SAE J2625:2017 pdf free

SAE J2625:2017 pdf free.Automotive Vehicle Brake Squeal Test Recommend Practice
Occurrence (absolute) is the percentage of the total brake applications where the peak interior sound level exceeded the threshold of 50 dB(A). It is calculated by dividing the number of brake applications with a sound level above the threshold by the total number of brake applications in the test. In a specific case, the user can define an alternative threshold, which must be documented.
Relative occurrence is the number of the stops in a particular test section where the peak interior sound level exceeded the threshold of 50 dB(A) divided by all of the brake applications where the sound level exceeded the threshold – expressed as a percentage.
This matrix describes the test conditions and steps to investigate the influence of pressure, temperature and velocity on the squeal noise performance of brakes. This matrix is intended to provide a basic vehicle test to obtain a fair comparison for different brake corner sets of components across an axle. Should special conditions such as noise tests adjacent to a wall be used, this shall be noted in the test report.
Throughout this test the specified temperature is to be determined at either the left or right front wheel position exhibiting the highest temperature. The position of the governing temperature measurement shall be recorded for all tests. This is the preferred measurement procedure. As an option, one may specify the critical temperature location that will be the governing temperature for all measurements. This location shall be recorded.
The preferred accelerometers location for disc brakes is at the rear of the leading piston. This provides a well-defined location with generally free access for mounting. If one is stud mounting the accelerometer, care should be taken to avoid drilling too deeply and causing a brake fluid leakage problem. In the event of difficulty in mounting the accelerometer at this location an alternative location can be used. This new location shall be noted.
For drum brakes, the accelerometer shall be mounted on the backing plate at a point where there is clearance and a flat surface for rigid mounting. The accelerometer shall be oriented in a lateral direction to vehicle motion. The location of the accelerometer shall be noted.SAE J2625 pdf free download.