This application claims the benefit under 35 U.S.C.119(e) from U.S. provisional application Serial No. 60/684,585, filed May 26, 2005.

FIELD OF THE INVENTION The present invention relates to a conversion kit and the method of use thereof for converting a two wheeled motorcycle to a three wheeled motorcycle.

BACKGROUND

In many instances it is desirable to convert a two-wheeled motorcycle into a three-wheeled motorcycle. For example a three-wheeled motorcycle is desirable when persons wish to enjoy the open ride of a motorbike but with greater stability.

Various examples of three-wheeled motorcycles are disclosed in the following US patents: 5,499,689 to Johnson, 4,325,449 to D'Addio et al., 4,449,602 to Dittmann, Jr., 5,692,5577 to Dornbusch et al., 5,236,060 to Huber, 4,287,960 to

McConnell, 4,437,535 to Winchell et al., 5,899,291 to Dunmais, 4,905,787 to

Morin, 1 ,271 ,553 to Elliott, 1 ,933,102 to E. P. Du Pont et al., 1 ,956319 to E. P. Du

Pont et al., and 5,785,141 to Breitkreutz et al.

In general prior art kits for converting a two-wheeled motorcycle into a three-wheeled motorcycle have a poor finished appearance which is not consistent with existing components of the original motorcycle. Furthermore known systems generally require complex mounting for proper alignment of the dual rear wheels with the direction of travel of the motorcycle, as well as proper alignment of the drive train and the suspension. Many attempts have been made to provide generic kits which can be adjusted to various different types of motorcycles, however, the generic nature of these kits requires different types of adaptive connectors or numerous additional adjustments to be made once the kit is installed

in order to function properly. The use of extra connectors and subsequent adjustments is time consuming and difficult to install. In addition prior art kits typical require either a poorly performing drive train without a differential or a complex drive shaft conversion is required. SUMMARY OF THE INVENTION

According to one aspect of the invention there is provided a method of converting a motorcycle having a frame with a pivot bolt assembly for pivotally supporting a rear wheel swing arm assembly thereon, the method comprising: providing a replacement swing arm frame extending in a longitudinal direction between a forward end and a rearward end thereof, the rearward end comprising a pair of spaced apart frame members extending in the longitudinal direction; pivotally connecting the front end of the swing arm frame to the pivot bolt assembly of the motorcycle; connecting the swing arm frame to an existing rear suspension of the motorcycle; supporting first and second axles rotatably on the frame members respectively for rotation about a common axis lying perpendicularly to the longitudinal direction; connecting a pair of wheels to the first and second axles respectively, connecting brakes to the first and second axles respectively; connecting the first and second axles with a drive motor of the motorcycle; and adapting brake mounts and shock mounts of the replacement swing arm frame for mounting suspension and brakes available from the same manufacturer as the motorcycle being converted.

The kit according to the present invention is configured and

specifically arranged in each embodiment for connection to one particular model of one brand of motorcycle to minimize any subsequent adjustments required when installed on the motorcycle. The replacement swing arm frame includes mounting locations for mounting the existing components of the motorcycle and additional parts available from the same manufacturer as the original motorcycle for installing all of the components including the brake callipers, the brake rudders, the shocks and chain drive of the existing motorcycle. Replacement parts for any of these components are thus available from the original manufacturer of the motorcycle. In particular, the use of a chain driven sprocket on the differential which is in alignment with the existing drive sprocket of the motorcycle permits the use of a conventional chain connection therebetween to minimize complexity of the conversion.

According to a second aspect of the present invention there is provided a conversion kit for a motorcycle having a frame with a pivot bolt assembly for pivotally supporting a rear wheel swing arm assembly thereon, the kit comprising: a replacement swing arm frame extending in a longitudinal direction between a forward end and a rearward end thereof, the forward end being adapted for pivotal connection to the pivot bolt assembly of the motorcycle and the rearward end comprising a pair of spaced apart frame members extending in the longitudinal direction; shock mounts on the swing arm frame for connection to a rear suspension of the motorcycle; first and second axles rotatably supported on the frame members respectively for rotation about a common axis lying perpendicularly to the longitudinal direction; a pair of wheels for connection to the first and second axles

respectively; brakes for connection to the first and second axles respectively; and a differential operatively connecting the first and second axles, the differential including a chain driven sprocket for chained connection to a Chain drive sprocket of the motorcycle.

