AU2021204802B2

AU2021204802B2 - Method and apparatus for modification of a motor vehicle suspension

Info

Publication number: AU2021204802B2
Application number: AU2021204802A
Authority: AU
Inventors: Jason Mcintosh
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-03-19
Filing date: 2021-07-08
Publication date: 2022-10-06
Anticipated expiration: 2036-03-17
Also published as: AU2021204802A1; AU2020202596A1; AU2018201171A1; AU2020202596B2; NZ718131A; AU2016201726A1

Abstract

A method of modifying a body-on-frame vehicle suspension for replacing an existing suspension device with an alternative suspension device, for example an air bag or coil spring system and for improving stability of the vehicle chassis includes providing a preassembled structure for installation between and in abutment with the chassis rails and removably securing the structure in place with bolts, the structure being adapted for receiving in operative mounting configuration the alternative suspension device. The structure may be in the form of a frame having formations for accommodating the replacement suspension device and shock absorber components. The frame is adaptable to fit different vehicles and is provided in a do-it-yourself kit.

Description

Method and apparatus for modification of a motor vehicle suspension

Field of invention

[01] This invention relates to a motor vehicle suspension apparatus. The invention relates also to a method and means for replacing a first type of suspension means with a second. The means includes a retrofit kit for a installing a desired replacement suspension system. The invention is suitable for use in relation to a vehicle of the body-on frame type.

Background to the invention

[02] Body-on frame motor vehicles are distinguishable from unibody or monocoque vehicles in that the body (or coach) is mounted on a strong and relatively rigid frame or chassis that carries the powertrain and to which the suspension, wheels and steering are mounted. The body and chassis are separate assemblies. The frame or chassis evolved into what became known as a steel ladder frame or chassis, because of its general resemblance to a ladder. Another form of frame-on body construction is the rolling chassis, comprising the powertrain, suspension, steering column and fuel tank mounted on the chassis frame. To this was added the separate body with its interior fittings. Unibody designs, by contrast, have panels within the body unit supporting the vehicle, typically a passenger car, on its suspension.

[03] Live axle rear suspension systems are usually found on rear and four wheel drive vehicles of body-on-frame construction. These systems consist of leaf or coil springs utilized in conjunction with the live axle, which is the differential axle, wheel bearings, and brakes operating as a unit. The leaf spring suspension is very well suited to load carrying vehicles, but is not suited to passenger cars, because its significant unsprung weight and stiff springs produce a relatively harsher ride.

[04] In vehicles with independent rear suspension, coil springs are advantageously used between the control arm and the vehicle body, and the control arms pivot at one end on a cross-member and are attached at their other end to a spindle. In a non independent rear suspension, coil springs may replace leaf springs, and strut rods and control arms serve to position the rear axle.

[05] It is generally recognized in motoring circles that suspension systems using devices other than leaf springs provide a more comfortable or softer ride than leaf spring suspension. Preferred systems typically employ devices such as coil springs and air bag units. Yet leaf springs are making a comeback, with many vehicles intended for use under hard driving conditions again being fitted with leaf springs. These vehicles typically find use in industrial fleet service.

[06] Vehicle operators wishing to replace leaf springs with alternative devices are able to modify their vehicles by making appropriate adaptations. These require removal of unrequired components and welding in place the necessary attachments for mounting coil springs or air bags (by way of example).

Objects of the invention

[07] It is an object of this invention to address the shortcomings of the prior art and, in doing so, to provide a method and a kit for facilitating the fitting of an alternative suspension device to a vehicle to replace an originally fitted device, for example leaf springs.

[08] A further object of the invention is to provide a structure for fitting to a vehicle to enable the mounting of an alternative suspension device.

[09] The preceding discussion of the background to the invention is intended to facilitate an understanding of the present invention. However, it should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge in Australia or elsewhere as at the priority date of the present application.

[010] Further, and unless the context clearly requires otherwise, throughout the description and the claims, the words 'comprise', 'comprising', and the like are to be construed in an inclusive sense - that is to say, in the sense of "including, but not being limited to" - as opposed to an exclusive or exhaustive sense - that is to say meaning "including this and nothing else".

