Vehicle suspension bushing assembly with two-piece bar pin and method of assembling the same

A bushing assembly, such as for a vehicle suspension, includes inner and outer sleeves, a bushing disposed radially between the inner and outer sleeves, and a two-piece bar pin. The two-piece bar pin is configured such that a first inboard end of a first bar pin component is received in one end of the inner sleeve and a second inboard end of a second bar pin component is received in the other end of the inner sleeve. One or both of the first and second inboard ends of the first and second bar pin components has a closed end bore such that the first and second bar pin components cooperate to form a closed cavity within the two-piece bar pin assembly for weight saving purposes when the first and second inboard ends of the first and second bar pin components are pressed into the inner sleeve.

FIELD

The subject disclosure relates to vehicle suspension bushing assemblies and to methods of assembling vehicle suspension bushing assemblies.

BACKGROUND

Automobiles, trucks, buses and other vehicles are commonly designed with suspension systems that are connected by bushings to the vehicle chassis. For example, heavy vehicles such as semi-trucks that are equipped with solid axles commonly use leaf spring suspension systems where one end of the leaf springs are attached to a frame-mounted bracket by a heavy-duty bushing assembly. Such bushing assemblies decouple torsional input from other articulation directions. Each bushing assembly typically consists of an outer metal sleeve that is pressed into one end of the leaf spring, an elastomeric bushing positioned within the outer metal sleeve, an inner metal sleeve that extends through the center of the elastomeric bushing, and a one-piece bar pin that extends through the inner metal sleeve. Each end of the bar pin includes a hole that receives a bolt to bolt each end of the bar pin to the frame-mounted bracket.

The elastomeric bushing operates to isolate the vehicle from shock. The elastomeric bushing, which is located between the outer and inner metal sleeves, effectively isolates the vehicle frame from the unsprung components of the vehicle, such as the axle and wheel assemblies, and permits limited degrees of axial (longitudinal), radial (transverse), and pivotal (gimbaling) motion between the inner metal sleeve relative to the outer metal sleeve. In certain high load applications, the ends of the outer metal sleeve are curved or bent at least partially over the ends of the elastomeric bushing in order to further encapsulate the elastomeric bushing, which can improve the radial spring rate, the axial spring rate, the axial retention, and the durability of the elastomeric bushing.

While these elastomer isolated bushing assemblies have performed satisfactorily in the field, they are not light weight. Thus, there remains a need for the development of new bushing assemblies that are optimized for weight savings without compromising their noise, vibration, and harshness (NVH) performance, strength, and durability and without increasing manufacturing costs.

SUMMARY

The subject disclosure relates to an improved bushing assembly of the type that may be used in a vehicle suspension system, for example. The improved bushing assembly includes an inner sleeve, an outer sleeve, a bushing disposed radially between the inner and outer sleeves, and a two-piece bar pin assembly that extends through the inner sleeve. The inner sleeve extends longitudinally between a first inner sleeve end and a second inner sleeve end. The inner sleeve extends annularly about a longitudinal axis, while the outer sleeve extends annularly about the inner sleeve in a radially spaced relationship. The two-piece bar pin assembly includes a first bar pin component and a second bar pin component. The first bar pin component extends longitudinally between a first inboard end and a first outboard end. The second bar pin component extends longitudinally between a second inboard end and a second outboard end. The two-piece bar pin assembly is arranged/assembled such that the first and second inboard ends of the first and second bar pin components are received in the inner sleeve in a press fit with the first and second inboard ends of the first and second bar pin components abutting one another.

