2003-2007 Scion XA Front vs Rear Brakes: What Wears First and What to Replace

By Core Brake Parts Tech Team — Circleville, OH warehouse

On a Scion xA the front brakes wear out first, and usually by a wide margin. The xA uses vented front disc brakes and small rear drum brakes, and because the front axle does most of the stopping, the front pads typically need replacing well before the rear shoes do. The practical plan: measure the fronts at every tire rotation, and check the rear shoes and drums every time you do the fronts.

One note on years: the xA was sold in North America for the 2004, 2005 and 2006 model years. It shares its brake hardware with the first-generation xB, and the Japanese-market version of the car ran longer, which is why some parts listings show a wider 2003-2007 range. Everything below applies to the North American xA with the 1.5-liter engine.

How the xA brake system is laid out

Up front, each wheel has a single-piston sliding caliper clamping a vented cast-iron rotor. The rotor is 255 mm (about 10 inches) across and 22 mm thick when new. Each front pad sits in the caliper bracket on metal support plates (abutment clips) and carries two anti-squeal shims on its back.

At the rear, each wheel has a leading/trailing drum brake: a single wheel cylinder pushes two shoes out against the inside of a 200 mm drum. The same shoes double as the parking brake, operated by a cable and a lever on the rear shoe, and an automatic adjuster keeps the shoe-to-drum clearance in check as the linings wear. The factory manual specifies SAE J1703 / FMVSS No. 116 DOT 3 brake fluid for the system.

These numbers come from the factory repair manual for this platform (the xA and first-generation xB share these parts). The 1.0 mm figure is the absolute limit, not a target: most shops replace linings well before that.

Why the front pads wear first

When you brake, weight shifts forward onto the front tires, so the front brakes do most of the work. The xA is also a front-engine, front-drive hatchback, so it carries more of its weight over the nose to begin with. The front pads start with far more material than the rear shoes (11 mm against 4 mm), but they also see far more heat and friction, so in city driving they still wear out much sooner.

The rear drums wear slowly, but they have their own failure modes that have nothing to do with lining thickness:

• Leaking wheel cylinders. The rubber cups age, and fluid gets onto the shoes. A fluid-soaked shoe grabs and pulls, and it has to be replaced; cleaning does not save it.
• Stuck self-adjusters. If the adjuster seizes, the shoes drift away from the drum, the pedal gets low and the parking brake lever travels farther than it should.
• Rust and ridges. Cars that sit, or live where roads are salted, build a lip of rust on the drum edge that can make the drum hard to pull off and noisy when it goes back on.

Symptoms and how to tell which end needs work

Front brakes

• A high-pitched squeal with light braking often points to thin pads or worn or missing shims.
• Grinding means the lining is gone and steel is touching the rotor. Stop driving and inspect right away.
• A pulsing pedal or steering-wheel shake under braking usually means rotor thickness variation or runout. The factory limit for runout is only 0.05 mm, measured 10 mm in from the rotor edge.
• Pulling to one side can be a sticking caliper slide pin or piston.

Rear brakes

• A parking brake that needs more clicks than it used to, or will not hold on a hill, suggests worn shoes or an adjuster that is not working.
• A low or long pedal that firms up when you pump it can be rear shoes that are out of adjustment.
• Scraping or rhythmic rubbing from the back, or one rear wheel noticeably hotter than the other after a drive, calls for pulling the drum.
• Wetness on the inside of the tire or the backing plate usually means a wheel cylinder leak.

You can get a first look at the rear linings without removing the drum: the backing plate has a hole plug, and removing it lets you see the shoe lining. For an accurate reading, pull the drum and measure. The Scion maintenance schedule for these cars calls for a visual brake inspection every 5,000 miles or 6 months, with actual thickness and runout measurements at the 30,000-mile services.

What to replace, and what to replace with it

Front brake job

Replace pads in axle sets, both sides at once. Measure the rotors with a micrometer: under 20.0 mm, they must be replaced. Many owners replace them with the pads anyway, because it removes the guesswork about runout and uneven pad deposits. Browse brake pads and brake rotors, or choose a quiet, low-dust set from our ceramic brake pads collection. If you want a higher-friction pad for spirited driving, we carry the EBC Yellowstuff front brake pads (DP41459R) for the Scion xA.

