By Core Brake Parts Tech Team — Circleville, OH warehouse
On a 2011-2015 Scion iQ, the front brakes wear out first, usually by a wide margin. The iQ uses disc brakes up front and drum brakes in the rear, and the front discs do most of the stopping work, so plan on replacing front pads (and often rotors) several times before the rear shoes need attention. The rear drums still need periodic inspection and adjustment, because they carry the parking brake and can hide problems a quick glance will not show.
How the Scion iQ Brake System Is Laid Out
The iQ is a tiny car, about 120 inches long according to Toyota, with a curb weight of roughly 2,127 lbs and a 1.3-liter four-cylinder making 94 horsepower. Toyota fitted it with a mixed brake layout that is common on small, light cars:
- Front: disc brakes, with a caliper squeezing pads against a rotor at each front wheel.
- Rear: drum brakes, with two curved shoes pushed outward by a wheel cylinder against the inside of a cast drum. Toyota's genuine rear drum for the iQ is listed as part number 42431-74010.
- Electronics: every iQ came with Toyota's Star Safety System, which includes anti-lock brakes (ABS), Electronic Brake-force Distribution (EBD), Brake Assist, Traction Control, Vehicle Stability Control and Smart Stop brake-override.
The parking brake on the iQ works through the rear drum shoes, so the rear brakes do two jobs: help stop the car and hold it when parked. Tires are P175/60R16 on all four corners, which matters when you are judging whether a pull or vibration is a brake problem or a tire problem.
Why the Front Brakes Wear First
When any car brakes, its weight shifts forward. The nose dips, the front tires press harder into the road and the rear tires get lighter. The front tires can therefore put more braking force into the pavement without locking, so the system is designed to send most of the braking effort to the front. On the iQ, EBD fine-tunes that split in real time so the rear wheels do not lock up when the back of the car is light.
The result is that the front pads convert most of the car's speed into heat and wear accordingly. The iQ also has a very short wheelbase and short overhangs, which makes weight transfer under braking abrupt. City driving, where the iQ spends most of its life, means frequent stops and more front pad wear per mile than highway driving.
The rear drum shoes see a smaller share of the braking load and have a large friction area for that load, so it is normal for them to outlast several sets of front pads. That is not a reason to ignore them, though.
Symptoms: Is It the Front or the Rear?
| Symptom | Most likely end | What it usually means |
|---|---|---|
| High-pitched squeal that stops when you press the pedal | Front | Pad wear indicator touching the rotor; pads are near the end |
| Grinding or scraping when braking | Front (most often) | Pad friction material gone, steel backing on the rotor; rotors now damaged |
| Steering wheel shake while braking | Front | Uneven rotor thickness or pad deposits on the rotor |
| Pedal pulsation felt in the seat, not the wheel | Rear | Out-of-round drum |
| Parking brake lever pulls up higher than it used to | Rear | Worn shoes or self-adjusters not working |
| Low pedal that improves after pumping | Rear or hydraulic | Shoes out of adjustment, or air in the lines |
| Wet inside of a rear tire or backing plate | Rear | Leaking wheel cylinder; replace before it soaks the shoes |
A pull to one side under braking can come from either end: a sticking front caliper slide pin, a contaminated rear shoe, or simply mismatched tire pressures. Check tire pressures first, then look at the brakes.
Replacing the Front Brakes
A front brake job on the iQ is straightforward. With the wheel off, the caliper unbolts from its bracket, the old pads come out, and the rotor slides off the hub once the bracket is removed. What to replace:
- Pads: always replace both front wheels together. For daily driving, a ceramic compound keeps dust and noise down; browse ceramic brake pads or the full brake pads collection.
- Performance option: we carry the EBC Yellowstuff front brake pads for the 2011-2015 Scion iQ 1.3L. EBC describes Yellowstuff as an aramid-fiber compound with strong bite from cold and a green fade threshold of 400 C (750 F). EBC also states plainly that these are not low-dust pads, so expect dirtier wheels in exchange for the extra bite.
- Rotors: replace or machine them if they are below the minimum thickness stamped on the rotor, scored from metal-to-metal contact, or causing a shake. See brake rotors.