In accordance with another aspect of the present disclosure, a bushing assembly is provided which includes an inner sleeve, an outer sleeve, a bushing disposed radially between the inner and outer sleeves, and a two-piece bar pin assembly that extends through the inner sleeve. The inner sleeve extends longitudinally between a first inner sleeve end and a second inner sleeve end. The inner sleeve extends annularly about a longitudinal axis, while the outer sleeve extends annularly about the inner sleeve in a radially spaced relationship. The two-piece bar pin assembly includes a first bar pin component and a second bar pin component. The first bar pin component extends longitudinally between a first inboard end and a first outboard end. The second bar pin component extends longitudinally between a second inboard end and a second outboard end. The two-piece bar pin assembly is arranged/assembled such that the first and second inboard ends of the first and second bar pin components are received in the inner sleeve. In addition, at least one of the first and second inboard ends of the first and second bar pin components has a closed end bore such that the first and second bar pin components cooperate to form a closed cavity within the two-piece bar pin assembly for weight saving purposes.

The design of the two-piece bar pin described herein is particularly advantageous because it provides weight savings with improved manufacturability and reduced scarp material losses that can reduce manufacturing costs. At the same time noise, vibration, and harshness (NVH) performance, strength, and durability of the bushing assembly can be maintained or improved.

In accordance with another aspect of the present disclosure, a method of assembling the bushing assemblies described above is also disclosed. The method includes the steps of: forming an inner sleeve with first and second inner sleeve ends, arranging an outer sleeve annularly about the inner sleeve such that the outer sleeve and the inner sleeve are radially spaced from one another and are concentrically aligned about a longitudinal axis, and molding a bushing of elastomeric material between the outer sleeve and the inner sleeve. The method further comprises the step of forming a two-piece bar pin by individually forming first and second bar pin components, where the first bar pin component is formed to include a first inboard end and a first outboard end and the second bar pin component is formed to include a second inboard end and a second outboard end. The method proceeds with the step of pressing the first inboard end of the first bar pin component into the first inner sleeve end and pressing the second inboard end of the second bar pin component into the second inner sleeve end until the first and second inboard ends of the first and second bar pin components abut one another inside the inner sleeve.

Advantageously, the process allows the two-piece bar pin assembly to be formed by cold forming, such as by a cold heading process, or a hot forming process, such as a hot forging process, both of which allow for the addition of weight reducing features without the generation of scrap material like that which would be produced by a machining operation. In addition, cold forming creates compacted areas of greater density in the first and second bar pin components, which increases the strength of the first and second bar pin components. Alternatively, one or more machining processes can be used to manufacture the two-piece bar pin assembly. When machining is used, the weight savings advantage is still achieved, even if scrap reduction is not improved.

DETAILED DESCRIPTION

Referring to the Figures, wherein like numerals indicate corresponding parts throughout the several views, various bushing assemblies10,20,20′ are illustrated.

Bushing assemblies are generally used in a wide range of different applications. Thus, it should be appreciated that the scope of the subject disclosure is not necessarily limited to any particular application or applications. Notwithstanding the wide range of potential applications in which the subject disclosure might find utility, the bushing assemblies shown in the illustrated examples are designed for use in vehicles, such as heavy trucks, semi-tractors, buses, and the like. Heavy vehicles of this type are commonly designed with suspension systems that are connected by bushing assemblies10to a chassis of the vehicle. One common type of suspension system used in heavy truck/vehicle applications uses leaf springs that are mounted to the chassis (e.g., frame) of the vehicle. Such vehicles typically have solid axles that support and drive wheel assemblies mounted on opposing ends of each solid axle.

A typical heavy truck/vehicle suspension system22is illustrated inFIG.1. The vehicle suspension system22comprises a leaf spring24that extends generally fore and aft before a front leaf spring end26and a rear leaf spring end28. The front leaf spring end26is pivotally connected to a frame bracket30by bushing assembly10. The frame bracket30is fixedly connected to the frame (not shown) or other support structure of the vehicle, which forms the vehicle chassis. In traditional designs, the bushing assembly10includes an outer metal sleeve32that is pressed into a loop34in the front leaf spring end26and a one-piece bar pin36that extends through the outer metal sleeve32. An elastomeric material is positioned inside the outer metal sleeve32of the bushing assembly10. The elastic material extends annularly about the one-piece bar pin36and the resiliency of the elastic material allows the one-piece bar pin36to move to a limited extent/degree within and relative to the outer metal sleeve32. The one-piece bar pin36has opposing ends38,40that are provided with holes for receiving fasteners42, such as bolts, that fixably attach the one-piece bar pin36to the frame bracket30.

