Patent Publication Number: US-2022234663-A1

Title: Modular front drivetrain assembly

Description:
PRIORITY 
     This application is a continuation-in-part of, and claims the benefit of, U.S. patent application, entitled “Modular Front Drivetrain Assembly,” filed on Sep. 14, 2020, and having application Ser. No. 17/019,829, which claims the benefit of, and priority to, U.S. Provisional Application, filed on Sep. 14, 2019, and having application Ser. No. 62/900,481. This application also claims the benefit of, and priority to, U.S. Provisional Application, entitled “Front Structural Bulkhead For Vehicle Chassis”, filed on Mar. 22, 2021, and having application Ser. No. 63/164,079. The entirety of each of the aforementioned applications are incorporated herein by reference. 
    
    
     FIELD 
     Embodiments of the present disclosure generally relate to the field of vehicle drivetrains. More specifically, embodiments of the disclosure relate to an apparatus and methods for a modular front drivetrain comprising a single assembly that may be installed onto and removed from a vehicle. 
     BACKGROUND 
     A double wishbone suspension is a well-known independent suspension design using upper and lower wishbone-shaped arms to operably couple a front wheel of a vehicle. Typically, the upper and lower wishbones or suspension arms each has two mounting points to a chassis of the vehicle and one mounting joint at a spindle assembly or knuckle. A shock absorber and a coil spring may be mounted onto the wishbone to control vertical movement of the front wheel. The double wishbone suspension facilitates control of wheel motion throughout suspension travel, including controlling such parameters as camber angle, caster angle, toe pattern, roll center height, scrub radius, scuff, and the like. 
     Double wishbone suspensions may be used in a wide variety of vehicles, including heavy-duty vehicles, as well as many off-road vehicles, as shown in  FIG. 1 .  FIG. 1  shows an off-road vehicle  100  that is of a Side-by-Side variety. The Side-by-Side is a four-wheel drive off-road vehicle that typically seats between two and six occupants and is sometimes referred to as a Utility Task Vehicle (UTV), a Recreational Off-Highway Vehicle (ROV), or a Multipurpose Off-Highway Utility Vehicle (MOHUV). In addition to the side-by-side seating arrangement, many UTVs have seat belts and roll-over protection, and some may have a cargo box at the rear of the vehicle. A majority of UTVs come factory equipped with hard tops, windshields, and cab enclosures. 
     The double-wishbone suspension often is referred to as “double A-arms,” although the arms may be A-shaped, L-shaped, J-shaped, or even a single bar linkage. In some embodiments, the upper arm may be shorter than the lower arm so as to induce negative camber as the suspension jounces (rises). Preferably, during turning of the vehicle, body roll imparts positive camber gain to the lightly loaded inside wheel, while the heavily loaded outer wheel gains negative camber. 
     The spindle assembly, or knuckle, is coupled between the outboard ends of the upper and lower suspension arms. In some designs, the knuckle contains a kingpin that facilitates horizontal radial movement of the wheel, and rubber or trunnion bushings for vertical hinged movement of the wheel. In some relatively newer designs, a ball joint may be disposed at each outboard end to allow for vertical and radial movement of the wheel. A bearing hub, or a spindle to which wheel bearings may be mounted, may be coupled with the center of the knuckle. 
     Constant velocity (CV) joints allow pivoting of the suspension arms and the spindle assembly, while a drive shaft coupled to the CV joint delivers power from a transaxle to the wheels. Although CV joints are typically used in front wheel drive vehicles, off-road vehicles such as four-wheeled buggies comprise CV joints at all wheels. Constant velocity joints typically are protected by a rubber boot and filled with molybdenum disulfide grease. 
     Given that off-road vehicles routinely travel over very rough terrain, such as mountainous regions, there is a desire to improve the mechanical strength and performance of off-road drivetrain and suspension systems, while at the same reducing the mechanical complexity of such systems. 
     SUMMARY 
     An apparatus and methods are provided for a modular front drivetrain comprising a single assembly that may be installed onto and removed from a vehicle. The modular front drivetrain comprises a modular chassis supporting a transaxle, a front differential, and a steering gear for operating front wheels of the vehicle. The transaxle and front differential are configured to convey torque from an engine onboard the vehicle to the front wheels. A spindle assembly is coupled with each front wheel of the vehicle and pivotally joined with the modular chassis by way of a front suspension system. A drive axle is engaged with the front differential and each spindle assembly for conveying torque to the front wheels. Steering rods coupled with the spindle assemblies are configured for horizontally rotating the front wheels according to operation of a steering wheel onboard the vehicle. The modular front drivetrain is configured to facilitate a practitioner replacing an entire drivetrain and suspension quickly and easily in the event of a part failure. 
