Disc and Drum Brake Dynamometer Low-Frequency Noise Test Procedure
This test procedure outlines the necessary test equipment (test fixture, dynamometer, data acquisition system, etc.) and test sequence required to test for low-frequency brake noise (200 Hz to 1.25 kHz) on a brake noise dynamometer. It is intended to complement SAE J2521, which focuses on high-frequency brake squeal. This RP applies to passenger cars and light trucks with a gross vehicle weight rating below 4536 kg. Before using this RP for heavier vehicles, consult and agree with the test requestor and the testing facility.
The development of this SAE Recommended Practice (RP) was based on a vehicle with known low-frequency noise from field and chassis dynamometer testing. The main test sequence reflected on this RP was able to reproduce on an inertia dynamometer the dominant frequencies measured on the vehicle. During the development of this RP, fixture design and fingerprinting for frequency response, along with the actual test sequence and the data analysis, proved to be the three main elements to allow the measurement and detection of noisy brake events below 1 kHz.