The rear leaf spring end28may be connected to an air spring44that mounts to the frame via another bracket46. The vehicle suspension system22further includes a shock absorber48that mounts to the vehicle chassis at one end and a yoke49provided on the leaf spring24at an opposite end. The vehicle axle (not shown) is mounted to the leaf spring24by a shackle assembly50and is configured to support a pair of wheel assemblies (not shown) on opposite ends of the axle. The air spring44supports the load for the sprung mass of the vehicle and the shock absorber48dampens the movement of the vehicle axle and wheel assemblies relative to the frame. The bushing assembly10allows the front leaf spring end26to move relative to the frame bracket30to a limited (i.e., small) extent/degree, which reduces the noise, vibration, and harshness (NVH) transferred from the leaf spring24to the frame bracket30or in other words from the vehicle axle to the frame, which helps to isolate the sprung mass of the vehicle from shock and vibration.

However, one problem with current one-piece bar pins36, particularly in truck and off highway applications, is that they are heavy, expensive, and there is no economical way to remove the unnecessary excess material at the center of the bar pin36using conventional manufacturing processes. Typical one-piece bar pins36are machined as a single piece or are forged as a single piece. With machining, for example, it is typical to start with a solid bar that has a starting diameter that is greater than or equal to the largest diameter of the finished bar pin36and a starting length that is slightly greater than or equal to the finished bar pin36. A machining process is then used to machine away the unneeded material to form features such as flats, holes, flanges or other profile features of the bar pin36, resulting in a lot of excess scrap material (e.g., machining chips) being generated and lost to waste. All this excess material must be accounted for in the price of the finished part. In addition, there is no economical method to remove excess material from the center of a one-piece bar pin36since it is inaccessible to typical machining and boring operations, so the excess material is a penalty to both part weight as well as part cost.

While the vehicle suspension system22illustrated inFIG.1has only one bushing assembly10positioned at the connection between the front leaf spring end26and the frame bracket30, this configuration could be reversed where the bushing assembly10is alternatively attached to the rear leaf spring end28. It should also be appreciated that it is within the scope of the present disclosure to utilize any number of the bushing assemblies disclosed herein between any two components that require one of the components to pivot with respect to the other component. In addition, while the vehicle suspension system22illustrated inFIG.1has a leaf-spring configuration, it is within the scope of the present disclosure to utilize the bushing assemblies described herein in other types of vehicle suspension systems, including, without limitation, in independent suspension systems.

FIGS.2-5illustrate a bushing assembly20that has been constructed in accordance with the subject disclosure, which includes a two-piece bar pin assembly134. The bushing assembly20in the illustrated example includes an inner sleeve60, an intermediate sleeve/rate plate64, a bushing66, and an outer sleeve68. The inner sleeve60extends longitudinally between a first inner sleeve end70and a second inner sleeve end72. The inner sleeve60also has an inner sleeve outside surface78and an inner sleeve inside surface80, opposite the inner sleeve outside surface78, that defines a longitudinal bore82. The longitudinal bore82extends co-axially within the inner sleeve60along a longitudinal axis84. It should be understood that the terms “longitudinal” and “longitudinally” used in this disclosure describe elements that are generally arranged or directed in a direction that is parallel to the longitudinal axis84. It should also be appreciated that the inner sleeve60may have a variety of different shapes and configurations and may be made from a variety of different materials, all of which are considered to be within the scope of the subject disclosure. By way of example and without limitation, the inner sleeve60may have a cylindrical shape and may be made of metal.

