Patent Publication Number: US-8109528-B2

Title: Service load bearing assembly for spreading out high induced stresses

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 12/280,511, filed Aug. 22, 2008 now U.S. Pat. No. 7,914,021, which is the National Stage of International Application No. PCT/US07/24212, filed Nov. 19, 2007, which claims the benefit of U.S. Provisional Application No. 60/866,347, filed Nov. 17, 2006, each application of which is hereby incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The embodiments disclosed herein relate generally to the field of suspension systems for vehicles, and more particularly to an offset bushing mounting apparatus for use in the suspension systems of vehicles. 
     BACKGROUND OF THE INVENTION 
     Suspension systems making use of elastomeric members or bushings between a generally fixed portion of the frame of the vehicle and an end of a shock absorber, strut, or other type of cylinder or suspension member are generally well known within the art. 
     Elastomeric bushings are generally used to reduce transmitted road noise and suspension vibration, and are also generally flexible enough to allow for articulation or movement during suspension travel. Typically, a suspension arm includes at least one elastomeric bushing pivotably attached to the vehicle frame. 
     In some car and light truck suspensions, tight clearances between the wheel or other components and suspension components require bushings that are offset or cantilevered from the suspension component. Typically, the geometric relationship of the cantilevered bushing to the suspension component induces high bending moments on the interface of the bushing and the suspension component during vehicle service. More specifically, service loads induce high bending moments, and subsequently high local stresses, in the portion of the suspension components connected to the bushing. Referring to  FIG. 1 , a force F of 33.2 kN to an offset bushing, as typically experienced in automotive or light truck applications, results in a stress of greater than 600 MPa being induced to the suspension component  10  at the point of connectivity  100  to the offset bushing. These high local stresses require that the suspension component  10  be constructed from high strength materials, i.e. forged steel, which precludes the use of lightweight materials, i.e. cast aluminum. By precluding the use of lightweight materials, the weight of heavier prior offset bushing designs disadvantageously limit the fuel economy and handling of the vehicle. 
     In light of the above, a need exists for an offset bushing design incorporated into lightweight suspension components, such as cast aluminum suspension components. 
     SUMMARY OF THE INVENTION 
     Embodiments of the present invention may overcome the drawbacks associated with the prior art by providing a lightweight suspension component having an offset bushing assembly. Systems and methods for providing a lightweight suspension component having an offset bushing assembly are disclosed herein. According to aspects illustrated herein, there is provided a suspension assembly including a bolt made from a bolt material; a suspension component made from a suspension material, the suspension component having a suspension opening therethrough, the suspension opening having a geometry for insertion of at least a first portion of the bolt; and a bushing assembly including an elastomeric element and a bushing opening therethrough, the bushing opening having a geometry for insertion of at least a second portion of the bolt; wherein the suspension material has a yield strength that is substantially higher than a yield strength of the bolt material. 
     According to aspects illustrated herein, there is provided a suspension assembly including a suspension component including at least one substantially cylindrical cavity positioned at one end of the suspension component, the cylindrical cavity providing for attachment to a vehicle frame and having a bore at one end of the cylindrical cavity; a stud positioned centrally in the at least one substantially cylindrical cavity, the stud having a head opposed to enlarged bore of the cylindrical cavity of the suspension component and providing the pivot axis of the suspension component to a vehicle frame; a hardened sleeve in a pressed interference-fit engagement to the enlarged bore of the cylindrical cavity; a bushing assembly including an elastomeric element having a core with a centrally positioned hollow, wherein the hollow of the core has a geometry for insertion of the stud; and a fastener in engagement to the stud, wherein the core is positioned between the fastener and the hardened sleeve. 
     According to aspects illustrated herein, there is provided a method of manufacturing a suspension assembly including providing a suspension component including at least one cavity positioned at one end of the suspension component, the at least one cavity providing for attachment to a vehicle frame, the at least one cavity having an enlarged bore at one end thereof; positioning a stud in the at least one cavity of the suspension component, the stud having a head in contact with a portion of the suspension component opposed to the enlarged bore of the at least one cavity of the suspension component; positioning a sleeve over the stud and adjacent to the enlarged bore of the at least one cavity of the suspension component; positioning a bushing assembly having an elastomeric element with a core, the core having a first end, a second end and a hollow, wherein the stud is positioned within the hollow of the bushing assembly and the first end of core is adjacent to the sleeve; and engaging a fastener adjacent to the second end of the core and in threaded connection to the stud, wherein full engagement of the fastener further presses the sleeve into the enlarged bore of the at least one cavity and clamps the core of the bushing to the sleeve. 
