Motor Vehicle Brake Fluid Based Upon Glycols, Glycol Ethers and the Corresponding Borates
This SAE Standard covers motor vehicle brake fluids of the nonpetroleum type, based upon glycols, glycol ethers, and borates of glycolethers, and appropriate inhibitors, 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).
1. EPDM (RM69) and SBR (RM03a) are currently tested at 70 °C and 120 °C. 120 °C is more aggressive, and running the test again at 70 °C does not offer any insight to a brake fluid's performance; therefore, testing EPDM and SBR at 70 °C will be discontinued.
2. With respect to EPDM at 120 °C, this test will be suspended until the Committee can decide on a specification adjustment. Testing with the reference fluid (RM66) with EPDM (RM69) yields a volume increase near 0%, and the requirement is currently 0 – 10%. A minimum requirement that has the same value as an average does not fit a best practice philosophy.
3. Testing with the reference fluid (RM66) with EPDM (RM69) on the Metal Corrosion, Wet Corrosion test can yield negative volume swell (<0.5%). The specification of 0 to 10% has been changed to ≤10% as the committee investigates a different EPDM formulation.