Attached

This NPRM makes changes to the safety standard specifying requirements for brake fluids used in hydraulic brake systems for motor vehicles. It makes necessary updates to industry standards but, more importantly, updates the standards to address the growing use of a different type of rubber for brake seals. In addition to the styrene butadiene rubber (SBR) currently addressed in the standard the proposed change will incorporate requirements to address the growing use of ethylene, propylene, and diene terpolymer (EPDM) rubber in the manufacture of various brake seals. I appreciate the importance of updating referenced industry standards. However, my comments focus on the changes regarding the impact of EPDM rubber components in the standard. My observations are in two broad areas: (1) The requirements and test procedures addressing the EPDM components rely much more heavily on reference to Society of Automotive Engineers (SAE) standards than do the specifications addressing the SBR components. (2) Two of the requirements address SBR without modification for including the effects of EPDM.