     Various embodiments provide certain advantages. Not all embodiments of the invention share the same advantages and those that do may not share them under all circumstances. Further features and advantages of the embodiments, as well as the structure of various embodiments are described in detail below with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The presently disclosed embodiments will be further explained with reference to the attached drawings, wherein like structures are referred to by like numerals throughout the several views. The drawings shown are not necessarily to scale, with emphasis instead generally being placed upon illustrating the principles of the presently disclosed embodiments. 
         FIG. 1  is a stress diagram of an illustrative embodiment of a prior suspension component having a prior offset bushing design; 
         FIG. 2  is a perspective view of an illustrative embodiment of a suspension component having an offset bushing assembly; 
         FIG. 3  is a cross-sectional view of an illustrative embodiment taken along section line  2 - 2  of the offset bushing depicted in  FIG. 2 ; 
         FIG. 4  is a stress diagram of an illustrative embodiment of an offset bushing and suspension component; 
         FIG. 5  is a stress diagram of all illustrative embodiment of an offset bushing and suspension component; 
         FIG. 6  is a stress diagram of an illustrative embodiment of an offset bushing and suspension component; 
         FIG. 7  is a stress diagram of an illustrative embodiment of an offset bushing and suspension component; 
         FIG. 8  is a cross-sectional view of an illustrative embodiment of an offset suspension bushing; 
         FIG. 9  is a stress diagram of the offset suspension bushing of  FIG. 8 ; 
         FIG. 10  is a cross-sectional view of an illustrative embodiment of an offset suspension bushing; 
         FIG. 11  is a stress diagram of the offset suspension bushing of  FIG. 10 ; 
         FIG. 12  is a cross-sectional view of an illustrative embodiment of an offset suspension bushing; and, 
         FIG. 13  is a stress diagram of the offset suspension bushing of  FIG. 12 . 
     
    
    
     While the above-identified drawings set forth presently disclosed embodiments, other embodiments are also contemplated, as noted in the discussion. This disclosure presents illustrative embodiments by way of representation and not limitation. Numerous other modifications and embodiments can be devised by those skilled in the art which fall within the scope and spirit of the principles of the presently disclosed embodiments. 
     DETAILED DESCRIPTION OF THE DRAWINGS 
     The inventions are not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The inventions are capable of being arranged in other embodiments and of being practiced or of being carried out in various ways. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having,” “containing,” “involving,” and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. 
     Aspects of the inventions are described below with reference to illustrative embodiments. It should be understood that reference to these illustrative embodiments is not made to limit aspects of the inventions in any way. Instead, illustrative embodiments are used to aid in the description and understanding of various aspects of the inventions. Therefore, the following description is intended to be illustrative, not limiting. 
     Embodiments of the present invention are directed to a disposable apparatus. As shown in the embodiment of  FIG. 2 , a suspension component  10  may have an offset bushing assembly  15 . The suspension component  10  may be a triangular A-arm configuration in which one end, forming the vertex  12  of the triangle, may provide for engagement to a ball joint or equivalent structure, and may further include two suspension legs  13   a ,  13   b  extending from the vertex  12  of the suspension component  10  and may provide for a pivoting engagement to a vehicle frame (not shown). The pivoting engagement may be provided by cavities  11 , having a substantially cylindrical configuration, formed through the portion of the suspension legs  13   a ,  13   b  attached to the vehicle frame in combination with bushings connected to the cavities  11 , wherein at least one bushing may be an offset bushing assembly  15 . In some embodiments, a first suspension leg  13   a  may be connected to the vehicle frame by an offset bushing assembly  15 , and the second suspension leg  13   b  may be connected to the vehicle frame by a conventional bushing assembly, in which the conventional bushing may fit within the cavity  11 . 