Summary of invention

[011] According to a first aspect of the invention, there is provided a method of modifying the suspension of a body-on-frame vehicle having left and right chassis rails that extend generally horizontally and in parallel from the front to rear of the vehicle and leaf springs associated with the respective chassis rails, the method comprising steps of:

• Providing a body-on-frame vehicle;

• Removing from the vehicle the leaf springs; • Locating between the chassis rails a pre-assembled structure for accommodating the installation thereon of an alternative suspension device; • Bolting the structure to the rails to be operatively and removably fastened thereto; and • Providing an alternative suspension device and fitting it to the structure in operative, suspension-providing orientation.

[012] In a preferred form of the invention, the step of fitting the structure includes removably securing the structure to the vehicle.

[013] Preferably the structure is removably secured by fastening means, more preferably bolting means.

[014] In a further preferred form of the invention, the step of fitting the structure includes fastening the structure to a chassis rail of the vehicle.

[015] In an embodiment, the method includes suspending the structure from the chassis rail.

[016] In a preferred embodiment, the method includes locating the structure to fit between opposed chassis rails of the vehicle.

[017] In a further form of the invention, the method includes the step of locating the structure to fit between front and rear chassis mountings of the leaf springs being replaced.

[018] Preferably, the structure comprises opposed lip formations that extend below the respective chassis rails.

[019] The method includes preferably urging the structure upward between the chassis rails until the lip formations abut the rails, prevent further relative upward movement. The structure may then be secured to the rails.

[020] The method preferably further includes providing a pair of control arm mounting brackets and extends to securing the brackets in control arm-connecting position on the chassis rail. Preferably, the bracket is located to be displaced from the frame.

[021] In a preferred embodiment, the alternative suspension device comprises a coil spring or a compressible fluid container. Further preferably, the compressible fluid container comprises an air bag.

[022] According to a second aspect of the invention, there is provided a suspension assembly for installation in a body-on-frame motor vehicle having left and right chassis rails, and adapted to be equipped with a first suspension device, the assembly comprising a structure adapted for removable mounting to a chassis rail of the vehicle by fastening means, and locating means for connecting to the structure, in operative orientation at a desired location thereon, a second, alternative suspension device to the first.

[023] The locating means may include engagement means. The engagement means preferably comprises retainer means. The retainer means, in an embodiment, comprises clamping means. The clamping means is preferably adapted for receiving and clamping against the structure a portion of said alternative suspension device.

[024] In a preferred embodiment, the clamping means comprises a retention plate and fastening means for fastening the plate to the structure, while applying clamping force to said portion of the device.

[025] In a preferred form of the invention, the structure comprises a generally rectangular frame. The frame comprises a front element and a rear element having opposed ends to which are connected respective left and right side elements.

[026] In a further preferred form of the invention, the frame is adapted to fit between opposed chassis rails of the vehicle. In a preferred embodiment of the invention, the side elements have laterally extending lip formations for bringing into abutment with an underside portion of the chassis rails.

[027] In another further preferred form of the invention, the structure is adapted for the mounting of an alternative suspension device. To this end the structure is adapted to comprise a mounting plate against which the alternative device is located in operative orientation.

[028] In a still further preferred form of the invention, the mounting plate includes the locating means.

[029] Preferably, the mounting plate extends from the front to the rear elements. Preferably the mounting plate is connected to one of said side elements.

[030] Preferably, the structure comprises paired mounting plates, each being rigidly connected to and extending from front element to rear element. In a preferred embodiment, the mounting plates are respectively connected to the opposing side elements.

[031] In a further preferred form of the invention, the mounting elements are separated from each other by a gap. Preferably, the gap is at least as wide as the wider (if any) of the mounting elements.

[032] In a preferred embodiment, the elements and the mounting plates are connected by welding. Alternatively, the structure may be formed by moulding, or by additive manufacturing, for example a three-dimensional printing technique. In another embodiment, the connections are achieved by fastening means known in the art, for example screw-threaded connectors, rivets and the like.

