1、SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirelyvoluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefro
2、m, is the sole responsibility of the user.”SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions.QUESTIONS REGARDING THIS DOCUMENT: (724) 772-8512 FAX: (724) 776-0243TO PLACE A DOCUMENT
3、 ORDER: (724) 776-4970 FAX: (724) 776-0790SAE WEB ADDRESS http:/www.sae.orgCopyright 1999 Society of Automotive Engineers, Inc.All rights reserved. Printed in U.S.A.SURFACEVEHICLE400 Commonwealth Drive, Warrendale, PA 15096-0001RECOMMENDEDPRACTICESubmitted for recognition as an American National Sta
4、ndardJ2492ISSUEDJUN1999Issued 1999-06Considerations for Suspension ModificationForewordIt is well recognized that a percentage of the motoring public expects to be able to modify their vehiclesuspension ride characteristics from its originally designed and manufactured condition. It is further recog
5、nizedthat certain modifications can have various and potentially serious side effects that must be considered. Thisdocument is intended for use by trained professionals, with access to analytical engineering tools, involved in theengineering and development of aftermarket suspension components and s
6、ystems. This paper is not intended foruse by the consumer or end user. It is also noted that a need exists to communicate the intentions and effects ofa planned change in suspension design, handling, and ride characteristics to the end user. It is the intention of thisdocument to promote a systems a
7、pproach to design as opposed to individual component consideration.The terminology used in this document will be easier to understand and use with reference to SAE J670e.1. ScopeThe scope of this document is limited specifically to the following types of passenger vehicles:automobiles, light trucks,
8、 and sport/utility vehicles. This document addresses modifications as they apply tolegal use of the vehicle, and examines suspension modification as it applies to stock (as manufactured) rideheight, and changed (raised or lowered) ride height. Note that modifications of ride height are considered,ex
9、clusive of wheel and/or tire modifications, which can also have potentially serious side effects, and areoutside the scope of this document.1.1 PurposeThis document is not intended to endorse or discourage modification of original equipment chassisor settings. This paper provides guidelines describi
10、ng some of the issues that must be considered whenundertaking any form of vehicle suspension modification. While every effort has been made to address mosttypes of suspension modification, this document is qualitative and is not all-inclusive. This document is notintended to endorse, regulate, or li
11、mit the degree of modification, or to be interpreted by regulatory orenforcement groups as establishing such limits. Sound engineering principles must be applied in thedevelopment of any and all proposed alterations. It is recommended that all aspects of modification must besupported through analysi
12、s, and should be verified with actual vehicle and/or laboratory testing.2. References2.1 Applicable PublicationThe following publication forms a part of this specification to the extent specifiedherein.2.1.1 ANSI PUBLICATIONAvailable from ANSI, 11 West 42nd Street, New York, NY 10036-8002.ANSI Z535S
13、AE J2492 Issued JUN1999-2-2.2 Related PublicationsFollowing is a list of SAE publications which were reviewed during the compilation ofthis document. While these documents were not specifically referred to in this document, it is felt that they areuseful as references in the application of this docu
14、ment. This list is not all-inclusive. It is up to the individualuser of this document to search for adequate reference material for any modification being considered.2.2.1 SAE PUBLICATIONSAvailable from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001.SAE J193Ball Stud and Socket AssemblyTest
15、ProceduresSAE J274Rated Suspension Spring CapacitySAE J490Surface Vehicle Standard, Ball JointsSAE J491Steering Ball Studs and Socket AssembliesSAE J670eVehicle Dynamics TerminologySAE J1367Performance Test Procedure-Ball Joints and Spherical Rod EndsSAE J1574/2Measurement of Vehicle and Suspension
16、Parameters for Directional Control StudiesSAE 660102Simulation of Field Loading in Fatigue TestingSAE 690234Considerations in Determining Vehicle Handling RequirementsSAE 726019Vehicle HandlingSAE 800845Subjective Evaluation and Vehicle Behavior in Lane - Change ManeuversSAE 806084Vehicle Handling C
17、haracteristics During Braking in a TurnSAE820676Overview of Design Approaches for Optimizing Fatigue Performance of Suspension SystemsSAE 830663Suspension Design for Optimum Road-HoldingSAE 834110The Influence of Different Vehicle Parameters on Steering Controllability and StabilitySAE 834114Influen