At the same time:

• Replace the anti-squeal shims with the pads. The factory manual says this directly, because worn shims cause noise.
• Clean and inspect the pad support plates and replace them if they are bent, cracked or rusted. A brake hardware kit covers these.
• Clean and regrease the two caliper slide pins with lithium soap base glycol grease, and replace torn boots.
• Check the flexible hoses for cracks or bulges. If you replace brake hoses, use a new gasket on the union bolt.

Rear brake job

Measure the drum inside diameter. If it is over 201.0 mm, replace the drum. The manual also says that if any shoe needs replacing, replace all of them so braking stays even. Rear brake shoes are the main part; with them:

• Replace the wheel cylinder if it is leaking or the bore is rusty or scored. On an older xA it is cheap insurance while the drum is off.
• Replace the return and hold-down springs if they are rusty or stretched. They lose tension with heat cycles.
• Put a thin film of high-temperature grease on the backing plate shoe contact points and the parking brake strut. Keep all grease off the linings and the drum surface.

How hard is the job?

The front pads and rotors are an easy driveway job with basic hand tools: the caliper comes off with two bolts, the bracket with two more, and the rotor slides off the hub. Put matchmarks on the rotor and hub if you are reusing the old rotors. Torque the bracket bolts, caliper bolts and lug nuts to the values in the factory service manual, and pump the pedal before driving so the pistons come back out against the new pads.

The rear drums take more patience. The shoes, springs, adjuster and parking brake strut all have to go back in the right order, and the factory procedure uses special spring tools for the return and hold-down springs. After assembly, the manual's procedure is to expand the adjuster until the drum locks, back it off 8 notches, and then check parking brake lever travel. Take a photo of one side before you start and work on one side at a time, so you always have a reference.

If you open the hydraulic system (a caliper, hose or wheel cylinder), bleed the brakes afterward with fresh DOT 3 fluid, working through each wheel until no air comes out. Our full brake parts catalog covers anything else the job turns up.

Recalls and known problems

The Center for Auto Safety record for the 2005 xA shows no brake-related recalls and no investigations. The recalls on file cover other systems, such as the airbags. For this car, brake wear is normal maintenance, not a known defect. If your car pulls hard, the pedal sinks, or the brake warning light stays on, have it inspected in person rather than just replacing parts.

Frequently Asked Questions

Does the Scion xA have rear disc brakes?

No. North American xA models use front disc brakes and rear drum brakes. The rear shoes also serve as the parking brake.

How often do the rear shoes on an xA need replacing?

Much less often than the front pads. There is no fixed mileage; measure the shoes whenever you do the fronts and replace them before they reach the 1.0 mm minimum, or right away if they are contaminated with fluid.

Can I just replace the front pads and reuse the rotors?

Yes, if the rotors are at least 20.0 mm thick, smooth and within the 0.05 mm runout limit. If they are near the limit, deeply grooved or causing a pulsation, replace them with the pads.

Do xB brake parts fit the xA?

The first-generation xA and xB share the same basic front disc and rear drum brakes, and many parts are listed for both. Always check the fitment on the specific part before ordering.

What brake fluid does the Scion xA use?

The factory manual specifies SAE J1703 / FMVSS No. 116 DOT 3 brake fluid. Do not add DOT 5 silicone fluid to this system.

Sources

1. Scion factory repair manual, front brake inspection - front pad lining 11.0 mm new / 1.0 mm minimum; front disc 22.0 mm standard / 20.0 mm minimum
2. Scion factory repair manual, rear brake - rear drum 200.0 mm standard / 201.0 mm maximum; shoe lining 4.0 mm new / 1.0 mm minimum; replace all shoes together; 8-notch adjuster back-off
3. Scion factory repair manual, front brake installation - 0.05 mm maximum disc runout; shims replaced with pads; matchmarks on disc and hub
4. Scion factory repair manual, brake fluid and bleeding - SAE J1703 / FMVSS No. 116 DOT 3 brake fluid; bleeding procedure
5. Scion 2006 Scheduled Maintenance Guide (2005-2006 xA, xB, tC) - visual brake inspection every 5,000 miles or 6 months; thickness and runout measurement at 30,000-mile services
6. Front rotor specification sheet (2004-2006 xA) - 255 mm vented front rotor, 22 mm nominal / 20 mm discard
7. Center for Auto Safety, 2005 Scion xA record - no brake recalls or investigations on file for the 2005 xA