Motorcycle swing arm support assembly

The invention relates to a swing arm support assembly for a motorcycle and a method for assembling a motorcycle having such a swing arm support assembly.

It is known to mount a transmission case to a swing arm and frame with a single elongated bolt member. In the past, the motorcycle drive belt has defined a loop around the elongated bolt member. In such prior art assemblies, the elongated bolt member had to be removed entirely from the transmission case to drop the transmission case and provide clearance for removal and replacement of the drive belt.

In the past, motorcycles have been manufactured by holding the swing arm in position while the transmission case is mounted to the swing arm and the motorcycle frame. The swing arm has typically been held in place by an outside force, such as manually or with a machine, until the bolt member can be inserted through the swing arm, frame, and transmission case.

The present invention provides a motorcycle having a frame, swing arm, a transmission case, an elongated pivot member pivotally mounting the swing arm and transmission case to the frame, a removable spacer disposed on the elongated pivot member, and a drive member defining a closed loop about the elongated pivot member. Preferably, the spacer is disposed between a pivot mounting portion of the frame and the transmission case. The spacer may be disposed within the closed loop defined by the drive member.

The invention also provides a method for removing a drive member from a motorcycle. The method includes the steps of removing a spacer and removing the drive belt while maintaining the transmission case substantially in the operating position. The method may include partially removing a pivot member that supports the transmission case and the spacer, and then removing the spacer from the pivot member. The method may include removing the spacer from between the transmission case and the frame prior to removing the drive member.

The invention also provides a method for assembling a motorcycle having a frame and a swing arm. The method includes aligning the swing arm with the frame, inserting a bushing through both the swing arm and the frame to pivotally connect the swing arm to the frame, and inserting an elongated pivot member through the bushing. Preferably, the bushing includes an elongated portion, and the method includes extending the elongated portion through a portion of the swing arm and the frame. The method may also include positioning a portion of the swing arm adjacent an inwardly-facing surface of the frame and extending the bushing through the swing arm and then through the frame.

Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings.

FIG. 1 is a left side elevational view of a motorcycle embodying the present invention.

FIG. 2 is an exploded perspective view of a rear portion of the motorcycle with some components removed or partially broken away for the purpose of illustration.

FIG. 3 is a perspective view of the bottom of a portion of the motorcycle with a portion of the frame removed for the purpose of illustration.

FIG. 4 is a right side elevational view of the rear portion of the motorcycle with some components removed and a portion of the frame broken away for the purpose of illustration.

FIG. 5 is a cross-section view of the swing arm support assembly taken along line 5 — 5 in FIG. 4 .

Before one embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The use of “consisting of” and variations thereof herein is meant to encompass only the items listed thereafter. The use of letters to identify steps of a method or process is simply for identification and is not meant to indicate that the steps should be performed in a particular order.

FIG. 1 illustrates a motorcycle 10 including a frame 14 . Mounted to the frame 14 are a seat 18 , a fuel tank 22 , front and rear wheel assemblies 26 , 30 , an engine 34 , and a transmission case 38 . The illustrated engine 34 is V-type two-cylinder four-stroke engine including first and second cylinders. The invention may, however, be embodied in a motorcycle having a non-V-type engine, or an engine with one cylinder or more than two cylinders.

FIG. 2 better illustrates the motorcycle frame 14 . The frame 14 includes a backbone portion 42 , a pair of front members 46 , a pair of lower members 50 that are substantially parallel to each other, and a pair of rear portions 54 that include a pair of pivot mounting portions 62 having generally horizontal, axially-aligned bores 66 extending therethrough.

Referring again to FIG. 1, the transmission case 38 includes the transmission of the motorcycle 10 . An engine crankshaft (not shown) drives the transmission main shaft (not shown). The crankshaft and main shaft are concealed by a cover 70 . The transmission also includes an output shaft that drives the rear wheel 30 through a belt or other drive member 74 (also shown in FIG. 5 ). Although the illustrated motorcycle 10 includes a left-side-only drive system, the invention may be modified to be embodied in motorcycles having other types of drive systems, such as right-side or chain drive systems.

