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.

Purpose

This recommended test practice is intended to establish a common universally recognized method for performing a series of screening test sequences that identify the propensity of a brake assembly to generate squeal noise under a variety of test conditions. The result is an evaluation of the brake propensity to generate brake noise under a set of defined braking conditions that are believed most relevant to braking system development for automobiles.

A disc brake application matrix and drum brake application matrix are defined to describe the test conditions and steps to investigate the influence of pressure, temperature and velocity on squeal noise behavior. Each matrix is intended to replicate vehicle tests to get a fair comparison for different brake corner components.

Rationale

This procedure has been revised to address to fundamental limitations of the previous version. Drum brake testing was not dealt with in the previous version. Part B of this revised procedure provides a detailed test specification for the evaluation of drum brake noise. This new section was specifically designed and validated for drum brakes.

Another issue was low temperature squeal of disc brakes. The previous procedure did not address this issue. Since the initial release of the procedure, vehicle manufactures have required suppliers to provide cold noise data using a modified version of SAE J2521. The revised disc brake procedure incorporates a cold section for brake noise analysis that satisfies this requirement and provides a practical evaluation procedure.

 

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