18、ce of Front-Wheel Drive on Vehicle Handling at Low Levels of Lateral AccelerationSAE 834115Some Aspects on Suspension Design Parameters for Improved Vehicle Response at theLimit of AdhesionSAE 852184A Study on Vehicle Turning Behavior in Acceleration and BrakingSAE 856040Maneuverability and New Susp
19、ension for Four-Wheel Drive VehiclesSAE 856041Behavior of a Vehicle During TurningSAE 860245The Effects of Tire Camber Angle on Vehicle Controllability and StabilitySAE 861114A Magazines View on Automotive TestingSAE 865087Concept Selection, Analysis and Realization of the Suspension System of a New
20、 Off-RoadVehicleSAE 865114HICASImprovement of Vehicle Stability and Controllability by Rear Suspension SteeringCharacteristicsSAE 865124Steering Geometry Errors Induced by BrakingSAE 865137The Concept of Rear Suspension for Front Drive VehiclesSAE 870241Tire-Pavement InteractionSAE 870495Steady Stat
21、e and Transient Analysis of Ground Vehicle HandlingSAE 870497Investigation into the Effects of Suspension Design of Stability of Light VehiclesSAE 870542Controllability and Stability of Various Types of Four Wheel Drive CarsSAE 870577Suspension Testing Using the Suspension Parameter Measurement Devi
22、ceSAE 871154Simulation of Cornering Properties of a Vehicle Over a Whole Range of Working ConditionsSAE 871940Vehicle Modeling and Service Loads AnalysisSAE 874728The Roll-Centre Concept in Vehicle Handling DynamicsSAE 874810Limit Steady State Vehicle HandlingSAE 8760544WD Vehicle Behavior During Br
23、aking in a TurnSAE 891212Effect of the Nonlinearity of the Suspension Roll Stiffness on the Vehicle HandlingSAE 900666Dynamic Simulation of Chassis Component LoadsSAE 904727Invariant Properties of Automotive SuspensionsSAE 905080Main Steps in the Experimental Tuning Process of a 4WD VehicleSAE 91187
24、2An Investigation of a Road-Vehicle Directional Behavior Under Steady-State ConditionsSAE 92A006A Method for Measuring the Load Condition on a Car SuspensionSAE 921595Combining Properties for Driving Pleasure and Driving Safety: A Challenge for the ChassisEngineerSAE J2492 Issued JUN1999-3-SAE 92504
25、7Vehicle Cornering Behavior Analysis Using a General Purpose Simulation MethodologySAE 930760A Computer Simulation Analysis of Safety Critical Maneuvers for Assessing Ground VehicleDynamic StabilitySAE 940872The Influences of Chassis Geometric Characteristics on Vehicle Dynamic PerformancesSAE 94250
26、5Modeling Steady-State Suspension Kinematics and Vehicle Dynamics of Road Racing CarsSAE 970098Ride and Handling Development of the 1997 Chevrolet Corvette2.2.2 ORIGINAL EQUIPMENT MANUFACTURERS DOCUMENTATIONCare should be taken to obtain the OEMdocumentation available regarding the specific platform
27、 chosen for modification. This documentation shouldinclude, but is not limited to: service manuals, service bulletins, and recall notices. 3. General Considerations3.1 The following are general considerations that must be addressed when applied to any considered suspensionmodification.3.1.1 PHYSICAL
28、/STRUCTURAL ASPECTS OF MODIFICATIONSa. Assure that all add-on components are of sufficient structural capacity to accommodate the loadsincurred during operation, and have proper fit/function.b. Assure that the modifications meet the dimensional constraints defined by the existing chassis andcomponen
29、ts during both static and dynamic conditions.c. Assure that the modifications do not transmit loads to surrounding structural components to the extentthey may fail or wear prematurely.d. Consideration must be given for the ability of the suspension components and chassis system toabsorb and manage r
30、oad induced and crash energy.e. Assure that there is sufficient operating clearance to other components (including the intended wheeland tire selection, and also non-chassis/suspension related components such as brake cables andhoses, wiring, wheel wells, etc.) throughout the full range of suspensio
31、n and steering travel.f. If track width and/or wheelbase dimensions have been changed, assure that all affected componentswill function properly in the new configuration, (including driveshafts and splines, brake cables andhoses for wheelbase length; axle shaft loads, axle/wheel bearing loads, and b
32、alljoint structure for trackwidth).g. Assure that chassis or driveline components have not been forced beyond normal operating limits(examples: tie rod end/balljoint stud articulation, CV joint operating angle)h. Assure that wheel alignment (static and/or dynamic) can be adjusted to minimize tire we
33、ar andhandling compromises. i. It is recommended that component loads be determined through analysis, and confirmed with vehicleand/or laboratory testing. Parts should be life-tested to ensure adequate structural and wear durability.3.1.2 HANDLING AND STABILITY ISSUESa. Make an assessment of the deg
