calls for genuine Subaru brake fluid or fresh FMVSS No. 116 DOT 3 brake fluid. Brake fluid absorbs moisture over time, which lowers its boiling point and helps corrode the system from the inside. A brake job is a good time to flush it, especially if the fluid in the reservoir looks dark. Follow the bleed sequence in the factory service manual, and keep the reservoir from running dry so you do not pull air into the ABS unit.

When you push caliper pistons back to fit new pads, the fluid level in the reservoir rises. If someone topped it off while the pads were worn, it can overflow. Remove a little fluid first and keep brake fluid off paint, since the manual warns it damages painted surfaces.

If a caliper piston is seized, the boot is torn, or a slide pin will not free up, replace the caliper. Rebuilt brake calipers are the normal fix at this age.

How hard the job is and what drives the cost

A front pad and rotor job on a 2008-2010 Impreza is one of the more approachable brake jobs for a home mechanic: remove the caliper, remove the caliper bracket, swap the rotor, and reassemble with new pads and hardware. Rusted rotors on northern cars can be stuck to the hub and may need penetrating oil and patience. Torque every fastener, including the lug nuts, to the values in the factory service manual; do not guess.

What changes the price of the job:

• Pads only vs pads and rotors. Pads alone are the cheapest repair, but only if the rotors are above minimum thickness and not causing vibration.
• One axle vs both. Doing front and rear together roughly doubles parts and labor, but saves a second trip if the rears are already close.
• Calipers and hydraulics. A stuck caliper, a leaking wheel cylinder or a corroded line adds parts and labor fast.
• Disc rear vs drum rear. Drum service on a base 2008 involves more small parts and adjustment time.
• Shop vs DIY. Labor is a large share of a shop brake bill; doing it yourself leaves you paying mainly for parts.

After any brake job, bed in the new pads with a series of moderate stops from speed, avoiding a hard stop and not holding the pedal down while the brakes are hot. That transfers an even layer of pad material to the rotor and prevents the uneven deposits that feel like warped rotors.

Frequently Asked Questions

Does my 2008 Impreza have rear disc or drum brakes?

It depends on the trim. The base 2008 2.5i was built with rear drums, while other 2008 cars, including the Outback Sport, have rear discs. Look through the rear wheel: a caliper means discs, a round drum means shoes.

Do 2009 and 2010 Imprezas have four-wheel disc brakes?

Yes, spec sheets for the 2009 2.5i list four-wheel disc brakes. Still confirm visually before ordering, because a used car may be a different trim or may have been modified.

Can I use WRX brake pads on a regular Impreza 2.5i?

Not as a direct swap. The WRX and STI use larger rotors and different calipers, so their pads and rotors do not fit the 2.5i's brakes. Order parts for your exact model.

What brake fluid does a 2008-2010 Impreza use?

Subaru's owner's manual lists genuine Subaru brake fluid or fresh FMVSS No. 116 DOT 3 fluid.

Is my Impreza part of the brake line recall?

Subaru recall 14V-311 covers 2008-2011 Impreza and 2008-2014 WRX/STI cars currently or formerly registered in listed salt-belt states and Washington DC, and other cars are eligible on request. Enter your VIN on the NHTSA recall site or ask a Subaru dealer to confirm.

Should I replace the rotors every time I replace the pads?

Not automatically. Replace them if they are below the minimum thickness on the rotor, deeply scored, or causing vibration. Otherwise good rotors can stay with new pads.

Sources

1. NHTSA Part 573 Safety Recall Report 14V-311 - brake line corrosion recall scope, affected Impreza years, states, remedy and the 14V-830 follow-up
2. Subaru 2008 Impreza Owner's Manual, recommended brake fluid - genuine Subaru or FMVSS No. 116 DOT 3 brake fluid, paint damage warning
3. Auto123, 2008 Subaru Impreza 2.5i technical specifications - front disc, rear drum brakes on the 2008 2.5i
4. Auto123, 2009 Subaru Impreza 2.5i technical specifications - four-wheel disc brakes with ABS for 2009
5. Wilwood Brake Kit Advisor, 2008 Subaru Impreza - 2008 2.5i offered in drum-rear and disc-rear versions, plus Outback Sport, WRX and STI
6. Scoobyparts Impreza brake disc size guide - WRX vented front and solid rear discs, STI vented front and rear discs