     In an exemplary embodiment, a modular front drivetrain for operating front wheels of a vehicle comprises: a modular chassis supporting a drivetrain and a steering system operatively coupled with the front wheels; a spindle assembly coupled with each front wheel; and a front suspension system coupling each spindle assembly to the modular chassis. 
     In another exemplary embodiment, the modular front drivetrain comprises a single drivetrain and suspension assembly that is configured to be installed onto and removed from the vehicle. In another exemplary embodiment, the modular front drivetrain is configured to facilitate a practitioner replacing an entire drivetrain and suspension quickly and easily in the event of a part failure. 
     In another exemplary embodiment, the front suspension system includes an upper control arm and a lower control arm that are configured to couple the front wheel with the modular chassis. In another exemplary embodiment, the upper control arm comprises two inboard upper control arm joints that couple the upper control arm to the modular chassis and an outboard upper control arm joint that couples the upper control arm to the spindle assembly. In another exemplary embodiment, the lower control arm includes two inboard lower control arm joints that couple the lower control arm to the modular chassis and an outboard lower control arm joint that couples the lower control arm to the spindle assembly. In another exemplary embodiment, the upper control arm and the lower control arm are configured to facilitate vertical motion of the front wheel during travel over terrain and accommodate horizontal motion of the front wheel during steering of the front wheel by way of the steering gear. In another exemplary embodiment, a strut that is comprised of a shock absorber and a coil spring is mounted to the lower control arm by way of a lower pivot; and wherein a top of the strut is coupled to an upper pivot disposed on a chassis of the vehicle. 
     In another exemplary embodiment, the drivetrain includes a transaxle, a front differential and a drive axle coupled between each front wheel and the front differential. In another exemplary embodiment, the drive axle is configured to conduct torque from the transaxle to the front wheel and accommodate vertical pivoting motion of the front suspension system in response to road conditions. In another exemplary embodiment, the drive axle includes a constant velocity joint that is coupled with the spindle assembly and configured to allow uninterrupted torque transmission from the transaxle to the front wheel during vertical pivoting of the front suspension assembly due to road conditions. 
     In another exemplary embodiment, the steering system includes a steering rod coupled between each spindle assembly and a steering gear disposed on the modular chassis. In another exemplary embodiment, the steering gear is configured to cause the front wheels to articulate horizontally with respect to the modular chassis upon the steering gear being turned by way of a steering wheel of the vehicle. In another exemplary embodiment, the steering rod is coupled with each spindle assembly by way of a steering rod-end joint configured to allow vertical and horizontal rotational motion of the spindle assembly during operation of the vehicle. In another exemplary embodiment, the steering rod-end joint is coupled with each spindle assembly forward of a drive axle so as to provide a leading-edge steering system to the vehicle. 
     In an exemplary embodiment, a method for a modular front drivetrain for operating front wheels of a vehicle comprises: configuring a modular chassis for supporting a drivetrain to convey torque from an engine onboard the vehicle to the front wheels; coupling each front wheel to the modular chassis by way of a spindle assembly and a front suspension system; communicating torque from the drivetrain to the front wheel by way of a front differential and drive axles; coupling a braking system with the drive axles for slowing rotation of the front wheels; disposing a steering system on the modular chassis for directing horizontal motion of the front wheels; and installing the modular front drivetrain onto the vehicle. 
     In another exemplary embodiment, the method further comprises configuring the modular front drivetrain as a single drivetrain and suspension assembly to be installed onto and removed from the vehicle. In another exemplary embodiment, coupling includes configuring the front suspension system to allow vertical motion of the front wheels due to road conditions. In another exemplary embodiment, disposing includes coupling a steering rod between each spindle assembly and a steering gear disposed on the modular chassis. In another exemplary embodiment, coupling the steering rod includes coupling a steering rod-end joint with each spindle assembly forward of the drive axles to provide a leading-edge steering system to the vehicle. In another exemplary embodiment, communicating torque includes coupling each drive axle with the spindle assembly by way of a constant velocity joint configured to allow uninterrupted torque transmission from the transaxle to the front wheel during vertical pivoting of the front suspension assembly due to road conditions. 
     In an exemplary embodiment, a front structural bulkhead for an off-road vehicle comprises: a modular chassis for supporting drivetrain components that are operably coupled with front wheels of the vehicle; upper mounting points for coupling with upper control arms comprising a front suspension; lower mounting points for coupling with lower control arms comprising the front suspension; and a steering gear for steering the front wheels. 