[033] In a preferred embodiment, the side elements comprise elongate flat plate elements. The elements are manufactured from steel or other suitable alloys known in the motor vehicle component industry. The plate thickness is preferably in the range from 3mm-12mm, more preferably from 5mm-10mm.

[034] Preferably, the frame comprises track guide means extending therefrom. In an embodiment, the track guide means comprises a track bar. In an embodiment, the track guide means is a Panhard rod.

[035] In an alternative form of the invention, the structure further includes mounting brackets for a pair of shock absorbers. Preferably, the shock absorber mounting brackets are located forward of the locating means when the structure is operatively mounted to the vehicle.

[036] Still further, the structure preferably includes a pair of mounting brackets for upper control arms associated with the vehicle suspension. In a preferred embodiment, said upper control arm brackets are secured to the front element of the frame.

[037] In a further embodiment, the frame comprises guide means extending from the rear element, and adapted to locate below a rear shocktube of the vehicle. Preferably, the guide means is adapted for retaining engagement with the shock tube.

[038] According to a third aspect of the invention, there is provided a kit for facilitating fitment of an alternative suspension device to replace a first suspension device in a body-on-frame vehicle suspension, the kit comprising a structure for installation in a body-on-frame motor vehicle by removable mounting to a chassis rail of the vehicle by fastening means, and locating means for connecting to the structure, in operative orientation, a second, alternative suspension device.

[039] In an embodiment, the locating means includes engagement means engageable with the alternative suspension device. The engagement means preferably comprises retainer means.

[040] The retainer means may in an embodiment comprise clamping means. The clamping means is preferably adapted for receiving and clamping against the structure a portion of an alternative suspension device.

[041] In a preferred embodiment, the clamping means comprises a retention plate and fastening means for fastening the plate to the structure, while applying clamping force to said portion of the alternative suspension device.

[042] In a further preferred form of the invention, the structure comprises a mounting plate against which the alternative suspension device is located in operative orientation.

[043] In a still further preferred form of the invention, the mounting plate includes the locating means.

[044] In a further preferred form of the invention, the structure further includes mounting brackets for a pair of shock absorbers. Preferably, the shock absorber mounting brackets are located fore of the locating means.

[045] Still further, according to this aspect, the kit includes a mounting bracket for connection to a control arm. Preferably, the control arm is a lower control arm.

[046] In a preferred form of the invention, the control arm mounting bracket is adapted to be secured to a chassis rail of the vehicle.

[047] In an embodiment, said mounting bracket is generally U-shaped, having opposed plates and a connecting bridge element. In use, the bridge element straddles the chassis rail with the plates extending to contain, in a gap defined between them, a portion of the chassis rail. The kit may include suitable fastening means for fastening the control arm mounting bracket to the rail. Preferably the fastening means comprises screw-threaded bolt means and complemental retainer means.

[048] The kit extends optionally to includingone or more of upperand lowercontrol arm components suited for a vehicle to in which the structure is to be installed.

[049] In a further aspect of the invention, there is provided a kit for facilitating fitment of an alternative suspension device to replace a leaf spring in a vehicle suspension, the kit comprising two or more frame components and connecting means rendering the frame components connectable to each other to form a framelike structure for installation in a motor vehicle by removable mounting to a chassis rail of the vehicle by fastening means, and locating means for connecting to the structure, in operative orientation, an alternative suspension device.

[050] In an embodiment, the locating means includes engagement means engageable with the alternative suspension device. The engagement means preferably comprises retainer means.

[051] The retainer means may in an embodiment comprise clamping means. The clamping means is preferably adapted for receiving and clamping against the structure a portion of an alternative suspension device.

[052] In a further preferred form of the invention, the frame components when connected, define a structure comprising a mounting plate against which the alternative suspension device is located in operative orientation.

[053] Still further, according to this aspect, the kit includes a mounting bracket for connection to a control arm. Preferably, the control arm is a lower control arm.

[054] The kit extends optionally to including one or more of upper and lower control arm components suited for a vehicle to in which the structure is to be installed.

Brief description of drawings

[055] In order that the invention may be readily understood, and put into practical effect, reference will now be made to the accompanying figures. Thus:

Figure 1 is a schematic bottom view of a preferred embodiment of the assembly of the invention without an alternative suspension device installed.

