WO2018161117A1

WO2018161117A1 - Modification of a two-wheel drive vehicle for improved ground clearance and/or traction

Info

Publication number: WO2018161117A1
Application number: PCT/AU2018/050205
Authority: WO
Inventors: Phillip James Hargreaves; Stephen Richard William Hargreaves; Isaac John Rattey; Jason Allen Sladden; Brandon James Hargreaves-Wall
Original assignee: Bus IP Holdings Pty Ltd
Priority date: 2017-03-10
Filing date: 2018-03-06
Publication date: 2018-09-13
Also published as: AU2018231941A1; AU2018231941B2

Abstract

A conversion system for modifying a two-wheel drive vehicle, the vehicle having at least two spaced apart rear wheels driven by a rear axle assembly coupled to a transmission output of the vehicle and two front wheels, each front wheel supported by a steerable independent suspension assembly, said front wheels not being coupled to the transmission output of the vehicle, the system comprising: a front axle assembly comprising spaced apart stub axle assemblies for supporting each of the front wheels of the vehicle wherein each stub axle assembly is adapted to be coupled to the steerable independent suspension assembly for supporting a corresponding front wheel of the vehicle; a front differential assembly to be coupled to the spaced apart stub axle assemblies adapted for driving said front wheels; and a sub-frame for attachment to a chassis of the vehicle for mounting and supporting the independent suspension assembly and the front axle assembly.

Description

MODIFICATION OF A TWO-WHEEL DRIVE VEHICLE FOR IMPROVED GROUND

CLEARANCE AND/OR TRACTION

TECHNICAL FIELD

[001 ] The present invention relates to the modification of a two-wheel drive vehicle by increasing the ground clearance of the vehicle and/or improving traction of the vehicle by conversion of the vehicle to a four wheel drive vehicle. The invention is particularly but not exclusively directed to vehicles such as buses and trucks.

BACKGROUND

[002] Any references to methods, apparatus or documents of the prior art are not to be taken as constituting any evidence or admission that they formed, or form part of the common general knowledge.

[003] Two-wheel drive automotive vehicles, particularly vehicles such as buses, vans and trucks are being used increasingly in areas where proper sealed roads are not available. For negotiating such areas, it is desirable to have improved ground clearance and four-wheel drive (4WD) or All Wheel Drive (AWD) capability. 4WD or AWD with improved ground clearance are ideally suited for traveling off road over rough undulating surfaces that offer reduced traction when compared with sealed roads.

[004] Modification of vehicles such as vans, buses and trucks from Two Wheel Drive (2WD) for improving the ground clearance and conversion of the 2WD vehicles to 4WD is known in the art. Generally, conversion of a 2WD vehicle to a 4WD vehicle requires substantial effort and reconfiguration, of the vehicle engineering. For example, a conventional 4WD bus or van converted from a rear- wheel drive vehicle, requires a replacement front axle assembly, for driving the front wheels. The replacement front axle assembly in the prior art typically includes a differential that is coupled with a transfer case assembly which is provided for simultaneously distributing power from the engine to the front wheels and the rear wheels. 4WD conversion kits and methods that are presently known in the art utilize a "live axle" design for carrying out such a 4WD conversion. The use of a "live axle" design in the prior art involves a solid front beam design for driving the front wheels of the converted vehicle. The beam-type axle is the oldest and simplest of sprung axle arrangements known in the automotive industry. However, the use of a live axle beam arrangement has several disadvantages. First, the vertical motion of the wheel unfortunately tilts the axle-beam and transmits some of the bump or rebound movement from one end of the axle-beam to the other. This deflection can cause an oscillating tilting motion of the axle-beam, known as axle 'tramp', which is felt as a tremor of vibration on the steering wheel. Further, the use of the live axle beam design results in the steering geometry not being accurately controlled. By way of example, the change in camber angle that occurs when one wheel strikes a bump can also be significant. Generally, the ride and handling of a converted 4WD vehicle fitted with a front a beam type front axle is significantly compromised.

[005] Whilst, a conventional beam axle design provides strength, rigidity, accurate steering and tire-wear control such an arrangement translates a singular tire input (bump) to the other side wheel, thereby affecting steering performance parameters to the vehicle.

