Brake Fluid

Racing Brake Fluid : Explained

On track your brakes will work a lot harder than regular driving on the street. The accelerating and braking increases the temperature of your brakes and the brake fluid. Brake fade is when the brake pedal goes soft or the pedal goes to the floor combined with loss in braking performance. On track brake fade can happen after a few laps, this will lead to less driver confidence and in worse case scenarios ending up in a gravel track or wall.

How does Brake Fluid Work?

Braking systems on most cars are hydraulically operated. In its most simplistic form, when the driver pushes on the brake pedal, fluid is pushed into the master cylinder, this fluid is then distributed to the brake calipers through the vehicle’s brake lines.

How can brake fluid cause brake fade?

Brake fluid is a hygroscopic liquid, meaning it can absorb water. Over time, brake fluid absorbs water from the atmosphere. In a competitive environment such as a race track, the brake fluid can get hot, this turns any water in the brake lines into gas. Unlike brake fluid, gas can be compressed. This unwanted gas in the brake lines interferes with the fluid delivery into the brake calipers, causing the brake fade “soft pedal” that is experienced on track.

When should I change Brake fluid?

We asked a number of garages, and they recommended changing brake fluid once every two years regardless of usage. We would recommend consulting with your vehicle manual, manufacturer, or car enthusiast community for recommendations.

What does the DOT mean in Brake Fluids?

DOT = Department of Transport; the numbers correspond to standards set by the DOT. The most common grades of brake fluid are DOT 3, DOT 4, and DOT/ 5.1. These types of brake fluids are all glycol-based.

• DOT 3 Dry Boiling Point is 205 °C (401 °F), Wet Boiling Point 140 °C (284 °F)
• DOT 4 Dry Boiling Point is 230 °C (446 °F), Wet Boiling Point 155 °C (311 °F)
• DOT 5 Dry Boiling Point is 260 °C (500 °F), Wet Boiling Point 180 °C (356 °F)
• DOT 5.1 Dry Boiling Point is 270 °C (518 °F), Wet Boiling Point 190 °C (374 °F)

Dry Boiling Point refers to uncontaminated brake fluid which is freshly changed. Wet Boiling Point refers to contaminated brake fluid which has absorbed moisture.

Which brake fluid should I use?

There are a variety of different brake fluids depending on your application. On our track-oriented Nissan Skyline R33 GTR with over 800 brake horsepower, we use A P Racing Radi-Cal R4. This greatly reduced brake fade on tight technical tracks.