     Although the suspension component  10  is depicted as having the configuration of a triangular A-arm, the suspension component  10  may be any suspension member that is utilized in automotive applications including but not limited to: swing arm, control arm, drag link, differential link, camber link, lateral link, trailing arm, strut rod, trailing arm, tie rod, knuckle, wheel carrier, subframe, axle carrier, crossmember, subframe and toe rods. In addition, the suspension component may be used on any vehicle, including but not limited to an automobile, truck, semi, bus, van, minivan, sports utility vehicle (SUV), motorcycle, bicycle, scooter, carriage, train, boat, ship, submarine, amphibious vehicle, all-terrain vehicle (ATV), aeroplane, rotorcraft, or any other device or structure for transporting persons or things. Not all embodiments of the present invention are intended to be limited in these respects. 
     The suspension component  10  may be composed of a lightweight material. Using a lightweight material may contribute to increasing at least one of the performance and fuel economy of the vehicle. The suspension component  10  may be composed of an aluminum alloy, for example, Aluminum Association A356. In some embodiments, the aluminum alloy may be composed of from about 6.5 wt. % to about 7.5 wt. % Al, less than 0.20 wt. % Fe, less than 0.20 wt. % Cu, less than 0.10 wt. % Mn, from about 0.25 wt. % to about 0.45 wt. % Mg, less than 0.10 wt. % Zn, less than 0.20 wt. % Ti, and a balance of Al and incidental impurities. Incidental impurities may include any contamination of the melt, including leaching of elements from the casting apparatus. Allowable ranges of impurities may be less than 0.05 wt. % for each impurity constituent and 0.15 wt. % for total impurity content. In some embodiments, the casting may be heat treated to a T5 or T6 temper. In some embodiments, the temper may be a T6 temper. 
     The suspension component may be cast using permanent mold casting technology, sand casting technology, or a Vacuum Riserless Casting (VRC)/Pressure Riserless Casting (PRC). The Vacuum Riserless Casting (VRC)/Pressure Riserless Casting (PRC) process may be suitable for mass production of high integrity aluminum automotive suspension components. VRC/PRC is a low pressure casting process, in which in some embodiments the pressure may be on the order of 6.0 Psi. In some embodiments the pressure may be between approximately 3.5 Psi and approximately 8.5 Psi, may be less than 6.0 Psi or may be greater than 6.0 Psi as not all embodiments of the present invention are intended to be limited in this respect. In VRC/PRC, a mold may be positioned over a hermetically sealed furnace and the casting cavity may be connected to the melt by feed tubes. Melt may be drawn into the mold cavity by applying a pressure to the furnace through the application of an inert gas, such as Argon. A constant melt level may be maintained in the·furnace of the VRC/PRC apparatus, which may assist in avoiding back-surges that are sometimes experienced in a more traditional low-pressure system. 
     Multiple fill tubes (stalks) may provide for metal distribution in the mold cavity. Multiple fill points combined with close coupling between the mold and melt surface may allow for lower metal temperatures, may minimize hydrogen and oxide contamination and/or may provide maximum feeding of shrinkage-prone areas in the casting. The multiple fill tubes may also allow multiple yet independent cavities in a mold. Carefully sequenced thermal controls may quickly solidify castings from extreme back to fill tubes, which may then function as feed risers. 
     The suspension component may be a hollow casting. Although, in some embodiments, the suspension component  10  may be cast, the suspension component may be formed or forged. 
     The embodiment depicted in  FIG. 3  shows a cross sectional view of along section line  2 - 2  of the offset bushing assembly  15  connected to the first suspension leg  13   a , as depicted in the embodiment shown in  FIG. 2 . The cavity in the first suspension leg  13   a  may further include an enlarged bore  16 . The enlarged bore  16  may have a width W 1  and length L 1  dimension which may provide for a frictional and/or Interference-fit engagement to the hardened sleeve  25  of the offset bushing assembly  15 . In some embodiments, a hardened sleeve may have a strength which is greater than a normal material by subsequent processing in an attempt to increase wear and resist higher stresses without failure. 