- Hardware: new abutment clips and freshly lubricated slide pins prevent the uneven pad wear that shortens a brake job's life. A brake hardware kit covers the clips.
Torque the caliper bracket bolts, caliper bolts and lug nuts to the values in the factory service manual, then bed the new pads with a series of moderate stops before any hard braking.
Servicing the Rear Drum Brakes
Rear drum service takes more patience than a front pad job, mainly because of the springs and the self-adjuster. Pull the drum (backing off the adjuster first if a lip has worn into it), then inspect:
- Shoe lining: replace when it is worn to the service limit in the factory manual, cracked, or soaked with fluid or grease. Replace both rear wheels together. Shop brake shoes.
- Drum: check the inside diameter against the maximum stamped on the drum, and look for scoring, a hard lip or heat spots. Toyota's own guidance is to inspect drums for surface wear or contamination whenever shoes are replaced.
- Wheel cylinder: peel back the dust boots. Any fluid behind them means the cylinder is leaking and should be replaced now.
- Springs and adjuster: a hardware kit restores spring tension; clean and free up the adjuster so it keeps the shoes close to the drum.
After reassembly, adjust the shoes so the drum turns with light drag, then check parking brake travel. A correct rear adjustment firms up the pedal and keeps the parking brake holding on a hill.
What to Replace at the Same Time
- Brake fluid: fluid absorbs moisture over time, which lowers its boiling point and corrodes the wheel cylinders. Use the DOT specification printed on the master cylinder cap and in your owner's manual, and flush on the schedule Toyota lists.
- Brake hoses: a cracked or swollen front hose can cause a soft pedal or a pull. Inspect them any time the wheels are off; see brake hoses.
- Calipers: a front caliper that hangs up wears one pad faster than the other and overheats the rotor. Rebuilt units are in our brake calipers collection.
Recalls and How Hard the Job Is
NHTSA's recall database lists a 2012-2013 iQ recall (campaign 12V528000) for the Occupant Classification System cable under the passenger seat, which affects airbag behavior. It is not a brake recall, and we found no brake-system recall for the iQ, but it is worth running your VIN at nhtsa.gov to confirm the airbag work was completed.
For difficulty: front pads and rotors are a good first brake job for a home mechanic with a jack, stands and a torque wrench. Rear drum shoes are intermediate; take a photo of the spring layout before you disassemble and do one side at a time so you always have a reference. If the pedal is low or spongy after the job, the system likely needs bleeding, and an ABS-equipped car like the iQ is best bled following the factory procedure.
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Shop Brake Pads & Kits →Frequently Asked Questions
Does the Scion iQ have rear disc brakes?
No. US-market 2011-2015 Scion iQ models use front disc brakes and rear drum brakes. The parking brake operates through the rear drum shoes.
Should I replace the front and rear brakes at the same time?
Not necessarily. The fronts wear much faster, so most iQs need front pads several times before the rear shoes are due. Replace each axle when it is worn, but inspect the rears every time you do the fronts.
Do I need new rotors every time I replace the front pads?
Only if the rotors are below minimum thickness, deeply scored or causing vibration. Measure them before deciding; rotors that are in good shape can be reused with new pads.
Why does my parking brake handle pull up so high?
Usually the rear shoes are worn or the self-adjusters have stopped working, so the shoes sit too far from the drums. Adjusting the rear brakes, or replacing the shoes and hardware, normally cures it.
Are performance pads worth it on a Scion iQ?
For most commuting, a quality ceramic pad is the best fit. A performance pad such as EBC Yellowstuff adds cold bite and fade resistance for spirited driving, at the cost of more brake dust.
Sources
- CarSpecs: 2012 Scion iQ specifications - front disc and rear drum brakes, 4-wheel ABS, P175/60R16 tires, 2,127 lb curb weight
- Toyota Newsroom: 2012 Scion iQ - Star Safety System contents, 1.3L 94 hp engine, 120.1-inch length
- NHTSA recall data: 2012 Scion iQ - campaign 12V528000, Occupant Classification System cable
- Toyota Genuine Parts: rear brake drum 42431-74010 - rear drum part and inspection guidance
- EBC Brakes: Yellowstuff pads - aramid compound, cold bite, 400 C green fade threshold, not low-dust
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