     In another exemplary embodiment, the drivetrain components include any one or more of a transaxle, a front differential, a steering gear, a braking system, and the like. In another exemplary embodiment, the steering gear is coupled with steering rods such that turning the steering gear by way of a steering wheel of the vehicle causes the front wheels to articulate horizontally. In another exemplary embodiment, the upper mounting points and the lower mounting points are configured to allow the front wheels to move vertically due to the vehicle traveling over terrain. 
     In another exemplary embodiment, the upper mounting points are configured to receive inboard joints comprising upper control arms. In another exemplary embodiment, the lower mounting points are configured to receive inboard joints comprising lower control arms. 
     These and other features of the concepts provided herein may be better understood with reference to the drawings, description, and appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings refer to embodiments of the present disclosure in which: 
         FIG. 1  illustrates an exemplary embodiment of an off-road vehicle that is particularly suitable for implementation of a modular front drivetrain in accordance with the present disclosure; 
         FIG. 2  illustrates an upper perspective view of a driver-side portion of an exemplary embodiment of a modular front drivetrain; 
         FIG. 3  illustrates a front view of the modular front drivetrain of  FIG. 2 ; 
         FIG. 4  illustrates an upper perspective view of a driver-side portion of an exemplary embodiment of a modular front drivetrain; 
         FIG. 5  illustrates an exemplary embodiment of an off-road vehicle that is configured to seat up to four occupants and includes a front structural bulkhead in accordance with the present disclosure; 
         FIG. 6  illustrates an exemplary embodiment of an off-road vehicle that includes a front structural bulkhead in accordance with the present disclosure; 
         FIG. 7  illustrates an isometric view of an exemplary embodiment of vehicle chassis that includes a front structural bulkhead according to the present disclosure; 
         FIG. 8  illustrates a top plan view of the vehicle chassis of  FIG. 7 , in accordance with the present disclosure; 
         FIG. 9  illustrates a side plan view of the vehicle chassis of  FIG. 8  according to the present disclosure; 
         FIG. 10  illustrates a front view of the vehicle chassis of  FIG. 8 , showing a front structural bulkhead coupled with the vehicle chassis, in accordance with the present disclosure; 
         FIG. 11  illustrates a perspective view of an exemplary embodiment of a front structural bulkhead that may be incorporated into an off-road vehicle in accordance with the present disclosure; and 
         FIG. 12  illustrates a close-up view of an exemplary embodiment of a front structural bulkhead incorporated into an off-road vehicle, according to the present disclosure. 
     
    
    
     While the present disclosure is subject to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. The present disclosure should be understood to not be limited to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure. 
     DETAILED DESCRIPTION 
     In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be apparent, however, to one of ordinary skill in the art that the modular front drivetrain and methods disclosed herein may be practiced without these specific details. In other instances, specific numeric references such as “first joint,” may be made. However, the specific numeric reference should not be interpreted as a literal sequential order but rather interpreted that the “first joint” is different than a “second joint.” Thus, the specific details set forth are merely exemplary. The specific details may be varied from and still be contemplated to be within the spirit and scope of the present disclosure. The term “coupled” is defined as meaning connected either directly to the component or indirectly to the component through another component. Further, as used herein, the terms “about,” “approximately,” or “substantially” for any numerical values or ranges indicate a suitable dimensional tolerance that allows the part or collection of components to function for its intended purpose as described herein. 
     A double wishbone suspension generally comprises upper and lower suspension arms that operably couple a front wheel of a vehicle. The upper and lower suspension arms each typically include two mounting points to a chassis of the vehicle and one mounting joint at a spindle assembly. The spindle assembly is coupled between the outboard ends of the upper and lower suspension arms and is configured to allow vertical and horizontal radial movement of a wheel coupled with the spindle assembly. Constant velocity (CV) joints allow pivoting of the suspension arms and the spindle assembly, while a drive shaft coupled to the CV joint conveys power from a transaxle to the wheel. Given that off-road vehicles routinely travel over very rough terrain, such as mountainous regions, there is a desire to improve the mechanical strength and performance of off-road drivetrain and suspension systems, while at the same reducing the mechanical complexity of such systems. Embodiments of the disclosure provide to a modular front drivetrain comprising a single assembly that may be installed onto and removed from a vehicle. 