     In some embodiments, the enlarged bore  16  may be machined into the cavity  16  of the first suspension leg  13   a . The portion of the suspension component  10  corresponding to the cavity  11  may have a first flange  14   a  corresponding to a first opening  17   a  of the cavity  11  having the enlarged bore  16 , and a second flange  14   b  corresponding to a second opening  17   b  of the cylindrical cavity  11  that is opposed to the enlarged bore  16 . The first and second flanges  14   a ,  14   b  may strengthen the portion of the suspension component  10  corresponding to the cavity  11  and may provide sufficient area to react to loads of head portion  21  of the stud  20  and lateral rim portion of the hardened steel sleeve  25  and in some embodiments, react without deformation. 
     Referring to  FIG. 2  and  FIG. 3 , in one embodiment, the offset bearing assembly  15  includes a stud  20 , a sleeve  25 , a fastener  30 , and a bushing assembly including an elastomeric element  40 . Referring to  FIG. 3 , the stud  20  may be formed from hardened steel and may include a head portion  21  and a threaded portion  22 . The head portion  21  has a width W 3  greater than the width W 4  of the first opening  17   a , wherein the width of the first opening  17   a  is substantially equal to provide an interference fit to the width of the cylindrical cavity  11  prior to the enlarged bore  16 . The threaded portion  22  may extend a portion of the longitudinal length L 2  of the stud  20  or may be positioned only to correspond with the threaded fastener  30 . 
     The sleeve  25  may be composed, such as by forming or casting, of a material having a higher hardness than the suspension component  10 . In some embodiments, this material may be hardened steel. The sleeve  25  may have a width for frictional engagement of the exterior surface of the longitudinal body portion  18  of the hardened sleeve  25  to the interior surface of the enlarged bore  16  in a pressed interference-fit engagement. Specifically, the properties of the pressed engagement may be enhanced by selecting the width of W 1  of the enlarged portion  16  of the cavity, the width W 2  of the hardened sleeve  25 , the wall thickness T 1  of the hardened sleeve  25 , and the thickness of W 5  of the suspension leg  13  to provide a compressive force induced by the interior surface of the enlarged portion  16  of the cavity  11 . This compressive force is the mechanism that provides the sufficient normal force to frictionally engage hardened sleeve  25  and enlarged portion  16  of cavity  11 . 
     In some embodiments, choosing a material which is harder or has a higher yield strength for a first part, such as the stud and/or bolt, may enable a lower strength and/or lighter weight material to be used for another part, such as the boss or suspension component. The yield strength or yield point of a material is the stress at which the material begins to deform plastically. Prior to the yield point, a material may deform elastically and will return to its original shape when an applied stress is removed. Once the yield point of a material is passed, some fraction of deformation will be permanent and non-reversible. A material&#39;s yield point may be defined as the material&#39;s true elastic limit, e.g., the lowest stress at which dislocations move, as the material&#39;s proportionally limit, e.g., the point at which the stress-strain cure deviates from Hooke&#39;s law (i.e., becomes non-linear), as the material&#39;s elastic limit, e.g., the lowest stress at which permanent deformation may be measured, as the material&#39;s offset yield point (yield strength or proof stress), e.g., the point on the stress strain curve, typically defined by a plastic strain of 0.2%, and/or as the material&#39;s upper and/or lower yield points, e.g., the point at which the material reaches an upper yield point before dropping rapidly to a lower yield point, wherein the material response may be linear up until the upper yield point, but the lower yield point may be used in structural engineering as a conservative value. 
     In some embodiments, the boss or suspension component may be made from a first material and the stud or bolt may be made from a second material. The second material may have a yield strength that is substantially higher than the yield strength of the first material. In some embodiments, the second material may have a yield strength that is two or three times higher than the yield strength of the first material. In some embodiments, the second material may have a yield strength that is more than three times higher than the yield strength of the first material. In some embodiments, the first material may have a yield strength of approximately 200 MPa. In some embodiments, the yield strength of the first material may range from approximately 100 MPa to approximately 300 MPa. The yield strength of the first material may be less than 100 MPa or may be greater than 300 MPa, as not all embodiments of the present invention are intended to be limited in this respect. In some embodiments, the second material may have a yield strength of approximately 800 MPa. In some embodiments, the yield strength of the second material may range from approximately 600 MPa to approximately 800 MPa and/or from approximately 800 MPa to approximately 1000 MPa. The yield strength of the second material may be less than 600 MPa or may be greater than 1000 MPa, as not all embodiments of the present invention are intended to be limited in this respect. In some embodiments, the second material may include steel or titanium or any other material having a higher yield strength than the first material, which may include, but is not limited to, aluminum or magnesium alloys, or a lower strength steel or iron. 
