ACUSTRIP® Optical Brake Check Under extreme conditions where excessive braking is required rotor temperatures can reach from 500 to 1100° F, easily hot enough to boil brake fluid containing significant water and create an unsafe condition. Introduction As the water content of Brake Fluid increases over time, the boil point decreases. Brake Fluid with reduced boiling point can create vapor by boiling in the wheel cyclinder. This can occur under adverse braking conditions, or with a stuck brake pad. With vapor buildup pressing on the brake pedal applies force to vapor and not the pad. The result may be sudden brake failure. The presence of water in the brake fluid decreases the protection against failure due to brake fluid boiling. Manufacturers recommend regular brake fluid inspections. Over a relatively short period of time brake fluid will absorb moisture from the air. SAE field tests show the average year old car has 2% moisture in the fluid. A random test of vehicles in the U.S. showed an average water content of 2.6% for vehicles with an average age of 8 years. 25% of these vehicles had water content greater than 4% - these vehicles are definite candidates for a brake fluid flush and change. Procedures The BC-3 and BC-4 Brake Check are precision optical tools for determining the boiling point and water content of brake fluid. Checking Brake Fluid with the BC-3 or BC-4 is quick and easy. To test a sample one or two drops of fluid are placed on the sample window. The clear sample cover is lowered into position and the image on the scale is viewed by pointing the instrument toward a light source and focusing the eyepiece. The test takes just a couple of seconds and can be run on samples from the master cylinder or individual wheel cylinders. The BC-3 and BC-4 require no power and are easily cleaned by simply wiping away the small sample. Since this test requires no actual heating of the sample it can be performed on consecutive samples without waiting for the instrument to cool. Use the BC-3 or BC-4 regularly to control the following problems: The boiling point decreases - Fluid with a reduced boiling point can create a vapor by boiling in the wheel cylinder. Normally this could happen under adverse conditions such as braking down a long steep grade or with stuck brake pads. Under these conditions rotor temperatures can climb high enough to boil brake fluid with high water content. Stepping on the brake pedal will now only compress the vapor instead of applying force to the pad. The result is sudden brake failure. DOT 3 Fluid with no moisture content boils at greater than 401° 'F (205° C) as specified by DOT Standard 116. The fluid in a 3 to 4 year old car with 3 to 4% moisture content could boil at less than 300° F (149° C). The viscosity increases - Brake Fluid must flow freely to be effective. In extremely cold weather brake fluid water content is very viscous, causing slow pedal response and requiring more effort. Corrosion problems can occur -Water in brake fluid can contribute to the corrosion of parts such as the steel pistons and ABS modulators. Specifics BC-3 DOT 3 Brake Fluid Tester: Includes scales for Standard DOT 3 and High Temperature DOT 3 Brake fluids for Fords and Racing brake fluids. BC-4 DOT 4 Brake Fluid Tester: Includes scales for Standard DOT 4 and DOT 4 Plus (Super). Boiling point and water content are read where the dark and light areas meet on the scale. Specifications are subject to change without notice. We reserve the right to correct errors without warranty or obligation. All trademarks are the property of their respective owners. Copyright © - 2003, Acustrip and EB Communications