[006] It has also been found that converted 4WD vehicles which utilize a "live axle beam" design do not allow any adjustment in camber, caster and wheel alignment. The "live beam" configuration of the front axle in such converted 4WD vehicles is also susceptible to damage leading to misalignment due to undesirable variation in the suspension alignment geometry. The "live beam" design is also usually heavy which invariably increases the "unsprung" weight of the vehicle. As a result, ride quality and comfort is significantly compromised.

[007] In view of the above, there is a need for providing an improved 4WD conversion kit or system which addresses some of the shortcomings of the currently known kits.

SUMMARY OF THE INVENTION

[008] In one aspect, the invention provides a conversion system for modifying a two- wheel drive vehicle, the vehicle having at least two spaced apart rear wheels driven by a rear axle assembly coupled to a transmission output of the vehicle and two front wheels, each front wheel supported by a steerable independent suspension assembly, said front wheels not being coupled to the transmission output of the vehicle, the system comprising: a front axle assembly comprising spaced apart stub axle assemblies for supporting each of the front wheels of the vehicle wherein each stub axle assembly is adapted to be coupled to the steerable independent suspension assembly for supporting a corresponding front wheel of the vehicle;

a front differential assembly to be coupled to the spaced apart stub axle assemblies adapted for driving said front wheels; and

a sub-frame for attachment to a chassis of the vehicle for mounting and supporting the independent suspension assembly and the front axle assembly.

[009] In an embodiment, the system further comprises: a transfer case assembly coupled to the front axle assembly and the rear axle assembly for simultaneously transferring torque from the transmission output to the front and rear wheels respectively.

[010] In an embodiment, the front differential assembly comprises a front differential housed in a differential housing for driving the front wheels, the housing being mounted relative to the sub-frame.

[01 1 ] In an embodiment, the differential housing is integrally formed with the sub-frame whereby the differential housing comprises one or more mounting attachments for mounting the housing to the chassis of the vehicle. The sub-frame also comprises one or more upwardly extending mounting attachments for mounting said sub-frame to the chassis of the vehicle.

[012] Preferably, the sub-frame comprises a transversely extending connecting member for inter-connecting the sub-frame with the differential housing.

[013] In an embodiment, the front differential is connected to one of a propeller shaft, the opposite end of which is interconnected to a front driveshaft assembly coupled with the transfer case assembly.

[014] In an embodiment, each of the steerable independent suspension assembly comprises a pair of upper arms, each upper arm having a first end and a second end, wherein a first end of the upper arm is adapted to be coupled to an upper portion of the stub assembly and wherein the second end of the upper arm is pivotally mounted with respect to the chassis. [015] In an embodiment, the steerable independent suspension assembly further comprises a pair of lower arms, each lower arm having a first end and a second end, wherein the system further comprises a mounting arrangement such that a lower portion of the mounting arrangement is coupled to the first end of each lower arm and the sub- frame is adapted to be coupled to the second end of the lower arm.

[016] In an embodiment, the sub-frame comprises a first rear frame member having two opposed ends, each opposed end of the end being adapted for being coupled to the second end of a respective lower arm of one of said pair of lower arms. The sub-frame may also comprises a forwardly positioned frame member having opposed ends, each opposed end of the forwardly positioned frame being adapted to be coupled to the second end of a respective lower arm of the other of said lower arms. Preferably, the forwardly positioned member is integrally formed with differential housing.

[017] In an embodiment, each of the steerable independent suspension assembly comprises a shock absorbing member with an upper end of the shock absorbing member being mounted to the chassis or vehicle frame and wherein a lower end of the shock absorbing member is adapted to be mounted to an upper portion of the mounting arrangement to maintain the travel length of the shock absorbing member after the conversion.

[018] In an embodiment, the stub axle assembly comprises a downwardly dependent attachment arm, wherein an upper end of the attachment arm is pivotally fastened to the first end of the upper arm and wherein a lower end of the attachment arm supports a stub axle having an outwardly extending spindle having a longitudinal axis that defines a wheel axis of rotation for each respective front wheel. Preferably, the system further comprises a movable joint attachment for attaching the upper portion of the attachment arm to the upper control arm.