     It should be appreciated that in some embodiments, some of the components or parts of the bushing suspension may be made from a higher or lower yield strength materials, as not all embodiments of the present invention are intended to be limited in this respect. 
     The longitudinal body  18  portion may have dimensions for insertion of the hardened sleeve  25  within the enlarged bore  16  of the cavity  11 . The hardened sleeve  25  may further include a lateral rim portion  17  extending along an exterior surface of the first flange  14   a  of the suspension component  10 . The lateral rim  17  may facilitate distribution of the load stresses induced in the bushing assembly during service to the suspension component  10  in a uniform manner. 
     In one embodiment, the bushing assembly may include an elastomeric element  40  having a rigid core  35  with a centrally positioned hollow. The elastomeric element may be provided by a polyurethane or rubber bushing. In some embodiments, the elastomeric element may be provided by a hydraulic bushing. The hydraulic bushing may include a polyurethane or rubber skin encasing hydraulic oil. Hydraulic bushings may be tuned for a specific frequency and provide increased damping at the tuned frequency. Compared to a much stiffer conventional bushing, a hydraulic bushing may provide a lower spring rate for improved isolation but much higher damping for adequate control. A hydraulic bushing may produce high damping as a result of the transfer of fluid from one chamber to another. The fluid may pass through a channel called the inertia track. The inertia track can be ‘tuned’ to provide damping at a specific frequency. It should be appreciated that any bushing, such as solid bushings, may be utilized. 
     The rigid core  35  may be provided by a lightweight material, such as aluminum, having sufficient wall thickness to provide structural rigidity. The hollow that is centrally positioned has a width sufficient for insertion of the stud  20 . In some embodiments, a core flange  36  may be provided at the end of the rigid core  35  that is opposite the hardened sleeve  25  and engaged by the fastener  30 . The core flange  36  may reinforce the site at which the fastener  30  engages the rigid core  35  in order to clamp it against the hardened sleeve  25  in frictional and interference-fit engagement to the enlarged bore  16  of the cavity  11 . 
     The fastener  30  positioned at the end of the rigid core  35  opposite the hardened sleeve  25  may be engaged to the stud  20  in communicating threaded engagement. The fastener  30  may have a width W 6  that is sufficiently greater than the width of the hollow centrally positioned in the rigid core  35 . Torquing the fastener  30  into contact with the core flange  36  may induce a force on the sleeve  25  through the contact of the rigid core  35  to the lateral rim portion  17  of the sleeve  25 , wherein continued torquing of the fastener  30  towards the cavity  11  of suspension component  10  may further press the hardened sleeve  25  into frictional engagement with the enlarged bore. In some embodiments, the fastener  30  may be composed of a hardened steel or another high yield strength material. 
     In another aspect of the present invention, a method of forming a suspension component assembly having an offset bushing is provided. The method may include the steps of providing a suspension component  10  including at least one substantially cylindrical cavity  11  positioned at one end of the suspension component  10 , the cylindrical cavity  11  providing for attachment to a vehicle frame and having an enlarged bore  16  at one end of the cylindrical cavity  11 ; positioning a stud  20  centrally in the at least one substantially cylindrical cavity  11  of the suspension component  10 , the stud  20  having a head  21  in contact with a portion of the suspension component  10  opposed to enlarged bore of the cylindrical cavity  11  of the suspension component; positioning a hardened sleeve  25  over the stud  20  and adjacent to the enlarged bore  16  of the cylindrical cavity of the suspension component  10 ; positioning a bushing assembly having an elastomeric element  15  with a rigid core, the rigid core  35  having a first end, a second end and a centrally positioned hollow, wherein the stud  20  is positioned within the centrally positioned hollow of the bushing assembly  15  and the first end of rigid core  35  is adjacent to the hardened sleeve  25 ; and engaging a fastener  30  adjacent to the second end of the rigid core  35  and in threaded connection to the stud, wherein full engagement of the fastener  30 , clamps the rigid core  35  of the elastomeric element  15  to the hardened sleeve  25 , further pressing the hardened sleeve  25  into the enlarged bore  16  of the cylindrical cavity  11 . 
