Low-preload Deflection Measurement for Brake Pads, Noise Shims, and Brake Pad Assemblies
This SAE Standard specifies a method for measuring the deflection of friction materials, noise insulators, and disc brake pad assemblies to be used in road vehicles with a Gross Vehicle Weight Rating below 4336 kg.
This part of the SAE J3079 includes the test for deflection and creep at various pressures under ambient temperature conditions.
This SAE test method differs from SAE J2468 and ISO 6310 in the preload and maximum load applied to the test sample when deflection is measured. It also introduces additional measurements such as for deflection offset, hysteresis, and creep.
This standard addresses brake pad deflection characteristics similar to SAE J2468 with the following refinements:
The brake system pressure range is from 30 kPa to 13000 kPa
Test results are summarized both graphically and in tabular format
Includes guidelines to improve the accuracy and repeatability
Includes a description of a test procedure for noise insulators
The deflection characteristics of friction materials, noise insulators, and disc brake pad assemblies are commonly used in caliper and brake system design as well as for quality control during manufacturing. Pad deflection influences many design characteristics including brake fluid consumption, caliper stiffness and mass, caliper piston retraction, and park brake adjustment. The deflection also influences performance characteristics including brake pedal travel, brake drag, park brake performance, and the propensity of the brake system to generate noise and roughness.