[019] In an embodiment, each of the stub axle assembly comprises a steering knuckle for pivotally linking the stub axel assembly to a tie rod arm of a steering arrangement of the vehicle. [020] In an embodiment, the system further comprises an outer drive axle for driving each front wheel coupled to a corresponding stub axle, wherein a flanged end of the outer drive axle is coupled a hub assembly mounted to the corresponding stub axle and wherein a splined end of the outer drive axle is coupled to an outer constant velocity joint.

[021 ] In an embodiment, the system further comprises a differential axle coupled to inner constant velocity joints for transferring drive from the front differential to the front wheels.

[022] In an embodiment, the inner constant velocity joint and the outer constant velocity joint are coupled to each other by a constant velocity driveshaft.

[023] In an embodiment, the system further comprises a guard assembly for mounting the transfer case assembly relative to the sub-frame.

[024] In an embodiment, the guard assembly comprises:

a mounting bracket adapted for being fastened to a housing of the transfer case assembly; and

a guarding member for protecting the transfer case assembly from being impacted during use.

[025] In another aspect, the invention provides a kit of parts which can be installed to modify a two-wheel drive vehicle, said two wheel drive vehicle having at least two rear wheels coupled to a transmission output of the vehicle and two front wheels, each front wheel supported by a steerable independent suspension assembly, the kit comprising: a front axle assembly comprising spaced apart stub axle assemblies for supporting each of the front wheels of the vehicle wherein each stub axle assembly is adapted to be coupled to the steerable independent suspension assembly for supporting a corresponding front wheel of the vehicle;

a front differential assembly adapted to be coupled to the spaced apart stub axle assemblies adapted for driving said front wheels; and

a sub-frame for attachment to a chassis of the vehicle for mounting and supporting the independent suspension assembly and the front axle assembly. [026] In an embodiment, the kit further comprises: a transfer case assembly coupled to the front axle assembly and the rear axle assembly for simultaneously transferring torque from the transmission output to the front and rear wheels respectively.

[027] In another aspect, the invention provides a method of modifying a two-wheel drive vehicle having at least two rear wheels coupled to a transmission output of the vehicle and two front wheels, each front wheel supported by a steerable independent suspension assembly, the method comprising:

uncoupling each stub axle from the independent suspension assembly;

positioning a front axle assembly comprising respective replacement stub axle assemblies for supporting front wheels of the vehicle ;

coupling the independent suspension assembly with the front axle assembly including the replacement stub axle assemblies for supporting a corresponding front wheel; and

mounting and supporting the independent suspension assembly and the front differential assembly on a sub-frame.

[028] In an embodiment, the method further comprises the steps of:

arranging a front differential assembly relative to the front axle assembly to couple said front differential assembly with the replacement stub axle assemblies for driving said front wheels; and

coupling a transfer case assembly to the front axle assembly and a rear axle assembly of the vehicle for simultaneously transferring torque from the transmission output to the front and rear wheels respectively.

BRIEF DESCRIPTION OF THE DRAWINGS

[029] Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The Detailed Description will make reference to a number of drawings as follows: [030] Figure 1 is a perspective view of an installed conversion kit/system 100 for converting a two-wheel drive vehicle to a four-wheel drive vehicle in accordance with an embodiment of the present invention.

[031 ] Figure 2 is a side view of the conversion system 100.

[032] Figure 3 is an in-use enlarged view of the front axle assembly 140.

[033] Figure 4 is a frontal view of the front axle assembly 140.

[034] Figure 5 is a rear perspective view of the front axle assembly 140. Figure 5A is an enlarged view of the mounting bracket 167.

[035] Figures 5B provides a rear view of the sub-frame 300 formed integrally with the differential housing 142.

[036] Figure 5C provides a top perspective view of the sub-frame 300 formed integrally with the differential housing 142.

[037] Figure 6 is an in-use perspective view of the independent suspension assembly 160 from the two wheel drive vehicle which has been coupled with the stub axle assembly 150 of the conversion system/kit 100.

[038] Figure 7 is an in-use frontal perspective view of the independent suspension assembly 160 from the two wheel drive vehicle which has been coupled with the stub axle assembly 150 of the conversion system/kit 100. Inset shows an enlarged view of ball mount joint 165.

[039] Figure 8 is an in-use top perspective view of the transfer case assembly 130.

[040] Figure 9 is an in-use frontal perspective view of the transfer case assembly 130.