The outer sleeve68of the bushing assembly20extends longitudinally between a first outer sleeve end112and a second outer sleeve end114. Optionally, the second outer sleeve end114may have an inwardly directed flange116that extends radially inward over at least part of the bushing66and towards the longitudinal axis84, while the first outer sleeve end112may have an outwardly directed flange118that extends radially outward away from the longitudinal axis84. The outer sleeve68has an outer sleeve outside surface120and an outer sleeve inside surface122opposite the outer sleeve outside surface120. The outer sleeve68and the inner sleeve60are concentrically arranged about the longitudinal axis84such that the outer sleeve68extends annularly about the inner sleeve60in a radially spaced relationship. Accordingly, the outer sleeve inside surface122faces the inner sleeve outside surface78and is radially spaced from the inner sleeve outside surface78. It should be appreciated that the outer sleeve68may have a variety of different shapes and configurations and may be made from a variety of different materials, all of which are considered to be within the scope of the subject disclosure. By way of example and without limitation, the outer sleeve68may have a cylindrical shape and may be made of metal.

The bushing66extends annularly between the inner and outer sleeves60,68and is disposed radially between the outer sleeve68and the inner sleeve60such that at least a portion of the outside bushing surface130abuts the outer sleeve inside surface122and at least a portion of the inside bushing surface132abuts the inner sleeve outside surface78. Preferably, the bushing66is molded or overmolded between the outer sleeve68and the inner sleeve60, however, other manufacturing processes may be used to form the bushing66. In operation, the bushing66mechanically decouples the inner sleeve60from the outer sleeve68. It should be appreciated that the bushing66may have a variety of different shapes and configurations and may be made from a variety of different materials, all of which are considered to be within the scope of the subject disclosure. Notwithstanding, the bushing66must be made in a configuration and a material that is resilient and capable of deflecting and dampening vibrations. By way of example and without limitation, the bushing66may be made of an elastomeric material such as natural rubber.

The rate plate64shown in the illustrated example is embedded in the resilient material of the bushing66to increase its effective stiffness and damping rate and is an optional component of the bushing assembly20. When present, the rate plate64extends annularly about the inner sleeve60in a concentric arrangement such that the rate plate64is spaced radially outward of the inner sleeve60. However, it should be appreciated that the rate plate64may have a variety of different shapes and configurations and may be made from a variety of different materials, all of which are considered to be within the scope of the subject disclosure. By way of example and without limitation, the rate plate64may have a cylindrical shape and may be made of metal. As noted above and shown in the second embodiment, it should also be appreciated that for at least some applications, the rate plate64may be eliminated entirely.

In accordance with the present disclosure, the bushing assembly20includes a two-piece bar pin assembly134. The two-piece bar pin assembly134is comprised of a first bar pin component136and a second bar pin component138. The first bar pin component136extends longitudinally between a first inboard end140and a first outboard end142. Similarly, the second bar pin component138extends longitudinally between a second inboard end144and a second outboard end146. The bushing assembly20is assembled such that the first and second inboard ends140,144of the first and second bar pin components136,138are received in the longitudinal bore82of the inner sleeve60in a press fit and are arranged such that the first and second inboard ends140,144of the first and second bar pin components136,138abut one another.

The first inboard end140of the first bar pin component136includes a first closed end bore148and the second inboard end144of the second bar pin component138includes a second closed end bore150. It should be appreciated by this description and terminology that the first closed end bore148extends longitudinally within the first bar pin component136and includes an open end152at the first inboard end140of the first bar pin component136and a closed end154that is located inside the first bar pin component136. Similarly, it should be appreciated that the second closed end bore150extends longitudinally within the second bar pin component138and includes an open end156at the second inboard end144of the second bar pin component138and a closed end158that is located inside the second bar pin component136. Further, because the first and second inboard ends140,144of the first and second bar pin components136,138are disposed inside the inner sleeve60in an abutting arrangement, the first closed end bore148and the second closed end bore150cooperate to form a closed cavity160within the two-piece bar pin assembly134.

