What Is a Brake Caliper?
The brake caliper is the hydraulic clamp that sits over your brake rotor. When you press the brake pedal, pressurised brake fluid from the master cylinder pushes a piston (or multiple pistons) inside the caliper outward, squeezing the brake pads against both faces of the spinning rotor and slowing your car.
When you release the pedal, fluid pressure drops, the piston retracts slightly, and the pads pull back from the rotor surface so the wheel can spin freely.
Types of Brake Calipers
| Type | How It Works | Common Use |
|---|---|---|
| Floating (sliding) caliper | One or two pistons on the inboard side; the caliper body slides on guide pins to apply the outer pad | Most modern NZ passenger cars |
| Fixed caliper | Pistons on both sides of the rotor; no sliding action | Performance vehicles, some SUVs |
Floating calipers are simpler and cheaper to manufacture, which is why you'll find them on a Suzuki Swift or Toyota Corolla. Fixed calipers offer more consistent feel and are found on vehicles where braking performance is prioritised.
How Do Calipers Fail?
1. Seized Piston
Over time — especially in NZ's coastal environments where salt air accelerates corrosion — the rubber seals around the caliper piston can harden, crack, or tear. When this happens, the piston no longer retracts fully after braking. The pad stays in light contact with the rotor permanently, generating:
- Constant drag and heat on that corner
- Accelerated pad and rotor wear (sometimes destroying a rotor in weeks)
- Reduced fuel economy from the extra resistance
- A strong burning smell after driving, especially after hills
2. Seized Slide Pins (Floating Calipers)
The guide pins that allow a floating caliper to slide must be kept clean and lubricated. If the rubber boots tear, pins corrode and seize. A seized pin means only one pad contacts the rotor, causing:
- Uneven pad wear — inner pad wears rapidly, outer pad barely touches
- Pulling to one side under braking
- Noise — grinding or squealing from the unevenly loaded pad
3. Brake Fluid Leak
A cracked or perished caliper seal can allow brake fluid to weep out. You may notice:
- Wet residue around the back of the wheel
- Soft or low brake pedal as fluid level drops
- Reduced braking force on that corner
A brake fluid leak is a safety emergency — do not drive the vehicle.
What Does a Seized Caliper Do to Your Car?
A fully seized caliper turns a simple brake service into a much larger repair. The constant friction:
- Overheats the rotor, potentially warping or cracking it
- Transfers heat to the wheel bearing, accelerating bearing wear
- In severe cases, can ignite accumulated road dust or brake dust, causing a wheel fire
A seized caliper will also fail a WoF inspection. The inspector checks that brakes apply and release correctly and that there is no uneven drag.
How Much Does a Brake Caliper Replacement Cost in NZ?
| Service | Estimated NZD Cost |
|---|---|
| Single caliper (remanufactured, parts + labour) | $250–$450 |
| Single caliper (new OEM or aftermarket) | $350–$600+ |
| Caliper rebuild kit (seals + dust boots) | $80–$180 labour + parts |
| Slide pin service (clean + re-grease) | $60–$120 per axle |
Caliper prices vary significantly by vehicle. European cars and four-wheel-drive utes tend to cost more. Remanufactured calipers from reputable suppliers (e.g., Protex, RDA) are cost-effective and carry a warranty.
When to Book a Mechanic
Book promptly if you notice:
- The car pulling to one side when braking
- A burning smell after normal driving
- One wheel noticeably hotter than the others after a drive
- Grinding or constant noise from one corner
- Any sign of brake fluid leaking from behind a wheel
Do not delay a brake fluid leak — low fluid can lead to brake failure.