According to a further aspect of the present invention there is provided a method of converting a motorcycle having a frame with a pivot bolt assembly for pivotally supporting a rear wheel swing arm assembly thereon, the method comprising: providing a replacement swing arm frame extending in a longitudinal direction between a forward end and a rearward end thereof, the rearward end comprising a pair of spaced apart frame members extending in the longitudinal direction; pivotally connecting the front end of the replacement swing arm frame to the pivot bolt assembly of the motorcycle; connecting the swing arm frame to a rear suspension of the motorcycle; supporting first and second axles rotatably on the frame members respectively for rotation about a common axis lying perpendicularly to the longitudinal direction; connecting a pair of wheels to the first and second axles respectively; connecting brakes to the first and second axles respectively; providing a differential including a chain driven sprocket; connecting the first and second axles with the differential; and connecting the chain driven sprocket with a chained connection to a chain drive sprocket of the motorcycle.

When a housing surrounds the axles and the differential, the housing

is preferably fixed between the frame members.

The differential preferably comprises an outer housing fixed relative to the frame and a rotatable housing carried therein within which the first and second axles are operatively connected wherein the chain driven sprocket is supported about the rotatable housing for rotation therewith.

Each frame member may comprise a pair of parallel and spaced apart tubes supporting the first and second axles therebetween for sliding movement in the longitudinal direction of the frame.

Fender mounts may be supported on the swing arm frame for piviotal movement with the axles carried on the swing arm frame relative to the motorcycle frame. The fender mounts may be supported on a mounting plate carried by the axle housing commonly with brake mounts for the brakes.

A chain tightener may also be carried on the swing arm frame. In the illustrated embodiment, the forward end of the swing arm frame is adapted for pivotal connection to the existing pivot bolt assembly of a Harley Davidson™ motorcycle.

Two embodiments of the invention will now be described in conjunction with the accompanying drawings in which: BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view from a front end of a first embodiment of the swing arm frame.

Figure 2 is a perspective view from a rear end of the first embodiment.

Figure 3 and Figure 4 are respective top plan and side elevational views of the frame according to Figure 1.

Figure 5 is a sectional view along the line 5-5 of Figure 4.

Figure 6 is a rear elevational view of the frame according to Figure 1 ,

Figure 7 is a perspective view from a front end of a swing arm frame according to a second embodiment.

Figure 8 is a perspective view from a rear end of a swing arm frame according to the second embodiment. Figure 9 and Figure 10 are respective top plan and side elevational views of the frame according to Figure 7.

Figure 11 is a sectional view along the line 11-11 of Figure 10. Figure 12 is a rear elevational view of the frame according to Figure 7. In the drawings like characters of reference indicate corresponding parts in the different figures. DETAILED DESCRIPTION

Referring to the accompanying Figures there is illustrated a kit generally indicated by reference numeral 10. The kit 10 is particularly suited for a motorcycle (not shown) of the type having a frame including a rear wheel assembly pivotally supported on a pivot bolt assembly of the motorcycle.

The motorcycle for which the conversion kit is suited for, is conventional and includes a rear suspension coupled between the rear wheel assembly and the frame along with a chain connection between a drive sprocket of the motorcycle and the rear wheel. The kit 10 is intended to replace the single rear wheel assembly with dual rear wheels in a convenient manner which permits the single rear wheel assembly to be reinstalled at a later time as desired. Though two embodiments are shown in the accompanying figures, the common feature of each will first be described herein. The kit generally comprises a replacement swing arm frame 20 extending in a longitudinal direction between a front end 22 and a rear end 24. In the mounted position, the longitudinal direction is intended to be aligned with a

direction of travel of the motorcycle.