       FIG. 1  shows an off-road vehicle  100  that is particularly suitable for implementation of a modular front drivetrain in accordance with the present disclosure. As disclosed hereinabove, the off-road vehicle  100  generally is of a Utility Task Vehicle (UTV) variety that seats two occupants, includes a roll-over protection system  104 , and may have a cab enclosure  108 . Rear wheels  112  of the off-road vehicle  100  may be operably coupled with a chassis  116  by way of a trailing arm suspension system. Front wheels  120  may be operably coupled with the chassis  116  by way of a front suspension system and a spindle assembly. It should be understood, however, that the modular front drivetrain disclosed herein is not to be limited to the off-road vehicle  100 , but rather the modular front drivetrain may be incorporated into a wide variety of vehicles, other than UTVs, without limitation. 
       FIG. 2  illustrates an upper perspective view of a driver-side portion of an exemplary embodiment of a modular front drivetrain  124  that may be implemented in the off-road vehicle  100 . The modular front drivetrain  124  includes a modular chassis  128  that supports a transaxle  132 , a front differential  136 , and a steering gear  140  that are operably coupled with a spindle assembly  144  and the front wheel  120  by way of a front suspension system  148 . Further, the modular chassis  128  provides mounting points for the front suspension  148 , in lieu of conventional mounting points that comprise portions of the chassis  116  of the vehicle. It is to be understood, therefore, that the modular front drivetrain  124  comprises a single drivetrain/suspension assembly that may be installed onto and removed from the vehicle  100 , unlike a conventional drivetrain and suspension that comprise multiple components that must be individually assembled onto the chassis  116  of the vehicle. 
     The front suspension system  148  includes an upper control arm (UCA)  152  and a lower control arm (LCA)  156  that couple the front wheel  120  with the modular chassis  128 . The UCA  152  comprises two inboard UCA joints  160  that couple the UCA  152  to the modular chassis  128  and an outboard UCA joint  164  that couples the UCA  152  to the spindle assembly  144 . As best shown in  FIG. 3 , the LCA  156  includes two inboard LCA joints  168  that couple the LCA  156  to the modular chassis  128  and an outboard LCA joint  172  that couples the LCA  156  to the spindle assembly  144 . As will be recognized, the UCA and LCA  152 ,  156  generally are of a double wishbone variety of suspension that facilitates vertical motion of the front wheel  120  during travel over terrain, as well as facilitating horizontal motion of the front wheel  120  during steering of the vehicle  100  by way of the steering gear  140 . The UCA and LCA  152 ,  156  further facilitate controlling various parameters affecting the orientation of the front wheel  120  with respect to the off-road vehicle  100 , such as, by way of non-limiting example, camber angle, caster angle, toe pattern, roll center height, scrub radius, and scrub. 
     It should be understood that although the front suspension system  148  is disclosed specifically in connection with the driver-side of the off-road vehicle  100 , a passenger-side front suspension system is to be coupled with a passenger side of the modular chassis  128 . It should be further understood that the passenger-side front suspension system is substantially identical to the driver-side front suspension system  148 , with the exception that the passenger-side front suspension system is configured specifically to operate with the passenger-side of the modular chassis  128 . As will be appreciated, therefore, the passenger-side front suspension system and the driver-side front suspension system  148  may be configured as reflections of one another across a longitudinal midline of the off-road vehicle  100 . 
     As shown in  FIGS. 2-3 , a strut  176  that is comprised of a shock absorber and a coil spring is mounted to the LCA  156  by way of a lower pivot (not shown). A top of the strut  176  is coupled to an upper pivot (not shown) that may be disposed on the chassis  116  of the vehicle  100 . The strut  176  is configured to dampen vertical motion of the front suspension system  148  due to movement of the front wheel  120  as the vehicle  100  travels over terrain. The UCA  152  may be suitably configured, such as in the form of a J-arm, so as to facilitate coupling the strut  176  between the LCA  156  and the chassis  116  (see  FIG. 1 ) of the vehicle  100  in lieu of being coupled between the UCA  152  and the chassis  116 . Moreover, it is contemplated that in some embodiments, the strut  176  may be coupled between the LCA  156  and the modular chassis  128 , without limitation, and without deviating beyond the scope of the present disclosure. 
     As best shown in  FIG. 2 , a drive axle  180  is coupled between the front wheel  120  and the front differential and transaxle  136 ,  132 . The drive axle  180  is configured to conduct torque from the transaxle  132  to the front wheel  120  and accommodate vertical pivoting motion of the front suspension system  148  in response to road conditions, as is straightforward to see upon comparing  FIG. 3  and  FIG. 4 . As best shown in  FIG. 3 , the drive axle  180  includes a constant velocity (CV) joint  184  that is coupled with the spindle assembly  144 . The CV joint  184  enables uninterrupted torque transmission from the transaxle  132  to the front wheel  120  during vertical pivoting of the front suspension assembly  148  due to road conditions. 
