What Is Brake Fade?
Brake fade is a reduction in braking effectiveness caused by overheating. It usually occurs on long downhill descents when brakes are applied repeatedly or held on continuously. The pedal may feel normal, but the car slows much less than expected — an alarming experience on New Zealand's hilly terrain.
Why It Happens
Brakes work by converting kinetic energy into heat through friction. On a brief stop, that heat is manageable. On a long descent — like many of New Zealand's alpine or hilly roads — continuous braking can push temperatures well beyond what the brake components are designed to handle.
Pad fade: The friction compound in the brake pad reaches a temperature where it becomes less effective. At very high temperatures, the pad material can actually gasify slightly, creating a thin layer of gas between the pad and rotor — reducing friction dramatically.
Fluid fade (vapour lock): If brake fluid boils, the resulting vapour (which is compressible) replaces incompressible fluid in the lines. The pedal goes soft or all the way to the floor. This is the more dangerous form of fade.
When Is It Most Likely?
- Long descents in hilly or mountainous areas (the Rimutakas, the Brynderwyns, the Kaimai Ranges)
- Towing a heavy trailer
- Driving a heavily loaded vehicle
- Using low-quality or contaminated brake fluid
How to Manage Brake Temperature on Downhills
The key is engine braking. Before a long descent:
- Shift into a lower gear (manual) or use the L/engine braking mode (automatic)
- Let engine braking do the bulk of the work
- Apply brakes briefly and firmly rather than riding them continuously
Brief, firm applications heat the brakes momentarily but allow cooling between applications. Continuous light pressure keeps them hot constantly.
What to Do If Fade Happens
- Immediately use engine braking — downshift
- Pump the brakes to try to restore some pressure
- Find a safe place to pull over and allow brakes to cool (at least 10–15 minutes)
- Do not use the handbrake as a primary stop while moving at speed
Prevention
- Service brake fluid regularly (contaminated fluid has a lower boiling point)
- Check pad thickness before long trips — worn pads generate more heat
- Upgrade to higher-performance brake fluid or pads if you regularly do hilly driving or towing