The two-piece bar pin assembly134has an overall length162that is measured parallel to the longitudinal axis84, while the closed cavity160that is formed by the first and second closed end bores148,150has a longitudinal extent164that is measured parallel to the longitudinal axis84between the two opposing closed ends154,158of the closed cavity160. As such, the longitudinal extent164of the closed cavity160is less than the overall length162of the two-piece bar pin assembly134. Thus, it should be appreciated that the closed cavity160extends longitudinally within the two-piece bar pin assembly134, but does not extend completely through the first and second bar pin components136,138. It should also be appreciated that alternative arrangements are possible where only one of the first and second bar pin components136,138has a closed end bore forming the closed cavity160. While the first and second bar pin components136,138in the illustrated examples are mirror images of one another, extend across approximately half of the overall length162of the two-piece bar pin assembly134, and are interchangeable, it should be appreciated that other configurations are possible where one of the first and second bar pin components136,138is longer than the other.

The first and second bar pin components136,138may optionally include one or more clocking, interlocking, and/or alignment features to facilitate the proper assembly of the bushing assembly20. In the illustrated example, the first inboard end140of the first bar pin component136includes a first projection166athat is aligned with and received in a first opposing recess168ain the second inboard end144of the second bar pin component138. The second inboard end144of the second bar pin component138includes a second projection166bthat is aligned with and received in a second opposing recess168bin the first inboard end140of the first bar pin component136. The first projection166aand the first opposing recess168aare diametrically opposed (i.e., positioned 180 degrees apart) relative to the second projection166band the second opposing recess168band provide an interlocking arrangement between the first and second bar pin components136,138that ensures proper alignment of the first and second bar pin components136,138when they are pressed into the longitudinal bore82of the inner sleeve60. The first projection166aand the first opposing recess168aand the second projection166band the second opposing recess168balso prevent the first bar pin component136from rotating relative to the second bar pin component138within the longitudinal bore82of the inner sleeve60.

Although other geometries are possible, in the illustrated examples, the first and second outboard ends142,146of the first and second bar pin components136,138have a rectangular shape with a pair of flattened surfaces170a,170b. Meanwhile, each of the first and second inboard ends140,144of the first and second bar pin components136,138has a cylindrical shape that extends to a radially projecting flange172a,172b. The radially projecting flange172aon the first bar pin component136abuts the first inner sleeve end70and therefore acts as a stop when the first bar pin component136is pressed into the longitudinal bore82of the inner sleeve60. Similarly, the radially projecting flange172bon the second bar pin component138abuts the second inner sleeve end72and therefore acts as a stop when the second bar pin component138is pressed into the longitudinal bore82of the inner sleeve60.

The first outboard end142of the first bar pin component136has a first through bore174athat is transverse (i.e., arranged at a perpendicular or oblique angle) to the longitudinal axis84and the second outboard end146of the second bar pin component138has a second through bore174bthat is also transverse to the longitudinal axis84. The first and second through bores174a,174bextend entirely through the first and second outboard ends142,146of the first and second bar pin components136,138from one flattened surface170ato the other flattened surface170band are configured to receive the fasteners42shown inFIG.1.

Optionally, the first and second outboard ends142,146of the first and second bar pin components136,138have peripheral surfaces176a,176bthat are concave (i.e., have a concave chamfer). Preferably, the first and second bar pin components136,138are made of metal and have compacted areas of greater density formed by a cold forming/cold working process (e.g., a cold heading process).

FIGS.6-9illustrate another embodiment of an exemplary bushing assembly20′, which is a simplified version of the bushing assembly20illustrated inFIGS.2-5. Thus, the elements of the bushing assembly20′ shown inFIGS.6-9are the same or substantially the same as the bushing assembly20shown inFIGS.2-5, except that the rate plate64has been eliminated inFIGS.6-9. In addition, the geometries of the peripheral surfaces176a,176b, the first and second projections166a,166b, and the first and second opposing recesses168a,168bhave been simplified inFIGS.6-9to reduce cost and improve manufacturability using a cold heading process. Because the elements of the bushing assembly20′ shown inFIGS.6-9are the same or substantially the same as the bushing assembly20shown inFIGS.2-5, the corresponding elements inFIGS.6-9are identified with the same reference numbers used inFIGS.2-5, but have a prime symbol (′) appended after the reference number. Thus, it should be appreciated that the above description applies equally to the elements shown inFIGS.6-9and will not be repeated unnecessarily.