     In the embodiment illustrated in  FIGS. 2-3 , a steering rod  188  couples the spindle assembly  144  with the steering gear  140  disposed on the modular chassis  128 . The steering rod  188  may be coupled with the spindle assembly  144  by way of a steering rod-end joint  192  that is similar to the inboard UCA joints  160 . It is contemplated, therefore, that the steering rod-end joint  192  may be of a Heim-joint variety or may be of a bushing variety, as desired. As will be appreciated, the steering rod-end joint  192  allows vertical and horizontal rotational motion of the spindle assembly  144  during operation of the vehicle  100 . 
     Moreover, the steering rod-end joint  192  is coupled with the spindle assembly  144  forward of the drive axle  180 , thereby providing a leading-edge steering system to the vehicle  100 . Experimentation has demonstrated that the leading-edge steering system shown in  FIGS. 2-3  advantageously decreases leverage of the front wheel  120  on the steering rod-end joint  192  and the steering rod  188 , thereby substantially eliminating bump steer that may occur due to forces exerted on the front wheel  120  by rough terrain. Details pertaining to rod-end joints are disclosed in above-mentioned U.S. patent application Ser. No. 15/625,692, which is entitled “Rod-End Front Suspension.” Further, details pertaining to leading-edge steering systems are disclosed in U.S. patent application Ser. No. 15/625,813, entitled “Leading-Edge Steering Assembly,” filed on Jun. 16, 2017, the entirety of which is incorporated herein by reference. 
     Turning again to  FIG. 2 , the modular front drivetrain  124  may further include a braking system configured to enable a practitioner to slow the rotation rate of the front wheel  120  during operation of the vehicle  100 . In the illustrated embodiment of  FIGS. 2-3 , the brake system comprises a brake caliper  196  that is fastened onto the modular chassis  128 . A brake disc  200  is coupled to the drive axle  180  such that a periphery of the brake disc  200  passes within the brake caliper  196 . As will be recognized, when the practitioner depresses a brake pedal of the vehicle  100  the brake caliper  196  applies pressure to the brake disc  200 , thus slowing the rotation rate of the front wheel  120 . The brake caliper  196  may be cable operated or may be operated by way hydraulic lines. Although not shown in  FIGS. 2-3 , the brake disc  200  may be coupled with a hub comprising the front differential  136 . In some embodiments, however, the brake disc  200  may be coupled with a constant velocity joint that is coupled with the hub of the front differential  136 . It is contemplated that the brake caliper  196  and the brake disc  200  may be incorporated into the modular front drivetrain  124  in a wide variety of configurations, without limitation, and without deviating beyond the scope of the present disclosure. 
     As disclosed hereinabove, the modular front drivetrain  124  comprises a modular chassis  128  that supports the transaxle  132 , the front differential  136 , the drive axle  180  and the front suspension system  148 , such that engine torque applied to the transaxle  132  is conveyed to the front wheel  120 . The modular chassis  128  also supports the steering gear  140  and the steering rod  188 , such that turning the steering gear  140 , by way of a steering wheel of the vehicle  100 , causes the front wheel  120  to articulate horizontally with respect to the modular chassis  128 . Further, the modular chassis  128  provides mounting points for the front suspension  148  that allow the front wheel  120  to move vertically from a low position (e.g., due to “maximal bounce”), shown in  FIG. 3 , to a high position (e.g., due to “maximal bump”), shown in  FIG. 4 . As such, the modular front drivetrain  124  is not limited to the specific configuration shown in  FIGS. 2-3 , but rather the configuration of the modular front drivetrain  124  may be varied in accordance with the configuration of each of the components comprising the modular front drivetrain  124 , without limitation. 
     Moreover, the modular front drivetrain  124  generally may be varied in accordance with the specific type of vehicle  100  into which the modular front drivetrain  124  is to be implemented. It is contemplated that the modular front drivetrain  124  may be implemented in any of various off-road vehicles  100 , such as, by way of non-limiting example, Utility Task Vehicles (UTVs), Recreational Off-Highway Vehicles (ROVs), or Multipurpose Off-Highway Utility Vehicles (MOHUVs), without limitation. As such, the modular front drivetrain  124  is particularly well-suited for off-road racing applications, such as desert racing, short course racing, hill climbing, rallying, and the like. 
