Brakes are the single most important safety system on your vehicle. Understanding the difference between pad wear and disc wear — and knowing when each needs attention — helps you maintain your brakes correctly and avoid overpaying for unnecessary replacements.
How Disc Brakes Work
Disc brake systems use a caliper to squeeze brake pads against a spinning metal disc (rotor) to slow the vehicle. The pads are the sacrificial wear component — designed to wear out and be replaced relatively cheaply. The discs are thicker and designed to last longer, but do wear and can also warp from heat cycling.
When Do Brake Pads Need Replacing?
Brake pads need replacing when:
- The pad thickness reaches 2–3mm (minimum safe thickness) — usually indicated by a wear indicator that creates a squealing sound
- You hear persistent squealing during normal braking (not just cold weather)
- You hear grinding metal-on-metal contact — pads are completely worn through
- Visual inspection shows thin pads through the wheel spokes
When Do Brake Discs Need Replacing?
Brake discs need replacing or machining when:
- Disc thickness is below the manufacturer's minimum specification
- Deep grooves are scored into the disc surface from worn-through pads
- Significant warping causes pulsation through the pedal under braking
- Significant rust pitting that can't be machined out
Do You Always Replace Both Together?
Not necessarily — but it depends on the condition of each. If pads are worn but discs are within specification and free of scoring, replacing pads only is appropriate. If discs are scored or below minimum thickness, they must be replaced or machined — and new pads should always go on with machined or new discs. Running new pads on worn discs compromises performance and accelerates the new pads' wear.
Typical Brake Costs in Perth
- Brake pad replacement (front or rear): $180–$350
- Brake disc machining (per axle): $120–$200
- Brake disc replacement (per axle, budget pads): $280–$500
- Full brake job (all four corners, quality parts): $600–$1,200
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