Figure 2 is a schematic rear elevation of the assembly of Figure 1 with a coiled spring suspension device installed as an example of an alternative suspension device.

Figure 3 is a schematic side view of the assembly of Figure 1.

Figure 4 shows, in perspective view, an embodiment of the spring housing structure of this invention being installed.

Detailed description of an embodiment of the invention

[056] Referring to Figures 1, 2 and 3, in schematic elevation views of this invention, the alternative suspension device support structure is generally denoted by the number 10. The support structure is in the general form of a frame 12, to which are secured support plates 14, 14' adjacent to opposing side panels 16, 16'. To the support plates are attached the alternative suspension device, in this embodiment being suspension springs, to be elaborated on below. However, other examples of suspension devices known in the art may serve as the alternative suspension device without departing from the scope of the invention.

[057] The frame is sized to fit between the chassis rails of the vehicle to be retrofitted. Frames are able to be produced to fit different makes and models of body on-frame vehicle to meet demand. The frames in a preferred embodiment are conveniently sized also to be installed between the chassis rails in a position between the mounting brackets, to which the leaf springs being replaced were attached at their front and rear ends. However, the frame structure may in other embodiments be adapted for installation when they overlap the locations of the vacated mounting brackets.

[058] Each panel 16 has a side lip 18, 18', which extends generally perpendicularly to the plane of the panel. As is seen in Figure 2, the lip 18, 18' abuts the lower surface of the chassis rail 22, 22'. This formation provides two perpendicular and adjacent surfaces that, when the support frame has been installed, abut the opposing under- and inside- surfaces of the chassis rail, providing improved stability of the installation against movement relative to the chassis rails.

[059] The side panels of frame 12 are disposed generally parallel to each other and are defined by angled plates as shown in Figure 3 with an angle 20, 20 to complement the longitudinal profile of the chassis rails (partially shown as 22, 22') of the vehicle (remainder not shown) to which the sprung suspension of this example is to be retrofitted.

[060] At each of their front and rear ends, the support plates are welded to transverse frame elements 24 - disposed at the forward end of the frame - and 26 (at the rearward end). The frame elements 24, 26 are themselves welded to the side panels 16, 16' to produce a sturdy framework. In an exemplary embodiment in which the frame is provided in a dissembled kit form, the frame elements and side panels are provided with suitable tabs and flanges for bolting together.

[061] The frame 12 is bolted to the chassis rails of the receiving vehicle, using bolt receiving apertures 28 in its side panels 16, as shown in Figure 3.

[062] Support plate 14, 14' has a formation for facilitating attachment of one end of the coiled suspension spring 30, 30' in Figure 2. As shown in Figure 1 at 44, 44' where the coil springs are shown removed from position, the formation comprises a set of apertures in plate 14, 14'. The centrally located aperture receives an end portion of the spring 30, 30' and a retainer plate 46, 46' is placed over the first loop of the coil and bolted in place against plate 14, 14', using bolts or a U-bolt through the outer two apertures, to secure the spring in operative position. The distal end of the spring (not shown) is connected in conventional manner to the rear axle (not shown). Appropriate modifications may of course be made to the formation for receiving, for example, an air bag suspension unit, within the scope of the present invention. In a further embodiment, modifications to the formation are provided for accommodating both a coiled spring and an air bag unit.

[063] The frame also has attached to it a pair of mounting brackets 32, 32' to which the upper control arms (not shown) of the vehicle are connected by bolts (not shown) which pass through apertures centred on the axial broken line 34.

[064] In this embodiment, attached to the low side of the frame at the rear transverse bar 26 is a mounting bracket 36 to which the Panhard rod (or track bar), which is connected to the differential (not shown), is pivotally connected through access port 38, to be supported by suitable bolts passing through the bolt holes marked by the axial line 40.

[065] A second pair of mounting brackets 42, 42' are provided for receiving and connecting the shock absorbers of the rear wheels (not shown). Depending on the type of shock absorbers used in different vehicle models, other mounting means may be provided within the scope of this invention, for example an inclined receiving socket for a pin type shock absorber.

