WORLDWIDE
ENGINEERING
STANDARDS
Test Procedure
Noise and Vibration
GMW14762
Powertrain Mounting Rigid Body Modes Evaluation Procedure
© Copyright 2005 General Motors Corporation All Rights Reserved
December 2005
Originating Department: North American Engineering Standards
Page 1 of 3
1 Scope
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.
1.1 Purpose. The purpose of this test procedure is
to determine the in-vehicle rigid body natural
frequencies and corresponding mode shapes of a
powertrain in the 0 to 40 Hz frequency range.
1.2 Foreword. Data from in-vehicle powertrain
rigid body modal surveys is often used as a means
of describing the performance of GM and
competitive powertrain mounting systems.
This test procedure shall be followed in its entirety
with the exception of those deviations listed in the
Regional Appendices (To Be Developed).
1.3 Applicability. This test procedure is
appropriate for benchmarking competitive and GM
passenger vehicles in the full vehicle state. This
procedure is valid for use with both Body Frame
Integral and Body on Frame full vehicles.
The testing standards defined in this document are
intended to pertain only to work being done for the
corporate database and validation. Other testing
methods and interpretations are useful and valid,
and should continue to be used for normal
powertrain mounting system development work
where appropriate.
2 References
Note: Only the latest approved standards are
applicable unless otherwise specified.
2.1 External Standards/Specifications.
None
2.2 GM Standards/Specifications.
GMW8477 GMW14229
GMW14172
3 Resources
3.1 Facilities. Reference GMW8477.
3.2 Equipment. Reference GMW8477.
3.3 Test Vehicle/Test Piece. The test piece shall
be any full vehicle of either Body Frame Integral or
Body on Frame construction that represents
current release status. Deviations shall either be
corrected or noted. The requester shall fully
describe the condition of the full vehicle if it
features non-standard in content.
3.4 Test Time.
Calendar time: 2 days
Test hours: 8 hours
Coordination hours 2 hours
3.5 Test Required Information. Reference
GMW8477.
3.6 Personnel/Skills. Reference GMW8477.
4 Procedure
4.1 Preparation.
4.1.1 Obtain full vehicle Description, Test Data
Log, and Transducer Location forms (see
Appendix C). Enter appropriate information.
4.1.2 Full Vehicle Preparation.
4.1.2.1 Thoroughly inspect the full vehicle to
ensure that requirements specified in sections
Error! Reference source not found. and Error!
Reference source not found. are met.
4.1.2.2 Fill all fluid reservoirs in the full vehicle,
including fuel tank, radiator, overflow tank, brake
fluid reservoirs, engine oil, transaxle fluid, power
steering reservoir, etc.
4.1.2.3 Weigh the full vehicle. Record weight in the
full vehicle description. Note: Test weight does not
include instrumentation.
4.1.2.4 The vehicle should be washed to ensure
clean surfaces for adhesion of transducers.
4.1.3 Component Preparation.
4.1.3.1 Adjust tilt steering columns to eliminate any
relative angle between the lower and upper
steering column. For a telescoping column, locate
the column at the midpoint of its travel.
4.1.3.2 Adjust steering wheel to the center position
with the column lock engaged.
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