A transverse aperture 26 is defined at the front end which is adapted for alignment with the pivot bolt assembly on the motorcycle. The transverse aperture 26 is oriented perpendicularly to the longitudinal direction for laterally receiving a pivot shaft therethrough which secures the swing arm frame 210 for pivotal movement about a horizontal axis relative to the motorcycle frame.

The frame 20 includes two frame members 28 which extend longitudinally from the front to the rear end 24. The frame members are sp$ced apart at the front end and initially extend rearwardly at an outward incline iat a forward incline portion 30 thereof. Towards the rear end of the frame, the fr&me members 28 are spaced further apart than at the front end and extend parallel to the longitudinal direction and to each other over a main portion 32 of the leiiigth thereof.

Each frame member 28 comprises two vertically spaced apart tubes 34 which are parallel to one another. The tubes are joined with one another at the inclined portion 30 to maintain the spacing thereof along the main portion 32.

A shock mount 36 in the form of transverse mounting apertures $re also provided adjacent the front end 22 of the swing arm frame 20. Location of the shock mount 36 varies depending upon the particular model of motorcycle which the frame is intended to be installed on so that the shock mount 36 can be located in the same position as the shock mount on the stock rear wheel swing anm assembly of the motorcycle. The existing shocks can thus be coupled to the shoφk mount.

An anchor 28 is provided on each frame member 28 at a forward end of the main portion 32 to span between the tubes 34 which define the frame member. The anchor 38 includes an annular portion fixed onto each tube 34 respectively with a stem extending therebetween. An axial mounting block 40 is

similarly mounted to span the tubes 34 of each frame member 28 and serves to mount first and second axles 42 and 44 on the frame members 28 respectively. Each block 40 includes a top channel 46 and a bottom channel 48 which receives the tubes 34 of the frame member therein. Clamping members 50 are provide at each of the top and bottom sides for clamping the tubes within the channel 46 and 48 respectively.

An adjustment screw 52 is connected between the anchor 38 and the mounting block 40 so that the longitudinal position of the each of the mounting blocks can be adjusted using the adjustment screw 52 prior to being clampepl down. Once the block is set in place, the top and bottom clamping members 50 are clamped into place using respective threaded fasteners.

Each of the first and second axles are rotatably carried within a respective axle housing 54 which is in fixed connection with the respective mounting block 40 within which it is carried. The axle housings 54 are thus supported by the mounting blocks 40 between the tubes 34 of the frame members

28 respectively.

The axle housings 54 are rigidly connected by a casing 56 of a differential 58 supported therebetween. The two axle housings and the casing φf the differential thus form a continuous housing which is rigidly connected between the opposing frame members 28 to provide structural support at the rear of the frame 20. The first and second axles are thus supported for rotation about a common longitudinal axis lying perpendicular to the longitudinal direction of the frame 20 and the tubes 34.

The interior ends of the axles 42 and 44 housed within the axle housings 54 each include an end face gear 60 such that the gears are confronting one another and mesh on opposing sides of a pair of idler gears 62 therebetween.

The idler gears 62 are diametrically opposite one another for rotation about a

common shaft 64 extending therebetween in a manner similar to conventional differentials. The common shaft 64 lies diametrically in relation to and rotates about the common axis of the first and second axles 42 and 44 along with a surrounding rotatable housing 66 which carries the shaft 64. The rotatable housing 66 includes a toothed outer periphery whi4h defines a driven sprocket 68 which lies in a common plane with the drive sprocket of the motorcycle. Suitable apertures 70 are provided in the casing 56 of trie differential for receiving a chain connection therethrough which connects the driven sprocket 68 to the drive sprocket of the motorcycle. A chain tightener mechanism is coupled to the casing 56 at an outer side of the differential. The tightener 72 generally comprises an idler gear 74 supported on a pivot arm 76 which is biased in a direction to urge the idler 74 against the chain connecting the driven sprocket with the drive sprocket of the motorcycle in a manner so as to add tension to the chain. The axle housing extends through the mounting blocks from an inner end spanning between the mounting blocks and the casing of the differential to a!n outer end which projects outwardly beyond the mounting blocks externally of the frame members 28. The outer free ends of the axle housings 54 each include a bolt flange 78 thereon which bolts a suitable upright mounting plate 80 thereon. The mounting plate includes mounting apertures formed therein spaced radially outwardly from the axle housing such that a pair of the apertures defines mounts for brake callipers 82 while an additional pair of the apertures provides mounts fφr a fender 84 which can be mounted thereon for movement with the swing arm anid wheels relative to the motorcycle frame. Spacing of the apertures in the mountinlg plate 80 is arranged to permit original equipment manufactured by the original motorcycle manufacturer so that existing parts can be used.