     In one embodiment, a suspension assembly includes a suspension component including at least one substantially cylindrical cavity positioned at one end of the suspension component, the cylindrical cavity providing for attachment to a vehicle frame and having an enlarged bore at one end of the cylindrical cavity; a stud positioned centrally in the at least one substantially cylindrical cavity, the stud having a head opposed to enlarged bore of the cylindrical cavity of the suspension component and providing the pivot axis of the suspension component to a vehicle frame; a hardened sleeve in a pressed engagement to the enlarged bore of the cylindrical cavity; a bushing assembly including an elastomeric element having a rigid core with a centrally positioned hollow, wherein the hollow of the rigid core has a geometry for insertion of the stud; and a fastener in engagement to the stud, wherein the rigid core is positioned between the fastener and the hardened sleeve. 
     In some embodiments, the suspension component may be cast from a lightweight and/or lower yield strength material, such as an aluminum alloy, and at least one of the stud and the hardened sleeve may be formed of steel or a higher yield strength material. The hardened sleeve may provide a relatively high strength material that uniformly distributes the service loads induced to the offset bushing to the lightweight cast suspension component. 
     In some embodiments, the suspension component may include an aluminum alloy. In some embodiments, the suspension component may include at least one of a swing arm, a control arm, a drag link, a differential link, a camber link, a lateral link, a trailing arm, a strut rod, a trailing arm, a tie rod, a knuckle, a wheel carrier, a subframe, an axle carrier, a crossmember, a subframe and a toe rod. In some embodiments, the suspension component may have an A-arm configuration, having at least two cylindrical cavities providing for attachment to a vehicle frame. In some embodiments, the hardened sleeve may include steel. In some embodiments, the core of the bushing assembly may be a rigid core and may include steel. In some embodiments, the rigid core may include an enlarged flange positioned adjacent to the fastener. 
     In some embodiments, the end of the suspension component having the substantially cylindrical cavity may have a first flange corresponding to a first opening of the cylindrical cavity having the enlarged bore and a second flange to a second opening of the cylindrical cavity opposed to the enlarged bore. In some embodiments, the hardened sleeve may include a longitudinal body portion and a lateral rim portion; the longitudinal portion may have dimensions for insertion to the enlarged bore of the cylindrical cavity and the lateral rim portion may extend along an exterior surface of the first flange of the suspension component. In some embodiments, the hardened sleeve may uniformly distribute service loads induced to the bushing assembly to the suspension component. In some embodiments, the elastomeric element may be a hydraulic bushing. In some embodiments, the elastomeric element may include polyurethane, rubber or a combination thereof. In some embodiments, the stud may include steel. 
     Some embodiments of the suspension assembly of the present invention may provide for a more uniform distribution of the bending stresses in the main body of the suspension component  10  generated by an offset bushing configuration than were previously possible in prior offset bushing configurations. In some embodiments, the hardened sleeve  25  may more uniformly distribute highly concentrated stresses at the pivot axis of the bushing assembly to the lower-strength material of the suspension component. 
     The embodiments depicted in  FIGS. 4-7  show stress distributions measured in one embodiment of the offset bushing and suspension component assembly, wherein a force F of 33.2 kN is being subjected to the bushing, as typically experienced in automotive or light truck applications.  FIG. 4  depicts the stress distribution throughout the entire structure.  FIG. 5  depicts the stress distribution to the structure without showing the rigid collar  35 .  FIG. 6  depicts the stress distribution to the structure without showing the rigid collar  35  and stud  20 .  FIG. 7  depicts stress distribution in the suspension component  10  without showing the rigid collar  35 , the stud  20 , and the hardened sleeve  17 . As depicted in  FIG. 7 , a measurable reduction in the stress induced to the suspension component  10  may be provided by the hardened sleeve  17  and offset bushing assembly, wherein a reduction in stress to less than 300 MPa at the connection  100  of the bushing  15  to the suspension component  10  allows for the use of lightweight aluminum alloy suspension components in an advantageous manner, such as an economical manner. 
