Brakes

When Do Brake Pads Need Replacing? A Mechanic Explains

14 May 2026 · Hitech Auto Mechanical

Brake pads are a wear item. They are designed to wear out, and replacing them is routine maintenance rather than a repair. The difficulty is that the wear happens so gradually that most drivers never notice their braking performance dropping — right up until something makes a noise.

Here is how to tell where you actually stand.

The wear indicator squeal

Most brake pads have a small metal tab built into them called a wear indicator. When the friction material wears down to roughly 3mm, that tab starts contacting the disc and produces a high-pitched squeal, usually loudest when braking gently at low speed.

That squeal is the pads doing exactly what they were designed to do: telling you they are near the end of their life. It is not an emergency, but it is a booking rather than a “next time I think about it”.

Grinding is different

A deep metallic grinding sound is not the wear indicator. It means the friction material is gone entirely and the metal backing plate is now pressing directly against the disc.

At that point you are no longer just replacing pads. Every kilometre driven is cutting grooves into the disc, and what would have been a straightforward pad replacement becomes pads and discs. If your brakes are grinding, stop driving the car any more than you have to.

What actually determines pad life

There is no fixed interval, and anyone who quotes you one without knowing your car is guessing. Front pads commonly last somewhere between 30,000km and 70,000km, but the spread is enormous because it depends on:

Where you drive. Stop-start city traffic wears pads several times faster than highway kilometres. Inner-Sydney driving is about as hard on brakes as it gets.
How you drive. Late, hard braking wears pads considerably faster than reading the road ahead and coasting.
What you drive. Heavier vehicles, and cars that tow, put far more energy through the brakes.
Pad material. Cheaper pads wear faster and often dust more.

Because of that spread, measuring is the only reliable approach. We check pad thickness at every service and tell you the actual reading, so you get warning well ahead of time.

Symptoms worth acting on

Beyond noise, these all point at the braking system:

The pedal feels soft, spongy, or travels further than it used to
The car pulls to one side under braking
The steering wheel or brake pedal vibrates when you slow down
The brake or ABS warning light is on
You can see through the wheel that the pad material looks very thin

A pulsing pedal usually means disc thickness variation rather than pad wear. Pulling to one side often means a sticking caliper slide pin, which is inexpensive to fix but will chew through one side’s pads if ignored.

Do the discs need replacing as well?

Often, no — and this is where a lot of money gets spent unnecessarily.

Brake discs have a minimum thickness stamped or cast into them by the manufacturer. As long as the disc is above that figure, is not badly scored, and has acceptable run-out, it can frequently be reused or machined rather than replaced.

We measure discs with a micrometer and show you the readings against the manufacturer minimum. Sometimes they genuinely do need replacing — a disc below minimum thickness cannot dissipate heat properly and is not safe to keep. But “we always do discs with pads” is a policy, not a diagnosis.

The part people forget: brake fluid

Brake fluid is hygroscopic, meaning it absorbs moisture out of the air over time. Water in the fluid lowers its boiling point, and fluid that boils under sustained heavy braking produces vapour in the lines — which compresses, unlike liquid. The result is a pedal that sinks toward the floor exactly when you need it most.

Fluid degrades on a calendar, not an odometer, so a low-kilometre car is not exempt. Most manufacturers specify replacement every two years. We test moisture content at every service.

What we do

At every service we measure pad thickness, measure disc thickness and run-out, test brake fluid moisture content, and check the caliper slides and hoses. That inspection is included — you should not have to pay to find out whether your brakes are safe.

If something needs doing we will tell you what, why, and what happens if you leave it. If it does not, we will tell you that too.

Brakes are the one system where “probably fine” is not good enough. If yours are making a noise, or the pedal does not feel like it used to, call us on 02 9667 4008 or book a service and we will take a proper look.