     In addition to the off-road applications discussed above, it is contemplated that, in some embodiments, the modular front drivetrain  124  may be incorporated into racing vehicles that are not necessarily intended for off-road racing. For example, the modular front drivetrain  124  may be incorporated into racing vehicles that may be used for any of formula racing, sports car racing, stock car racing, drag racing, touring car racing, production car racing, as well as amateur open-wheel racing applications, such as karting, and the like. In such applications, the modular front drivetrain  124  advantageously enables an entire drivetrain and suspension assembly to be quickly and easily replaced in the event of a part failure, unlike in the case of conventional racing vehicles that may be sidelined during a race due to the failure of an individual part comprising the drivetrain or the suspension. 
     In some embodiments, the strength and performance of an off-road vehicle chassis may be improved by implementing a front structural bulkhead. For example, in some embodiments, the chassis may be a welded-tube variety of chassis that includes a front portion and a rear portion that are joined to an intervening passenger cabin portion, wherein frontward stays and a bulkhead mount couple the front structural bulkhead to the front portion. Bulkhead mount pillars and a bulkhead mount crossmember may be used to couple the front structural bulkhead to the passenger cabin portion. In some embodiments, the front structural bulkhead includes a modular chassis for supporting drivetrain components that are operably coupled with front wheels of the vehicle. The front structural bulkhead may further include upper and lower mounting points configured to receive front suspension controls arms that allow the front wheels to move vertically due to the vehicle traveling over terrain. 
       FIG. 5  shows an exemplary embodiment of an off-road vehicle  300  that is particularly suitable for implementation of a front structural bulkhead in accordance with the present disclosure. The off-road vehicle  300  shown in  FIG. 5  generally is of a Utility Task Vehicle (UTV) variety that seats up to four occupants, includes a roll-over protection system  304 , and may have a cab enclosure  308 . Rear wheels  112  of the off-road vehicle  300  may be operably coupled with a chassis  116  by way of a trailing arm suspension system  320 . Front wheels  324  may be operably coupled with the chassis  116  by way of a front suspension system  328 . It should be understood, however, that the front structural bulkhead disclosed herein is not to be limited to the specific off-road vehicle  300  shown in  FIG. 5 , but rather the front structural bulkhead may be incorporated into a wide variety of vehicles, other than the off-road vehicle  300  of  FIG. 5 , without limitation. 
       FIG. 6  illustrates an exemplary embodiment of an off-road vehicle  300  that includes a front structural bulkhead  340  in accordance with the present disclosure. In the embodiment illustrated in  FIG. 6 , the cab enclosure  308  and other body panels are removed to reveal the chassis  116  and the front structural bulkhead  340  comprising the off-road vehicle  300 . The chassis  116  generally is a welded-tube variety of chassis that includes a front portion  328  and a rear portion  332  that are joined to an intervening passenger cabin portion  336 . The passenger cabin portion  336  shown in  FIG. 6  is configured to seat up to four occupants. A front canopy  344  and a rear canopy  348  are configured to impart structural integrity to the chassis  116  and to provide a roll-over protection system  304  to occupants of the off-road vehicle  300 . 
     The front portion  328  generally is configured to support various components comprising the off-road vehicle  300 , such as, by way of non-limiting example, the front suspension  328  and the front structural bulkhead  340 . The rear portion  332  is configured to support the rear suspension  320  of the off-road vehicle  300 , such as rear trailing arms, as well as support various drivetrain components, shown in  FIG. 5 , such as an engine, a transaxle, a rear differential, an engine, and the like. 
     As will be appreciated, the passenger cabin portion  336 , as well as the front and rear portions  328 ,  332 , are configured to distribute loading forces arising during operation of the vehicle  300  so as to resist damage to components comprising the vehicle  300  and to protect occupants riding within the vehicle  300 . To this end, the front canopy  344  and the rear canopy  348  that are configured to be coupled with the chassis  116 . More specifically, the front canopy  344  is configured to be coupled with the front portion  328 , and the rear canopy  348  is configured to be coupled with the rear portion  332 . Further, the front canopy  344  is configured to be coupled with the rear canopy  348 . It should be recognized, therefore, that the front canopy  344  and the rear canopy  348  are configured to contribute to the overall integrity of the entire chassis  116 . 