[066] It will be appreciated that the relative positions of the sets of mounting brackets and bolt securing apertures described above may be varied for different body on-frame and ladder frame vehicles and their particular suspension layouts; for example, those for the Mitsubishi Pajero will differ from those for the Toyota Prado series and from those for the Nissan Navara platform, while remaining within the scope of the invention.

[067] In the embodiment of Figure 1, the support frame 12 is located between forward 48, 48' and rear 50, 50' pairs of mountings for the leaf springs that the invention would replace. Preferably the rear transverse bar element 26 is located to abut the rear shock tube, 52, with extending, welded retainers 54 helping to hold these two components closely together for added stability.

[068] In Figure 4 the assembly 10 is shown from below and to the rear, ready to be installed in operative position, having been correctly orientated to be raised into position between the chassis rails 60, 60' of the receiving vehicle (shown by the broken lines). At this point in the process of leaf spring replacement, the leaf springs have already been removed from their mounting brackets, the rear pair of which are shown (62, 62'). These brackets and the chassis rails are not part of the invention, and are shown conceptually for convenience and context.

[069] In this embodiment, the frame kit further comprises a separate pair of mounting brackets for attachment to the chassis rails aft of the frame itself. Only one of the pair is shown, marked 70. These brackets provide means for connecting the lower control arms of the vehicle to the rail and are used in instances when the installation of the frame necessitates relocation of the connecting points for the lower control arms.

[070] Each bracket comprises opposed supporting plates 72, 72' spaced apart by a bridging joiner piece 74. The arrangement of the plates in spaced relationship defines a gap 76 into which chassis rail is located when the bracket is placed to straddle the rail, by moving it in the direction generally indicated by arrow 80. The bracket is secured to the chassis rail by means of bolts being passed through the holes provided 78 and fastened by suitable nuts.

[071] For vehicles in which the rear leaf sprung suspension does not include control arms for limiting axle movement, the kit includes a pair of lower control arms. These are adapted and selected for the particular vehicle to be retrofitted. In other embodiments, the control arms may be purchased as optional extras. The control arms are connected to their respective bracket 70 at connection socket 82 using a rubber bushing. The opposite end of the control arm is connected to the axle or the wheel upright, as is conventional.

[072] In vehicles having lower control arms, the kit for these vehicle models would omit the control arms. Control arm mounts separate from the spring support frame are found to be needed for wagon-type four-wheel drive vehicles to accommodate shorter control arms and differences in the lengths of spring leaf assemblies between models.

[073] It is usual in leaf spring suspensions for the front part of the leaf spring to act as a control arm, holding the axle in line to control wheelbase and maintain proper tracking. With the leaf spring removed and replaced and the control arm functionality now lacking, a new control arm assembly will need to be installed. In order to install a control arm mounting bracket successfully, its position on the chassis rail needs to be determined, taking into account the control arm length.

[074] When the supporting assembly structure 12 has been located in position between the chassis rails, it is secured in position using threaded bolts and nuts or other suitable fastening means. With the chassis suitably raised, the coil springs in this example are connected to the support plates by inserting the upper end into the middle aperture 44, 44' in figure 1 and clamping the proximate length of coil adjacent to the upper end to the plate, using retainer plate 46, 46', and bolting the latter in place, as referred to previously. The lower end of the spring is secured to the axle and the vehicle is lowered to allow its weight to be borne on the springs. It will be appreciated that the support assembly is urged upward so that the upper surfaces of the side lips are urged against the bottom surfaces of the respective chassis rails.

[075] In a further embodiment of the invention, the Panhard mounting bracket is dispensed with, in favour of triangulated arms, or functional equivalents.

[076] According to an alternative embodiment, the retainer plates 46, 46' for securing the coils are replaced with a boss with which to locate the top end of the coil spring. Suitable retainers are provided in the case where air bags are used instead of coiled springs. These are included in embodiments of the kit intended for fitment of air bags units alone or in combination with coil springs.

[077] The shock absorber mounts may also be adapted to fit alternative forms of shock absorber, for example pin-style shocks.