34、ree to which the modifications alter the handling and stabilitycharacteristics of the vehicle under varying load conditions, from curb weight plus driver, to fullGVWRGAWR, under steady state and transient conditions.1. Understeer, oversteer, steering response, directional stability2. Bump steer, rol
35、l steer, compliance steer3. Acceleration and braking performance (squat and dive)4. Cornering capacity (high lateral g conditions)b. Assure that the modifications do not compromise suspension compliance and tire/road surface contactcapability through the range of suspension travel in jounce and rebo
36、und, and under varying roadsurface conditions.SAE J2492 Issued JUN1999-4-c. Quantitative vehicle handling tests should be performed to identify and assess the effects of vehiclechanges as compared to the baseline, or pre-modification vehicle.3.1.3 RIDE COMFORT a. Assess the degree to which the modif
37、ications effect ride comfort.b. Make a judgement as to the acceptability of the trade off of desired performance gains for ride comfort.Determine the need for communication of these changes to the end user.c. Functional and ride evaluation should be performed to confirm changes, and to assure no uni
38、ntendedside effects have arisen.4. Considerations for Vehicles with Originally Designed and Manufactured Ride Height4.1 The following considerations are presented in a tabular (Table 1) format. Columns list potential modifications,and row headings define appropriate considerations. Following are bri
39、ef explanations of these headings asthey apply to vehicles with unmodified ride height. All modifications are considered relative to originalequipment configuration. 4.1.1 DEFINITION OF COLUMN HEADINGS, AND EXPECTED EFFECTSa. Shock SubstitutionIncrease or decrease of rebound and/or compression dampi
40、ng, configurationchanges.1. Damping changes may affect ride comfort, transient under/oversteer characteristics, roll/pitch ratecharacteristics, and traction capability on uneven road surfaces.2. Configuration changes (including minimum compressed and maximum extended limits) must becompatible with s
41、uspension travel.b. Spring SubstitutionIncrease or decrease of spring deflection rate and/or configuration changes.1. Rate changes may affect ride comfort, under/oversteer characteristics, and roll/pitch characteristics.2. Configuration changes (including minimum compressed and maximum extended limi
42、ts) must becompatible with suspension travel.c. Anti-Roll (Stabilizer) BarsIncrease or decrease in roll stiffness, or addition of these components inthe absence of original equipment.1. Changes may affect ride comfort, under/oversteer characteristics, and roll/pitch characteristics.2. Changes may al
43、ter and/or increase the loads seen by the structural components involved. d. Bushing DurometerIncrease or decrease of durometer of existing suspension bushings. 1. Changes may affect ride comfort, under/oversteer characteristics, and roll/pitch characteristics.2. Changes may affect level of noise an
44、d vibration transmitted to the steering wheel and passengercompartment.3. Changes may effect surrounding structural mounts.e. Component SubstitutionReplacement of original equipment components with parts that are ofdifferent construction, but do not modify original equipment suspension geometry (i.e
45、., “heavy duty” or“high performance” direct replacement parts).1. Changes may affect ride comfort, under/oversteer characteristics, and roll/pitch characteristics.2. Changes may affect part longevity.SAE J2492 Issued JUN1999-5-f. Suspension Geometry ModificationComponents that modify the original eq
46、uipment suspensiongeometry.1. Changes may affect ride comfort, under/oversteer characteristics, static/dynamic wheel alignment,and roll/pitch characteristics.4.1.2 ROW HEADINGSa. Component ClearanceReference 3.1.1 of this documentb. Wheel AlignmentReference 3.1.1 of this documentc. Tire WearReferenc
47、e 3.1.1 of this document d. Stress on Surrounding ComponentsReference 3.1.1 of this documente. Energy ManagementReference 3.1.1 of this documentf. Over/UndersteerReference 3.1.2 of this documentg. Steering ResponseReference 3.1.2 of this documenth. Compliance/TractionReference 3.1.2 of this document
48、i. Vehicle StabilityReference 3.1.2 of this documentj. Acceleration/BrakingReference 3.1.2 of this documentk. Ride ComfortReference 3.1.3 of this documentl. Ground Clearance TABLE 1CONSIDERATIONS FOR VEHICLES WITH ORIGINALLY DESIGNEDAND MANUFACTURED RIDE HEIGHTModificationConsiderationsShockSubstitu
49、tionSpringSubstitutionAnti-Roll(Stablizer)BarsBushingDurometerComponentSubstitutionSuspensionGeometryModificationComponent Clearance 1 1 2 2 See Table 2Wheel alignment 1 2 See Table 2Tire wear 1 1 2 1 2 See Table 2Stress on surrounding components 2 2 2 2 2 See Table 2Energy management 2 2 2 1 2 See Table 2Over/Under Steer 1 2 2 1 2 See Table 2Steering response 1 1 2 1 2 See Table 2Compliance/Traction 2 2 2 2 2 See Table 2Vehicle Stability 1 2 2 1 2 See Table 2Acceleration/braking 1 2 1 1 2 See Table 2Ride Comfor
