GMW GMW8518 PDF

Note: Nothing in the specification supersedes applicable laws and regulations unless specific exemption has been obtained.

Note: In the event of conflict between the English and domestic language, the English language shall take precedence.

Purpose.

To implement a worldwide uniform process for evaluating the Squeak and Rattle (S&R) performance of a complete vehicle. This includes the detection, the evaluation (by subjective rating of S&R complaints), as well as some root source analysis. Furthermore the documentation of S&R complaints and the results of the root source analysis are described for initiation of problem resolution. This procedure consists of three parts: A Quasi-static Evaluation, a Dynamic Road Simulation Evaluation (where available) and a Dynamic On-road Evaluation.

This procedure also provides detailed instructions for temperature evaluations using environmental road simulator.

Forward.

This procedure will guide an evaluator through full vehicle Squeak and Rattle Evaluations.

The General Motors Uniform Test Standard (GMUTS) Subjective Rating Scale with the performance and disturbance critera is used to evaluate components and subsystem.

Applicability.

For all passenger cars, light commercial vehicles and medium duty trucks.

Definitions.

S&R -Noise:

Disturbing or annoying noises excited by dynamic or static inputs, as well as noises which occur while operating vehicle components. This means all noises which are avoidable and which customers do not expect.

Root Source:

Often confused with Root Cause, Root Source pertains to identifying where the noise source is (i.e., the exact location on each of the two parts that came incontact to produce the S&R). Root source clues include witness marks, wear, fastener loosening, broken or mis-installed integral fasteners and/or clips. Root Cause Analysis goes a step further, often requiring one to look at the Engineering Drawings, Tolerances, actual parts and perhaps the manufacturing and/or assembly process to determine why the noise is occurring. The reasons why may include that the parts are in not built to specification and that the design, manufacture and assembly processes are not capable of producing S&R free parts.

Quasi-Static:

Customer actuated component and subsystem movement, operation and/or adjustment when the vehicle itself is stationary.

Typical Force:

The normal or average force required to operate an adjustment, accessory or feature of a component or sub-system.

Mode of Operation:

The directional movement of a component that is evaluated. For example: The power exterior mirror has (4) modes of operation: up, down, inboard and outboard.