     As mentioned above, the front portion  328  generally supports various components comprising the off-road vehicle  300 , including the front suspension  328  and the front structural bulkhead  340 . As shown in  FIG. 7 , the front portion  328  may be defined by a front hoop  352  at a top of the front portion  328  and a bulkhead mount  356  at a bottom of the front portion  328 . Frontward stays  360  attach the front hoop  352  to the bulkhead mount  356 . The bulkhead mount  356  is configured to be coupled with the front structural bulkhead  340  (see  FIG. 6 ), which supports at least the front suspension  328  and includes a steering gear, a front differential, and the like. In some embodiments, the bulkhead mount  356  may be coupled with a modular front drivetrain that supports an entire front drivetrain and suspension assembly. In such applications, the modular front drivetrain advantageously enables the entire drivetrain and suspension assembly to be quickly and easily replaced in the event of a part failure, unlike in the case of conventional off-road vehicles that may be sidelined during a race due to the failure of an individual part comprising the drivetrain or the suspension. The frontward stays  360  operate to couple the modular front drivetrain to the chassis  116 . Opposite of the frontward stays  360 , the front hoop  352  is joined to opposite ends of a dash bar  364  and hinge pillars  368  comprising the passenger cabin portion  336 . 
     With continuing reference to  FIG. 7 , a front strut crossmember  372  comprises a portion of the front hoop  352  between the driver-side and passenger-side of the front hoop  352 . The front strut crossmember  372  provides a means for coupling front struts  376  to the chassis  328 , as shown in  FIG. 6 . As best shown in  FIG. 8 , front strut braces  380  are disposed between the front strut crossmember  372  and the dash bar  364 . The front strut braces  380  are configured to reinforce the front strut crossmember  372 , such that loading on the front strut crossmember  372  by the front struts  376  and the bulkhead  340  is distributed to the dash bar  364 . As shown in  FIG. 10 , one end of each front strut brace  380  is coupled to a location of a front strut crossmember  372  that is above a top mount  384  of each front strut  376  (see  FIG. 6 ). Further, each front strut brace  380  is coupled to the front strut crossmember  372  near the joining of the forward stays  360  and the front strut crossmember  372 . As such, forces on the front strut crossmember  372  by the front struts  376  and the bulkhead  340 , during operation of the vehicle  300 , are shared by the dash bar  364 . 
     With continuing reference to  FIG. 7 , the floor hoop  388  generally defines a floor of the passenger cabin portion  336 . Longitudinal floor bars  392  and crossmembers  396  coupled with the floor hoop  388  impart structural strength to the passenger cabin portion  336  and facilitate coupling various components to the floor of the passenger cabin portion  336 . At a front-most position of the floor hoop  388  bulkhead mount pillars  400  extend vertically to a bulkhead mount crossmember  404  disposed between the hinge pillars  368 . As best shown in  FIGS. 8-9 , the bulkhead mount pillars  400  and the bulkhead mount crossmember  404  serve to support a rear portion of the bulkhead  340 . Further, a brace  408  extends from a midpoint of the bulkhead mount crossmember  404  to the dash bar  364 . As such, loading on the bulkhead mount crossmember  404 , during operation of the vehicle  300 , is distributed throughout the chassis  116 . 
       FIG. 11  illustrates a perspective view of an exemplary embodiment of a front structural bulkhead  340  that may be incorporated into an off-road vehicle  300  in accordance with the present disclosure. The front structural bulkhead  340  includes a modular chassis  412  that may support any one or more of a transaxle, a front differential, a steering gear  416 , a braking system, and the like, that are operably coupled with the front wheels  324  by way of the front suspension system  328 , as shown in  FIGS. 5-6 . Further, the modular chassis  412  provides mounting points for the front suspension  328 , in lieu of conventional mounting points that comprise portions of the chassis  116  of the vehicle  300 . In particular, the modular chassis  412  includes lower mounting points  420  for coupling with lower control arms  424  (see  FIG. 12 ) comprising the front suspension  328 . Further, the modular chassis  412  includes upper mounting points  428  for coupling with upper control arms  432  comprising the front suspension  328 . It is to be understood, therefore, that the front structural bulkhead  340  comprises a single drivetrain/suspension assembly that may be installed onto and removed from the vehicle  300 , unlike a conventional drivetrain and suspension that comprise multiple components that must be individually assembled onto the chassis  116  of the vehicle  300 . Further, the front structural bulkhead  340  integrates the transaxle, the front differential, the steering gear  416 , and the front suspension system into the chassis  116 . 
     It is contemplated that the modular chassis  412  may include a braking system configured to enable a practitioner to slow the rotation rate of the front wheel  324  during operation of the vehicle  300 . For example, in some embodiments, brake calipers may be fastened onto the modular chassis  412  such that brake discs coupled to drive axles of the vehicle  300  pass within the brake caliper. Thus, when the practitioner depresses a brake pedal of the vehicle  300  the brake calipers apply pressure to the brake discs, slowing the rotation rate of the front wheels  324 . The brake calipers may be cable operated or may be operated by way hydraulic lines. Although not shown herein, the brake discs may be coupled with a hub comprising the front differential. In some embodiments, however, the brake discs may be coupled with constant velocity joints that are coupled with the hub of the front differential. It is contemplated that the brake calipers and the brake discs may be incorporated into the front structural bulkhead  340  in a wide variety of configurations, without limitation, and without deviating beyond the scope of the present disclosure. 