     As shown in the embodiments depicted in  FIG. 8 , a sleeve  202  may be used to transmit a load from a bushing (not shown) to a suspension component, which may contain or may be rigidly affixed to a boss  204 . The sleeve  202  may be a stepped, hardened steel sleeve and may be designed to withstand high stresses without permanent deformation or fracture. The sleeve  202  may be designed to spread out the load from the bushing to a large contact area of the suspension component or boss  204 . The boss  204  may be formed separately from or integrally with the sleeve  202 . In some embodiments, the boss  204  is made from cast aluminum. The boss  204  may be aligned with the sleeve  202  to enable a bolt  210  to be inserted through bores  206 ,  208  of the sleeve  202  and boss  204 , respectively. The bolt  210  may be threaded into a fastener, such as a nut (not shown), on the outside of the bushing inner sleeve to hold the bolt  210  in place. This configuration may clamp the bushing inner metal and sleeve  202  to the boss  204 , thereby contributing to proper load transfer through frictional forces. Stresses acting on the boss  204 , for example stresses due to service loading, may be effectively reduced such that a lower-strength material can now be utilized and may withstand repeated application of the service load. An exemplary stress distribution is represented in the embodiment shown in  FIG. 9 . 
     In some embodiments, an adaptor or connector may be utilized to transmit a load from a bushing to a suspension component, similar to the sleeve  202  of the previous embodiment. As shown in the embodiment depicted in  FIG. 9 , a cantilever bushing joint  220  may include a boss  222  and a bushing  224  connected to the boss via an adaptor  226 . The bushing  224  may be press fit or interference fit onto the adaptor  226 . The adaptor  226  may connect with the boss  222  via a contact surface  228 . 
     The contact surface  228  may be formed in mushroom or convex shape, which may improve stress distribution for the contact surface  228  between the adaptor  226  and the suspension component or the boss  222 . A contact surface with a mushroom shape may also limit and resist slippage between the adaptor and the suspension component. In some embodiments, the adaptor  226  is made of a material which can withstand high stresses without significant or any deformation, similar to a steel sleeve  202  as described above. 
     A bolt  230  may be inserted through bores of the boss  222 , adaptor  226  and bushing  224 . The bolt  230  may be secured in place using any means, such as a nut  232  or other fastener positioned a distal end  234  of the bushing  224 . In some embodiments, the nut  232  may be threaded onto the steel bolt  230  outside of the bushing inner sleeve, which may clamp the bushing inner metal and adaptor to the suspension component, assisting in attaining proper load transfer through frictional forces. The stresses acting on the suspension component due to the service loading may be effectively reduced such that a lower-strength material can now be utilized, and may withstand repeated application of the service load. An exemplary stress distribution is represented in the embodiment shown in  FIG. 11 . 
     In some embodiments, the adaptor portion may be combined with the bushing inner sleeve, as shown in the embodiment depicted in  FIG. 12 . The cantilever bushing joint  240  may include a boss  242  and an integrated bushing sleeve  244 . The integrated bushing sleeve  244  may be designed to transmit a load from the bushing to the suspension component or the boss  242 , similar to the steel sleeve  202  of  FIG. 8 . The contact surface  246  may be formed in a mushroom shape, which may better distribute stress between the bushing and the suspension component. As described above, the bushing sleeve may be made of a material which can withstand high stresses without significant or any deformation. In some embodiments, a steel bolt  248  may be secured by a nut  250  threaded onto a distal end  252  of the steel bolt  148 . An exemplary stress distribution is represented in the embodiment shown in  FIG. 13 . In some embodiments having an integrated bushing sleeve, the bushing inner metal may be made of a similar or the same high yield strength material as the adaptor  226  of the embodiment depicted in  FIG. 10 ; this material may be needed to withstand service-induced stresses. 
     It should be appreciated that interference fit or press fit may imply that one part is pressed into another part to hold the first part in place. In some embodiments, the first part may have a bigger diameter than an opening in the second part into which the first part is inserted. When the first part is inserted or forced into the opening in the second part, the second part may deform to accommodate the first part. This deformation may be microscopic or visible with the naked eye. The first part may then be held by frictional forces caused by the normal forces of the second part trying to return to its original shape. In other words, the elastic deformation of the second part may hold the first part in place by substantial frictional force between the parts. 
     It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.