[041 ] Figure 10 is a partial top view of the conversion system/kit 100 illustrating the rear axle assembly 120 coupled with the transfer case assembly 130. [042] Figure 1 1 and 12 illustrate various in-use views of a guard assembly 290 for mounting and guarding the transfer case assembly 130.

[043] Figure 13 is an isolated perspective view of the stub axle assembly 150.

[044] Figures 14 and 15 are in-use perspective views of the stub axle assembly 150.

[045] Figure 16 is a perspective view of an outer drive axle 210.

[046] Figure 17 is a perspective view of a differential drive axle (driver's side) 240.

[047] Figure 18 is a perspective view of a differential drive axle (passenger's side) 260.

[048] Figure 19 is a perspective view of an input drive shaft 132 for transferring drive (or power) from the transmission output to the transfer case assembly 130.

[049] Figure 20 is a perspective view of a constant velocity driveshaft 280.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[050] Referring to Figures 1 to 12, there are shown details of a conversion system/kit 100 that is shown in an installed configuration. The conversion system/kit 100 comprising various parts which can be installed to convert a 2WD vehicle to a 4WD or an AWD vehicle.

[051 ] The kit 100 illustrated herein is specifically well suited for the Toyota Coaster bus/van chassis 1 10. It is to be noted that chassis frame 1 10 has been illustrated without the bus/van body being shown for ease of illustration and understanding. However, the presently described embodiments are not limited to use with the chassis frame 1 10 having a specified shape (as shown) and encompass use of the chassis frame 1 10 with a vehicle body of any size or shape adapted to be mounted onto the chassis frame 1 10. The scope of the kit 100 illustrated herein is in no way limited to a specific model of a vehicle and other embodiments may be configured for use with vehicles of other make or model without departing from the scope of the invention. [052] The conversion system/kit 100 is particularly suited for modifying a two-wheel drive vehicle having at least two spaced apart rear wheels driven by a rear axle assembly coupled to a transmission output of the vehicle and two front wheels. The conversion system/kit 100 is specifically useful for rear wheel driven heavy vehicles such as buses or trucks in which the front wheels are not coupled to the transmission output and are supported steerable independent suspension assembly for each front wheel.

[053] During installation of the kit 100, the rear axle assembly 120 includes an integral differential housing 122 and an integral rear differential within the rear differential housing 122, as supplied in the original 2WD vehicle. The leaf spring suspension system 128 as originally provided in the original 2WD vehicle is utilized during the 4WD conversion. Specifically, the relative orientation of the leaf spring suspension 128 and the rear axle assembly 120 is altered by shifting the rear axle assembly 120 below the leaf spring suspension system 128. During the conversion process, a leaf spring suspension system 128 (as originally provided in the vehicle pre-conversion) is uncoupled from the chassis of the supplied vehicle and positioned in a spaced arrangement above the rear axle assembly 120 (in an underslung configuration) by positioning saddle members (provided with the kit 100) in between the rear differential housing 122 and the leaf spring suspension 128. The placement of the saddle members in the converted vehicles assists in providing an overall increase in the ground clearance of the bus/van body mounted upon the chassis frame 1 10. The saddle also allows for the correct pinion angle on the rear axle 120 and provide a new mounting location for the leaf spring suspension 128.

[054] The kit 100 also comprises a transfer case assembly 130 that is provided for simultaneously transferring torque from the transmission output shaft of the vehicle to the front and rear wheels of the vehicle. The transfer case assembly 130 comprises an input shaft 132 (shown clearly in Figure 25) which transfers torque from the transmission output shaft of the vehicle to an input of the transfer case assembly 130. The spline of the input shaft 132 comprises a male end 132A portion which is configured to be coupled to a corresponding female spline provided in the transfer case assembly 130. The flanged portion 132B of the input shaft 132 (shown in Figure 25) is adapted to be coupled with the transmission output (via a driveshaft). The shoulder and groove in the input shaft 132 have been designed to allow the use of a double row ball bearing for support and a circlip for securing of the shaft 132 & bearing. [055] The transfer case assembly 130 is coupled with the rear driveshaft assembly 133 and the front driveshaft assembly 134 (shown in Figure 10) for simultaneously transferring torque to the rear axle 120 and a front axle 140 respectively. Such an arrangement of the transfer case 130 results in providing All Wheel Drive (AWD) capability to the converted vehicle. As a result, all four wheels of the converted vehicle are driven at all times by the transmission output of the vehicle. In the preferred embodiment, a commercially available transfer case, namely a Toyota Landcruiser 200 series transfer case assembly is utilized for the kit 100. However, any other transfer case may also be used without departing from the scope of the invention.

