Brake fade
Brake fade is a loss of stopping power from overheated brakes, felt as a pedal that goes hard and ineffective or long and soft.
Also called: pad fade, fluid fade, boiled brakes
Brakes turn speed into heat, and track driving makes a lot of it. Pad fade happens when the pad material gets hotter than its working range: the pedal feels firm, but the car simply does not slow as it should, and you may smell hot pads. Fluid fade happens when the brake fluid boils and forms vapor bubbles, which compress; the pedal sinks long and soft, sometimes nearly to the floor.
The fixes are different. Pad fade calls for a pad compound rated for track temperatures and better cooling. Fluid fade calls for fresh, high-boiling-point fluid, because fluid absorbs moisture over time and its boiling point drops. Many track drivers bleed their brakes before every event for exactly this reason.
If the pedal changes on track, back off immediately. Brake earlier and gentler, take a slow lap with as little braking as possible, signal, and come into the pits. Do not drag the brakes or hold them hard at a standstill when they are this hot.
Fade removes the one system you rely on most at the end of a straight; recognizing it early is a key safety skill.