Motor Vehicle Brake Fluid

This SAE Standard covers motor vehicle brake fluids of the nonpetroleum type for use in the braking system of any motor vehicle such as a passenger car, truck, bus, or trailer. These fluids are not intended for use under arctic conditions. These fluids are designed for use in braking systems fitted with rubber cups and seals made from styrene-butadiene rubber (SBR), or a terpolymer of ethylene, propylene, and a diene (EPDM).

References to RM materials: From January 1, 2007 onwards, SAE International has discontinued the supply of referee materials (RM). Equivalent materials to the RM materials referred to in this standard are obtainable from sources other than SAE International. References to SAE International providing such RMs are removed from this standard. RM designations/numbers have been left in tact in this standard for reference purposes. Stroking test: The stroking test was withdrawn for a period of 3 years to allow time for development of a test method that would represent current components. This goal has not yet been accomplished and the committee decided to extend this time for another 3 years to achieve this objective. The stroking test was originally developed to evaluate the lubrication- and rubber swell quality of brake fluids. The present test includes components that have been out of OEM production for over 35 years. The hardware sources used for the stroking test are Aftermarket. It is getting difficult to obtain such parts, as they are practically obsolete. The set up of the test has no relationship to a modern braking system and provides limited information on how a brake fluid behaves in a field situation. Using the present set up utilizing a single master cylinder with SBR vs. EPDM, totally different seal constructions and a single system, does not provide viable test results related to current systems, e.g. dual systems required by NHTSA and used since the 60's. The stroking test no longer reflects current technology and therefore the committee members voted to cancel the stroking test. However, since this excludes a way to evaluate brake fluids for lubricity. This is an important performance parameter and there is a clear need for the development of a new method in line with the present brake practice. A recommendation for a test that will provide the testing of current components and materials is needed. A replacement test must be developed as a high priority. This new test should reflect the design practice and material trends in brake systems that specify the fluid.