[056] It would be understood that the transfer case assembly 130 can be equipped with a gear reduction and a synchronized range shift mechanism to permit "on-the-move" shifting between high-range and low-range drive modes. The synchronized range shift mechanism may also permit the vehicle operator to shift the transfer case between high- range and low-range drive modes without stopping the vehicle.

[057] During installation, a guard assembly 290 (best shown in Figures 10 to 12) may also be used for protecting the transfer case assembly 130 from being impacted during use. The guard assembly 290 comprises a mounting bracket 294 adapted for being fastened to a housing of the transfer case assembly 130 and a guarding member 292 for protecting the transfer case assembly 130 from being impacted during use.

[058] The kit 100 also comprises a replacement front wheel axle 140 as shown most clearly in Figures 1 to 5. A pair of front wheels are connected at opposite ends of the front axle assembly 140. The front axle assembly comprises a front differential (not shown) that is housed within the front differential housing 142. The front differential is coupled to one end of a front propeller shaft 146, the opposite end of which is interconnected to the front driveshaft assembly 134 working in conjunction with the transfer case assembly 130. During use, the transfer case 130 transfers torque to the front driveshaft assembly 134 (which is inter-connected to the propeller shaft 146). The front differential 144 distributes rotational torque to the front wheels supported by the front axle 140. In the preferred embodiment, a series of constant velocity (CV) joints are coupled with the front differential 144 for powering the front wheels of the vehicle. A detailed description of the CV joints has been provided in the foregoing sections. [059] The front axle assembly 140 also comprises respective stub axle assemblies 150 which are mounted at either end of the front axle assembly 140. The purpose of the stub axle assembly 150 is to allow for mounting of the wheel, the wheel hub assembly 190, brake rotors and associated components whilst accommodating for the independent front suspension assembly 160 from the two wheel drive vehicle. It is important to appreciate that one of the key advantages afforded by the present invention is the ability of the conversion system/kit 100 to be retrofitted into an existing chassis 1 10 of the vehicle and utilise the vehicle's existing independent suspension assembly 160 supporting each front wheel. Unlike currently known conversion systems which utilise a beam type axle with leaf spring suspension, the presently described conversion system/kit 100 retains the vehicle's OEM (original equipment manufacturer) independent suspension parts whilst also allowing conversion of the two wheel drive vehicle into a four wheel drive vehicle. Such a conversion system/kit provides significantly improved steering handling and shock absorbing capacity for the converted vehicle when compared with currently known conversion systems. The conversion system/kit 100 also allows factory warranty of the chassis and shock absorbing system to be retained by maximising the use of the vehicle's OEM parts.

[060] Referring to Figures 6, 7 and 13 to 15, detailed views of the stub axle assembly 150 are illustrated. The stub axle assembly 150 includes a downwardly dependent attachment arm 152 that is connected with the stub axle 154. The attachment arm 152 may be formed integrally with the stub axle in some embodiments. An upper portion of the attachment arm 152 allows the stub axle 154 to be attached to the independent front suspension assembly 160 by a mounting arrangement 165 (that has been described in further detail). A steering knuckle 157 is also provided for pivotally linking the stub axel assembly 150 to a tie rod arm of a steering arrangement of the vehicle (not shown).

[061 ] The independent front suspension assembly 160 is coupled to the stub axle assemblies 150 provided at either end of the front axle assembly 140. The stub axle assembly 150 engages the independent suspension assembly 160 through the upper 'A' shaped upper control arms 162 and lower control arms 164. Each upper arm 162 comprises a first end and a second end, wherein a first end of the upper arm is adapted to be coupled to an upper portion of the attachment arm 152 of the stub assembly 150and wherein the second end of each upper control arm 162 is pivotally mounted with respect to the chassis 1 10. A lower portion 1 54 of the stub axle assembly forms the stub axle and includes an outwardly extending spindle 156 having a longitudinal axis that defines a wheel axis of rotation for each respective front wheel.

