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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.

This document defines various vehicular noises and vibrations that are attributed to being created by the foundation brake components of the vehicle, particularly on passenger cars and light trucks. These definitions cover both disc and drum brakes. The frequency ranges from near zero Hz (tactile sensations) all the way up to 17 kHz, or the upper limit of normal hearing. These noises and vibrations may either directly radiate off the brake system or provide the excitation energy that causes other vehicle components to react.

The SAE J2521 procedure is applicable to high frequency squeal noise occurrences for on-road passenger car and light trucks below 4,540 kg of GVWR. The procedure incorporates high temperature and low temperature test matrixes, but does not fully account for the effects of the environment on brake squeal. Much research is currently underway in this area and can potentially be incorporated in future revisions. For the purposes of this test procedure, squeal is defined as peak noise levels equal to or above 70 dB(A) between 1.25 kHz and 16 kHz for tests using a full suspension corners or full axle assemblies, or between 2 kHz and 16 kHz for brakes not using a full suspension corner.

This document defines various vehicular noises and vibrations that are attributed to being created by the foundation brake components of the vehicle, particularly on passenger cars and light trucks. These definitions cover both disc and drum brakes. The frequency ranges from near zero Hz (tactile sensations) all the way up to 17 kHz, or the upper limit of normal hearing. These noises and vibrations may either directly radiate off the brake system or provide the excitation energy that causes other vehicle components to react.

The SAEJ2521 procedure is applicable to high frequency squeal type noise occurrences for passenger car and light truck type vehicles that are used under conventional operating conditions. The procedure incorporates high temperature and low temperature test matrices, but does not fully account for the effects of the environment on brake squeal. Much research is currently underway in this area and can potentially be incorporated in future revisions. SAEJ2521 procedure is applicable to high frequency squeal type noise occurrences for passenger car and light truck type vehicles that are used under conventional operating conditions. For the purposes of this test procedure, squeal is defined as occurring between 900 and 17,000 Hz for disc brake tests utilizing a full suspension corner assembly, between 2000 and 17,000 Hz for disc brakes not utilizing a full suspension corner assembly and between 500 and 17,000 Hz for drum brakes.