It should be appreciated thatFIGS.2-5andFIGS.6-9illustrate bushing assemblies20,20′ in a pre-installed and fully assembled state. To install either bushing assembly20,20′, the outer sleeve68,68′ is pressed into the loop34at the front leaf spring end26of one of the leaf springs24shown inFIG.1. Fasteners42are then inserted into the first and second through bores174a,174b,174a′,174b′ in the first and second outboard ends142,146,142′,146′ of the first and second bar pin components136,138,136′,138′ and are threaded into the frame bracket30or are secured by nuts to fixably couple the first and second bar pin components136,138,136′,138′ to the frame bracket30.

A method of assembling the bushing assemblies20,20′ discussed above will now be described. The method includes the step of arranging the outer sleeve68,68′ concentrically/annularly about the inner sleeve60,60′ such that the outer sleeve68,68′ and the inner sleeve60,60′ are radially spaced from one another and are co-axially aligned about the longitudinal axis84,84′. The method proceeds with the step of molding the bushing66,66′ of elastomeric material between the outer sleeve68,68′ and the inner sleeve64,64′. The method further includes the step of forming the two-piece bar pin134,134′ by individually forming the first and second bar pin components136,138,136′,138′. This step includes forming the first bar pin component136,136′ with a first inboard end140,140′ and a first outboard end142,142′ and forming the second bar pin component138,138′ with a second inboard end144,144′ and a second outboard end146,146′. Preferably, the step of forming a two-piece bar pin134includes cold forming/cold working the first and second bar pin components136,138. For example, a cold heading process may be used to form the first and second bar pin components136,138,136′,138′. This allows the features and geometry of the first and second bar pin components136,138,136′,138′ to be formed without the removal of material, like a machining process would, which generates scrap. Thus, the innovation of utilizing a two-piece bar pin134,134′ instead of a one-piece bar pin36allows the bar pin to be made using a cold forming/cold working process instead of a machining process, which can reduce feedstock costs (i.e., the cost of materials) and enables the formation of one or more closed cavities160,160′, concave chamfers176a,176b, or other weight saving features without the removal of feedstock material and without compromising strength. For example, the method may include the steps of forming a first closed end bore148,148′ in the first inboard end140,140′ of the first bar pin component136,136′, forming a second closed end bore150,150′ in the second inboard end144,144′ of the second bar pin component138,138′, and forming concave chamfers/peripheral surfaces176a,176bon the first and second outboard ends142,146of the first and second bar pin components136,138. The method may also include forming attachment features such as forming a pair of flattened surfaces170a,170b,170a′,170b′ on the first and second outboard ends142,146,142′,146′ of the first and second bar pin components136,138,136′,138′. All of these manufacturing/forming steps may be performed using a cold forming/working process, such as cold heading, or a hot forming/hot working process, such as hot forging, because the bar pin134,134′ is a two-piece assembly.

Finally, the method may proceed with the step of drilling or machining first and second through bores174a,174b,174a′,174b′ in the first and second outboard ends142,146,142′,146′ of the first and second bar pin components136,138,136′,138′.

The innovation of utilizing a two-piece bar pin134,134′ also allows the cold forming of alignment features. For example, the method may include the steps of forming a first projection166a,166a′ on the first inboard end140,140′ of the first bar pin component136,136′, forming a first opposing recess168a,168a′ in the second inboard end144,144′ of the second bar pin component138,138′, forming a second projection166b,166b′ on the second inboard end144,144′ of the second bar pin component138,138′, and/or forming a second opposing recess168b,168b′ in the first inboard end140,140′ of the first bar pin component136,136′.