[062] Each lower arm 164 also comprises a first end and a second end. A mounting arrangement in the form of a mounting bracket 167 is provided. A lower portion of the mounting bracket 167 is coupled to the first end of each lower control arm 164. The second end of the lower control arm 164 is coupled to a sub-frame 300 as shown in Figures 5 and 6. The sub-frame 300 provides rigid and adjustable mounting of the replacement front differential housing 142 and the lower control arms 164. During installation, the original suspension mounts may be used in conjunction with control arm bushes as originally provided to keep the sub-frame assembly 300 frame isolated from the chassis frame 1 10 by using bushes.

[063] Referring to Figures 4, 5 and 5A, a resilient shock absorber and/or strut member 169 from the independent suspension assembly 160 of the original two wheel drive vehicle (pre-conversion) is mounted between the lower control arm 164 and the chassis frame 1 10 by a strut mounting arrangement 168 provided on an upper portion of the mounting bracket 167. A bump stopping arrangement is also located adjacent the mounting arrangement. A lower portion of the mounting bracket 167 is coupled with the lower control arms 164 and the sub-frame 300. Advantageously, the mounting bracket 167 is configured to maintain the travel length of the shock absorbing member 169.

[064] The kit 100 also includes a ball joint attachment 165 (shown clearly in Figures 6 and 7) provided for connecting the attachment arm 152 of the stub axle assembly 150 with the upper control arms 162. The ball joint attachment 165 allows slight relative movement between the upper control arms 162 and the stub axle assembly 150. The ball joint attachment 165 also allows the independent suspension assembly 160 and the CV joint assembly to be accommodated in the vicinity of the front wheel axle 140.

[065] Referring to Figures 5B and 5C isolated views of the front differential assembly 140 and the sub-frame 300 are illustrated. The front differential housing 142 is integrally formed with the sub-frame 300 to allow the kit/system 100 to be easily integrated with the existing independent suspension assembly 160 of the vehicle. The sub-frame 300 comprises a rear frame member 305 extending between two opposed ends 322 and a forwardly positioned member 307 extending between two opposed ends 324. The rear and forward members 305 and 307 are inter-connected by a transversely arranged member 330. As is evident from the Figures 5B and %c, the differential housing 142 is formed integrally with the forwardly positioned frame member 307. Mounting attachments 345 on the forwardly extending frame member 307 allow the differential housing to be easily mounted onto the chassis of the vehicle during installation of the kit/system 100. Upwardly extending mounting attachments 310 are also provided on the rear frame member 305. The opposed ends 322 and 324 of each of the front and rear frame members 305 and 307 are adapted to be coupled to the lower control arms of the existing independent suspension assembly 160 of the vehicle. Therefore, the configuration of the sub-frame in combination with the front differential assembly 100 is very important for allowing the kit/system 100 to utilise the existing independent suspension assembly 160 of the vehicle.

[066] The provision of a replacement frontal axle assembly 140 in the aforementioned configuration in combination with the independent suspension assembly 160 provides a significant improvement over the prior art by way of providing much improved handling characteristics for the converted 4WD or AWD vehicle. The converted 4WD or AWD vehicle also provides a significantly improved and comfortable ride when compared with vehicles that had been converted using previously available kits and methods. Another significant advantage of the improved kit 100 is that the original suspension assembly of the original 2WD vehicle (pre-conversion) no longer needs to be disposed. Instead, the improved kit 100 utilizes various parts of the original suspension assembly thereby improving utilization of the original parts of the 2WD vehicle whilst providing improved 4WD or AWD capability once the conversion has been completed. The kit 100 has been designed for maximum serviceability through improving and maximizing the use of genuine parts from the original 2WD vehicle. Another significant advantage of the kit 100 in accordance with an embodiment is that by maximizing the use of genuine vehicle components (as originally provided in the initial 2WD vehicle), the converted 4WD or AWD vehicle can be serviced relatively easily at the authorized service centers of the vehicle manufacturer.

[067] The kit 100 also comprises an outer drive axle 210 (shown in Figure 16) for driving the front wheel through the stub axle 154. A flanged end 212 of the outer axle 210 is designed to mount to the hub assembly 190 mounted on the front of the stub axle 154. A splined end 214 of the outer drive axle 210 coupled with an outer constant velocity joint 230 (shown in Figures 4 and 5A). The splined end 214 couples with a female coupling to transfer drive from the outer constant velocity joint 230. The female coupling joint may be supported by a bearing and secured by circlips to ensure no axial or radial movement occurs.