     As disclosed hereinabove, the front structural bulkhead  340  also supports the steering gear  416  and steering rods  436  (see  FIG. 12 ), such that turning the steering gear  416 , by way of a steering wheel of the vehicle  300 , causes the front wheels  324  to articulate horizontally with respect to the front structural bulkhead  340 . Further, the upper and lower mounting points  428 ,  420  comprising the modular chassis  412  are configured to allow the front wheels  324  to move vertically from a low position (e.g., due to “maximal bounce”) to a high position (e.g., due to “maximal bump”). As such, the front structural bulkhead  340  is not limited to the specific configuration shown in  FIG. 11 , but rather the configuration of the front structural bulkhead  340  may be varied in accordance with the configuration of each of the components comprising the front suspension system  328 , without limitation. 
     Moreover, the front structural bulkhead  340  generally may be varied in accordance with the specific type of vehicle  300  into which the front structural bulkhead  340  is to be implemented. It is contemplated that the front structural bulkhead  340  may be implemented in any of various off-road vehicles  300 , such as, by way of non-limiting example, Utility Task Vehicles (UTVs), Recreational Off-Highway Vehicles (ROVs), or Multipurpose Off-Highway Utility Vehicles (MOHUVs), without limitation. As such, the front structural bulkhead  340  is particularly well-suited for off-road racing applications, such as desert racing, short course racing, hill climbing, rallying, and the like. 
       FIG. 12  illustrates a close-up view of an exemplary embodiment of the front structural bulkhead  340  incorporated into the off-road vehicle  300 , according to the present disclosure. As shown in  FIG. 12 , an upper control arm (UCA)  432  and a lower control arm (LCA)  424  comprising the front suspension system  328  couple the front wheels  324  (see  FIGS. 5-6 ) with the front structural bulkhead  340 . The UCA  432  comprises two inboard UCA joints  440  that couple the UCA  432  to upper mounting points  428  of the front structural bulkhead  340  and an outboard UCA joint (not shown) that couples the UCA  432  to a spindle assembly  444  (see  FIGS. 5-6 ). The LCA  424  includes two inboard LCA joints  448  that couple the LCA  424  to the front structural bulkhead  340  and an outboard LCA joint (not shown) that couples the LCA  424  to the spindle assembly  444 . 
     As will be recognized, the UCA and LCA  432 ,  424  generally are of a double wishbone variety of suspension that facilitates vertical motion of the front wheels  324  during travel over terrain, as well as facilitating horizontal turning of the front wheels  324  during steering of the vehicle  300  by way of the steering gear  416  (see  FIG. 11 ). The UCA and LCA  432 ,  424  further facilitate controlling various parameters affecting the orientation of the front wheels  324  with respect to the off-road vehicle  300 , such as, by way of non-limiting example, camber angle, caster angle, toe pattern, roll center height, scrub radius, and scrub. Further, a steering rod  452  coupling each front wheel  324  (see  FIGS. 5-6 ) with the steering gear  416  mounted on the front structural bulkhead  340  allows for vertical movement and horizontal turning of the front wheels  324  during operation of the vehicle  300 . 
     In addition to the off-road applications discussed above, it is contemplated that, in some embodiments, the front structural bulkhead  340  may be incorporated into racing vehicles that are not necessarily intended for off-road racing. For example, the front structural bulkhead  340  may be incorporated into racing vehicles that may be used for any of formula racing, sports car racing, stock car racing, drag racing, touring car racing, production car racing, as well as amateur open-wheel racing applications, such as karting, and the like, without limitation. 
     While the modular front drivetrain and methods have been described in terms of particular variations and illustrative figures, those of ordinary skill in the art will recognize that the modular front drivetrain is not limited to the variations or figures described. In addition, where methods and steps described above indicate certain events occurring in certain order, those of ordinary skill in the art will recognize that the ordering of certain steps may be modified and that such modifications are in accordance with the variations of the modular front drivetrain. Additionally, certain of the steps may be performed concurrently in a parallel process, when possible, as well as performed sequentially as described above. To the extent there are variations of the modular front drivetrain, which are within the spirit of the disclosure or equivalent to the modular front drivetrain found in the claims, it is the intent that this patent will cover those variations as well. Therefore, the present disclosure is to be understood as not limited by the specific embodiments described herein, but only by scope of the appended claims.