After the first and second bar pin components136,138,136′,138′ are formed, the method continues with the step of pressing the first inboard end140,140′ of the first bar pin component136,136′ into the first inner sleeve end70,70′ and pressing the second inboard end144,144′ of the second bar pin component138,138′ into the second inner sleeve end72,72′ until the first and second inboard ends140,144,140′,144′ of the first and second bar pin components136,138,136′,138′ abut one another inside the longitudinal bore82,82′ of the inner sleeve60,60′. The method may further include the step of arranging the first and second inboard ends140,144,140′,144′ of the first and second bar pin components136,138,136′,138′ inside the longitudinal bore82,82′ of the inner sleeve60,60′ such that the first closed end bore148,148′ and the second closed end bore150,150′ cooperate to form a closed cavity160,160′ within the two-piece bar pin134,134′. In embodiments where the first and second bar pin components136,138,136′,138′ include alignment features, the method may further include the steps of aligning the one or more projections166a,166b,166a′,166b′ on the first and second inboard ends140,144,140′,144′ of the first and second bar pin components136,138,136′,138′ with one or more opposing recesses168a,168b,168a′,168b′ in the first and second inboard ends140,144,140′,144′ of the first and second bar pin components136,138,136′,138′ and pressing the first inboard end140,140′ of the first bar pin component136,136′ and the second inboard end144,144′ of the second bar pin component138,138′ into the longitudinal bore82,82′ of the inner sleeve60,60′ until the first projection166a,166a′ on the first inboard end140,140′ of the first bar pin component136,136′ is received in the first opposing recess168a,168a′ in the second inboard end144,144′ of the second bar pin component138,138′ and the second projection166b,166b′ on the second inboard end144,144′ of the second bar pin component138,138′ is received in the second opposing recess168b,168b′ in the first inboard end140,140′ of the first bar pin component136,136′ to interlock the first bar pin component136,136′ with the second bar pin component138,138′.

The method further includes the steps of installing the bushing assembly20,20′ in a vehicle suspension system22. This method includes the step of pressing the outer sleeve68,68′ into the loop34at the front leaf spring end26of one of the leaf springs24shown inFIG.1. The method proceeds with the step of inserting fasteners42into the first and second through bores174a,174b,174a′,174b′ in the first and second outboard ends142,146,142′,146′ of the first and second bar pin components136,138,136′,138′ and the frame bracket30to fixably couple the first and second bar pin components136,138,136′,138′ to the frame bracket30. In accordance with this step, the fasteners42may be threaded directly into the frame bracket30, or alternatively, this step of the method may include threading nuts onto the shaft of the fasteners42and tightening the nuts to fixably couple the first and second bar pin components136,138,136′,138′ to the frame bracket30.

Advantageously, the two-piece bar pin assemblies134,134′ described herein can be made by starting with a slug of material that has the same weight or almost the same weight as the finished part, with little to no scrap cost lost to machining. In addition, the design of the two-piece bar pin assemblies134,134′ described herein provides access to the center of the bar pin134,134′ so that it can be hollowed out, providing the ability to eliminate unnecessary material in the center of the bar pin134,134′ that cannot be eliminated with conventional processes. The closed cavity160,160′ in the center on the two-piece bar pin assemblies134,134′ allows for the starting slug to be made with significantly less material allowing for the potential to significantly lower cost and weight. The design of the two-piece bar pin assemblies134,134′ described herein also makes it easier/more economical to create a bar pin134,134′ where the center of the bar pin134,134′ is smaller in diameter than the outboard ends142,146,142′,146′. With convention forming processes, it is very difficult, if not impossible to economically form the complex shapes of the bar pin134,134′ using a single piece of feedstock because the plane that the forming dies move in does not allow for it. With conventional machining process, the machining of such shapes would result in significant cost increases due to the amount of scrap generated and therefore lost to the machining process.

Many modifications and variations of the present disclosure are possible in light of the above teachings and may be practiced otherwise than as specifically described while within the scope of the appended claims. These antecedent recitations should be interpreted to cover any combination in which the inventive novelty exercises its utility. With respect to the methods set forth herein, the order of the steps may depart from the order in which they appear without departing from the scope of the present disclosure and the appended method claims. Additionally, various steps of the method may be performed sequentially or simultaneously in time.