[068] The kit 100 also comprises a first differential axle 240 (driver's side-Figure 17) and a second differential axle 260 (passenger's side-Figure 18) which are coupled with the front differential (housed in the front differential housing 142) to respective inner constant velocity joints 250. The first differential axle 240 has been designed with a flanged end to be secured to the inner constant velocity joint 250 with 6 bolts. The first differential axle 240 and the second differential axles 260 are designed with the appropriate length to allow for the inner constant velocity joint 250 to have appropriate clearance relative to the chassis 1 10 and any other components such as the mounting bracket 167. The flanged end of each of the differential axles 240 and 260 also allows for a grease retaining cap to be positioned on the constant velocity joint. It is important to note that in the preferred embodiment, the length of the first differential axle 240 is not the same as the second differential axle 260.

[069] The outer CV joint 230 and the inner CV joint 250 are coupled by a CV driveshaft 280 (shown in Figure 20) that connects the CV joints. The positioning of the spline and the grooves provided in the CV drive shaft 280 allows the shaft 280 to be secured to the outer CV joint 230 and the inner CV joint 250. An extended spline portion along the inner end of the drive shaft allows for changes in length between the CV joints 230 and 250 during installation. Raised shoulder sections in the CV driveshaft are provided to ensure that the CV boots have a location to be securely clamped the driveshaft 280.

[070] In another embodiment, the kit 100 may also be modified to be used as a lifting kit 100' (not shown in the drawings) for increasing the ground clearance of a two-wheel drive vehicle such as a bus or a van without necessarily providing torque to the front wheels of the vehicle. Like reference numerals denote like features that have been previously described in the earlier sections. Specifically, a modified front axle assembly 140' with respective stub axle assemblies 150 may be used for supporting the front wheels of the vehicle without necessarily installing a front differential (unlike the previously described embodiment). An independent suspension assembly 160 may also be coupled to the respective stub axle assemblies 150 for supporting a corresponding front wheel of the vehicle during a routine installation. The sub-frame 300 may also be used for supporting the lower control arms 164 of the independent suspension assembly 160. Unlike the previously described embodiment (which relates to a 4WD or an AWD conversion system), the transfer case assembly 130 does not need to be installed for undertaking the installation of the lift kit 100'. In further improvements, users of the lift kit 100' may upgrade their lifted vehicles further by installing the transfer case assembly 130 and the front differential 144 with the associated front and rear drive shaft assemblies to simultaneously provide torque to the front and rear wheels of the vehicle.

[071 ] In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. The term "comprises" and its variations, such as "comprising" and "comprised of" is used throughout in an inclusive sense and not to the exclusion of any additional features.

[072] It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect.

[073] The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted by those skilled in the art.

[074] Throughout the specification and claims (if present), unless the context requires otherwise, the term "substantially" or "about" will be understood to not be limited to the value for the range qualified by the terms.

[075] Any embodiment of the invention is meant to be illustrative only and is not meant to be limiting to the invention. Therefore, it should be appreciated that various other changes and modifications can be made to any embodiment described without departing from the spirit and scope of the invention.

Claims

The claims defining the invention are as follows:

1 . A conversion system for modifying a two-wheel drive vehicle, the vehicle having at least two spaced apart rear wheels driven by a rear axle assembly coupled to a transmission output of the vehicle and two front wheels, each front wheel supported by a steerable independent suspension assembly, said front wheels not being coupled to the transmission output of the vehicle, the system comprising:

a front axle assembly comprising spaced apart stub axle assemblies for supporting each of the front wheels of the vehicle wherein each stub axle assembly is adapted to be coupled to the steerable independent suspension assembly for supporting a corresponding front wheel of the vehicle;

2. A system in accordance with claim 1 further comprising: a transfer case assembly coupled to the front axle assembly and the rear axle assembly for simultaneously transferring torque from the transmission output to the front and rear wheels respectively.

3. A system in accordance with claim 2 wherein the front differential assembly comprises a front differential housed in a differential housing for driving the front wheels, the housing being mounted relative to the sub-frame.