[078] A major advantage of this invention is that it may be exercised by the Do-It Yourself enthusiast with minimal tools and workshop facilities. There is no need to send the vehicle to an engineering workshop for the conversion to be carried out. However, for safety reasons, it is desirable that the appropriate equipment be available and used.

[079] These embodiments merely illustrate particular examples of the method, kit and product of the invention providing a coil spring support assembly for retrofitting to a leaf-sprung vehicle. With the insight gained from this disclosure, the person skilled in the art is well placed to discern further embodiments by means of which to put the claimed invention into practice.

Claims

REPLACEMENT SHEET 13 Claims

1. A method of replacing a leaf spring with an alternative suspension device in the suspension of a body-on-frame motor vehicle having left and right chassis rails that extend generally horizontally and in parallel from the front to rear of the vehicle, the method comprising steps of:

• Providing a body-on-frame vehicle;

• Removing the leaf springs from the vehicle;

• Locating between the chassis rails a pre-assembled structure onto which an alternative suspension device to replace the removed leaf springs is mountable, the structure including a generally rectangular crossmember that, when the structure has been operatively located, extends from the left chassis rail to the right chassis rail and includes left and right side sections flanking a central zone, each side section having:

a. a flat surface portion and a formation to accommodate locating and mounting to it of an alternative suspension device, and

b. an outer peripheral edge zone distal from the central zone and

c. a panel extending orthogonally from the edge zone, the panel being adapted for bolting in use to the chassis rail with which it is associated;

• Bolting the side panels of the structure to the rails to be operatively and removably fastened thereto; and

• Providing the alternative suspension devices and fitting them to the left and right side flanking sections of the cross-member in operative orientation.

2. The method of claim 1, wherein the panels include lip formations that extend below the respective chassis rails.

3. The method of claim 2 including urging the structure upward between the chassis rails until the lip formations abut the rails, preventing further relative upward movement, and securing said structure to the rails.

REPLACEMENT SHEET 14

4. A suspension assembly for installation in a body-on-frame motor vehicle equipped with a first suspension device comprising leaf springs and having left and right chassis rails that extend generally horizontally from the front to rear of the vehicle, the assembly comprising a removable, bolt-in structure onto which an alternative suspension device to replace the leaf springs is mountable, the structure including a generally rectangular crossmember that, when the structure has been operatively installed between the chassis rails, extends from the left to the right chassis rail and includes left side and right side sections flanking a central zone, each side section including:

• a flat surface portion and a formation to accommodate location and mounting to it of an alternative suspension device, and

• an outer peripheral edge zone distal from the central zone, and

• a panel extending orthogonally from the edge zone, the panel being adapted for bolting in use to the chassis rail with which it is associated.

5. The suspension assembly of claim 4, wherein the left and right side panels are adapted for being bolted to the respective chassis rails at a location on an inside surface of the rail with which it is associated and which faces an inside surface of the other rail.

6. The suspension assembly of claim 5, wherein the side panels have laterally extending lips for bringing into abutment with an underside portion of the chassis rails.

7. A suspension assembly according to any one of claims 4 to 6, wherein the flanking section to which the alternative suspension device is mountable includes a mounting plate.

8. A kit for facilitating fitment of an alternative suspension device to replace a first suspension device comprising leaf springs in the suspension of a body-on-frame motor vehicle having left side and right side chassis rails, wherein the kit comprises a support structure for removable installation between the chassis rails of said vehicle, the structure including a generally rectangular crossmember that, when the structure has been operatively installed, extends from the left to the right chassis rail and includes respective left side and right side sections flanking the central zone, each flanking section having:

REPLACEMENT SHEET 15

• a flat surface portion and a formation to accommodate locating and mounting to it of an alternative suspension device,

* an outer peripheral edge zone distal from the central zone, and

• a panel extending orthogonally from the edge zone, the panel being adapted for removable bolting to the chassis rail with which it is associated.

9. The kit of claim 8, wherein the flanking sections include a mounting plate against which the alternative suspension device is locatable in operative orientation.

10. The kit of claim 8 or claim 9, wherein the structure is provided in preassembled form ready for being bolted to the chassis rails.

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