Keep in mind, glycol-based fluids cannot only damage paint, they are also toxic. Any brake bleeding operation should include a small-diameter hose attached to the bleeder on one end and a collection container on the other. All of the purged fluid should be captured and properly disposed of, just like you would with used engine oil.

It should be pointed out that not all DOT 3, DOT 4, and DOT 5.1 compliant are the same. Although they will share the same minimum wet boiling point required by DOT, they can be formulated to begin life at a much higher dry boiling point. Dry boiling point pertains to new fluid that has not yet been able to absorb water vapor out of the atmosphere. Wet boiling occurs when fluid has reached maximum water saturation after. Performance grade and racing grade fluids such as Wilwood’s DOT 3–compliant Hi-Temp 570 and DOT 4–compliant EXP 600 Plus Super Hi-Temp fluids are formulated to have much higher boiling points.

Racers who maintain regular bleeding and maintenance cycles on their fluids have the best opportunity to prevent heat-induced brake pedal fade by keeping the fluid in the system fresh and at the highest possible boiling point. Fluid that has deteriorated to its wet boiling point will boil and

fade far sooner in the heat of competition.

For high-performance applications, fluids such as Wilwood’s EXP 600 Plus have a higher specific gravity and lower viscosity than standard DOT 3 or 4 compatible fluids. Race fortified fluids will be far less compressible in high-heat conditions, and maintain a firmer, more consistent feel in sustained high-heat conditions.

When adding fresh fluid to a brake system never mix fluids of DOT classifications as it will cause contamination and lower the boiling point. For maximum performance, start with the highest Dry Boiling Point available, flush the system completely, and flush it regularly, especially after severe temperatures have been experienced.

Advice on Bleeding Brakes from Wilwood

When replacing a master cylinder, always bench bleed it first and then the system.

Before beginning to bleed the system, make sure all calipers have bleed screws facing upward to fully evacuate air from the system. Wilwood calipers with internal fluid passages and four bleed screws (two on each end) require only the upward facing bleed screws to be bled. Start bleeding the bleed screw farthest from the master cylinder (typically the right rear caliper outboard half), and work toward the one nearest the master cylinder.

The most common method to bleed a system is to manually pump the pedal. This process is as follows: Pedal bleeding requires two people; one person pumps the pedal, and the other operates the bleed valves. First, connect a plastic hose to the valve on the outboard body bleed screw farthest away from the master cylinder. Submerge the other end of the hose in a container of brake fluid to ensure that no air is siphoned back into the system. Have the person in the vehicle depress the pedal and hold it at the floor. With the pedal on the floor, the person at the caliper should open the bleed screw a quarter of a turn to allow the accumulated air and fluid to evacuate. Once the air and fluid have

stopped flowing out of the bleeder valve, close it. Now, the person in the vehicle should slowly pump the pedal to refill the calipers with fluid.

Once a firm pedal has been achieved, the pedal operator should depress the pedal and hold it, repeating the above sequence. Make sure that the reservoir of the master cylinder does not run out of fluid, as this will introduce air into the system. Continue in this manner until all calipers are bled on both the inboard and outboard bleed screw. You may have to repeat the process for optimal results. Three other methods to bleed a system are gravity, pressure, and vacuum.

Gravity bleeding can be done when the master cylinder is higher than the wheel cylinders. It’s simply a matter of cracking the bleeders open and letting fluid drain until all the air is removed. It’s effective but a very slow process.