4. A system in accordance with any one of claim 2 or 3 wherein the front differential is connected to one of a propeller shaft, the opposite end of which is interconnected to a front driveshaft assembly coupled with the transfer case assembly.

5. A system in accordance with any one of the preceding claims wherein each of the steerable independent suspension assembly comprises a pair of upper arms, each upper arm having a first end and a second end, wherein a first end of the upper arm is adapted to be coupled to an upper portion of the stub assembly and wherein the second end of the upper arm is pivotally mounted with respect to the chassis.

6. A system in accordance with claim 5 wherein the steerable independent suspension assembly further comprises a pair of lower arms, each lower arm having a first end and a second end, wherein the system further comprises a mounting arrangement such that a lower portion of the mounting arrangement is coupled to the first end of each lower arm and the sub-frame is adapted to be coupled to the second end of the lower arm.

7. A system in accordance with claim 6 wherein each of the steerable independent suspension assembly comprises a shock absorbing member with an upper end of the shock absorbing member being mounted to the chassis or vehicle frame and wherein a lower end of the shock absorbing member is adapted to be mounted to an upper portion of the mounting arrangement to maintain the travel length of the shock absorbing member after the conversion.

8. A system in accordance with claim 5 wherein the stub axle assembly comprises a downwardly dependent attachment arm, wherein an upper end of the attachment arm is pivotally fastened to the first end of the upper arm and wherein a lower end of the attachment arm supports a stub axle having an outwardly extending spindle having a longitudinal axis that defines a wheel axis of rotation for each respective front wheel.

9. A system in accordance with claim 8 further comprising a movable joint attachment for attaching the upper portion of the attachment arm to the upper control arm.

10. A system in accordance with any one of claims 5 to 9 wherein each of the stub axle assembly comprises a steering knuckle for pivotally linking the stub axel assembly to a tie rod arm of a steering arrangement of the vehicle.

1 1 . A system in accordance with any one of the preceding claims further comprising an outer drive axle for driving each front wheel coupled to a corresponding stub axle, wherein a flanged end of the outer drive axle is coupled a hub assembly mounted to the corresponding stub axle and wherein a splined end of the outer drive axle is coupled to an outer constant velocity joint.

12. A system in accordance with any one of the preceding claims further comprising a differential axle coupled to inner constant velocity joints for transferring drive from the front differential to the front wheels.

13. A system in accordance with claim 1 2 when dependent upon claim 1 1 wherein the inner constant velocity joint and the outer constant velocity joint are coupled to each other by a constant velocity driveshaft.

14. A system in accordance with any one of claim 2 or claims 3 to 13 when dependent upon claim 2 further comprising a guard assembly for mounting the transfer case assembly relative to the sub-frame.

15. A system in accordance with claim 14 wherein the guard assembly comprises:

16. A kit of parts which can be installed to modify a two-wheel drive vehicle, said two wheel drive vehicle having at least two rear wheels coupled to a transmission output of the vehicle and two front wheels, each front wheel supported by a steerable independent suspension assembly, the kit comprising: a front axle assembly comprising spaced apart stub axle assemblies for supporting each of the front wheels of the vehicle wherein each stub axle assembly is adapted to be coupled to the steerable independent suspension assembly for supporting a corresponding front wheel of the vehicle; a front differential assembly adapted to be coupled to the spaced apart stub axle assemblies adapted for driving said front wheels; and a sub-frame for attachment to a chassis of the vehicle for mounting and supporting the independent suspension assembly and the front axle assembly.

17. A kit in accordance with claim 16 further comprising: a transfer case assembly coupled to the front axle assembly and the rear axle assembly for simultaneously transferring torque from the transmission output to the front and rear wheels respectively.

18. A method of modifying a two-wheel drive vehicle having at least two rear wheels coupled to a transmission output of the vehicle and two front wheels, each front wheel supported by a steerable independent suspension assembly, the method comprising:

uncoupling each stub axle from the independent suspension assembly; positioning a front axle assembly comprising respective replacement stub axle assemblies for supporting front wheels of the vehicle ;

19. A method of modifying a two-wheel drive vehicle in accordance with claim 1 8 further comprising the steps of:

20. A conversion kit comprising the conversion system in accordance with any one of claims 1 to 15.