The first and second axles 42 and 44 project axial beyond the free

ends of the respective axial housing 54 sufficiently for supporting a brake rotor 86 thereon in alignment with the brake clippers 82 and a wheel hub 88 for supporting one of the rear wheels thereon. The swing arm supports the first and second axlφs spaced from the pivot bolt assembly of the motorcycle greater than the rear wheel axle of the original signal rear wheel assembly by approximately 6 inches to improve stability of the motorcycle.

Turning now to the embodiment illustrated in Figures 1 through 6, the swing arm frame 20 as illustrated is particularly suited for attachment to the Soft Tail model of Harley Davidson™ motorcycle. The front end 22 of the frame in this instance includes two vertically oriented plates 90 which are parallel to one another and include centrally located apertures 26 therein in alignment with one another fφr connection to the pivot bolt assembly of the motorcycle. Top and bottom crossbars 92 span between the plates 90 at respective top and bottom ends thereof fφr maintaining the plates parallel and spaced apart from one another. The shock mount 36 in this instance is spaced below the transverse aperture 26 and generally comprises a sleeve which is supported centrally in front of the lowermost crossbar 92.

The tubes 34 forming each of the frame members 28 are initially spaced apart from one another at opposing top and bottom ends of plates 90 so as to taper towards one another over the length of the inclined portion 30 of the frame members. Crossbars 94 span between the tubes 34 of each frame member spaced rearwardly from the transverse aperture 26. The main portion of the tubes extends rearwardly from the crossbars 94, parallel to one another.

Turning now to the embodiment illustrated in Figures 7 through 12, the swing arm frame 20 is particularly suited for mounting on a four speed Sportster model of a Harley Davidson™ motorcycle. In this instance the transversa aperture 26 is defined by a sleeve 96 at the front end of the frame which is

perpendicular to the longitudinal direction of the frame. The two tubes 34 forming each frame member are joined directly one above the other at spaced positions at opposing end of the sleeve 96 at the front end. The tubes 34 of each frame merrjie remain joined through the inclined portion 30 at which point the tubes 34 diverge from one another and are reinforced by respective gussets 98 before spanning rearwardly, parallel and spaced from one another through the main portion of eatjh of the members 28.

The shock mounts comprise a pair of vertical plates 100 mounted dn the inclined portions 30 of the frame members respectively to locate respective mounting apertures therein which are higher than the transverse aperture defined by the sleeve 96.

In both embodiments the rear ends of the frame members 28 projeφt rearwardly beyond the axle housings sufficiently for mounting a bumper at the regr end thereof while still providing clearance for the rear wheels ahead of the bumpeif. Installation of the kit involves removing the original rear wheel assembly from the pivot bolt assembly of the motorcycle so that the swing arφ frame 20 according to the present invention may be installed at the existing pivdt bolt assembly. Mounts are provided on the swing arm frame for reconnecting th^ existing shocks on the shock mounts, connection of brake components including callipers and rotors from the original manufacturer on the respective mounts as well as the use of wheel hubs and a chain drive which also meets specifications of Harley Davidson™ parts to minimize adjustments required upon installation whitø ensuring the finished appearance of the converted motorcycle is consistent with the remaining original components on the motorcycle. Use of original equipment parts ensures that the parts remain readily available for replacement during future maintenance as required.

Since various modifications can be made in my invention as herein;

above described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without department from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.