As shown in FIGS. 2 and 4, the top portion of the transmission case 38 is mounted to the backbone portion 42 of the frame 14 through an upper support 78 and fasteners. The bottom portion of the transmission case 38 is mounted to the frame 14 with suitable mounting assemblies 82 . The rear of the transmission case 38 includes a transmission mounting portion 86 that has an elongated bore 90 extending therethrough (FIG. 5 ). The front of the transmission case 38 is mounted to the engine 34 along a substantially vertical interface with substantially horizontally-oriented bolts. Other types of engine-transmission interfaces may be used, such as a horizontal interface with substantially vertically-oriented bolts.

FIGS. 2 and 4 also illustrate the swing arm assembly, which includes a swing arm 94 and a pair of generally parallel shocks 98 pivotally mounted to the swing arm 94 . The swing arm 94 includes rear wheel mounting portions 102 where the rear wheel is mounted for rotation. The swing arm 94 also includes a pair of swing arm mounting portions 106 that each have an elongated bore 110 extending through them (FIG. 5 ). The swing arm mounting portions 106 are adapted to be disposed on either side of, and in spaced relation to, the transmission mounting portion 86 , and with the respective bores 110 , 90 axially aligned.

A swing arm support assembly is best illustrated in FIGS. 2 and 5. The assembly includes a pair of bushings 114 having a flange portion 118 , an elongated sleeve portion 122 , and a bore 124 extending therethrough. The swing arm support assembly further includes a pair of spacer members 126 having bores 128 , an elongated pivot member (e.g., a bolt 130 ), a pair of washers 134 , and a nut 138 . A bearing 142 is provided in each of the bores 110 of the swing arm mounting portions 106 . The swing arm support assembly pivotally mounts the swing arm 94 adjacent to an inwardly-facing surface 146 of the pivot mounting portion 62 , and supports the rear portion of the transmission case 38 in an operating position relative to the frame 14 . The sleeve portions 122 of the bushings 114 extend through the bearings 142 in the swing arm mounting portions 106 and through the bores 66 in the pivot mounting portions 62 such that the flanges 118 abut the bearings 142 or an inner surface of the swing arm 94 . The bolt 130 extends through the bores 66 , 110 , 124 , 128 , 90 in the pivot mounting portion 62 of the frame 14 , the swing arm mounting portion 106 , the bushings 114 , the spacers 126 , and the transmission mounting portion 86 . The washers 134 are positioned as shown at either end of the bolt 130 against an outwardly-facing surface of the frame's pivot mounting portion 62 , and the nut 138 is secured to hold the bolt 130 in place.

The shocks 98 have been omitted from FIG. 2 to better illustrate the frame 14 in that view. FIG. 3 illustrates the shocks 98 and how they are mounted to a cross-member 148 welded to the lower portions 50 of the frame. The shocks 98 absorb some of the vibrations and forces transmitted through the rear wheel assembly 30 swing arm 94 .

The drive belt 74 defines a closed loop around the spacer 126 on the left side, as shown in FIGS. 1 and 5. When it is necessary to remove and replace the drive belt 74 , the left side washer 134 and the nut 138 are removed from the bolt 130 , and the bolt 130 is pulled out far enough to permit removal of the left side spacer 126 . The drive belt 74 may then be removed and replaced while the bolt 130 supports the transmission case 38 in the operating position. Once the belt 74 has been replaced, the spacer bore 128 is aligned with the bolt 130 , and the swing arm support assembly is returned to the condition illustrated in FIG. 5 .

It should be noted that alternatives to the illustrated embodiment are contemplated. For example, the spacer 126 may be disposed other than on or around a portion of the bolt 130 . The main purpose of the spacer 126 is to prevent or limit lateral movement of the transmission case 38 , and to be removable to permit removal of the drive belt 74 . In this regard, the spacer 126 may be positioned anywhere as long as it serves these purposes. For example, the spacer 126 may be disposed outside the loop, as long as it is removable to permit removal of the drive belt 74 .

The illustrated swing arm support assembly facilitates assembly of the motorcycle 10 . During assembly, the swing arm assembly (e.g., the swing arm 94 and shocks 98 ) is positioned adjacent the inwardly-facing surfaces 146 of the pivot mounting portion 62 of the frame 14 , as shown in FIG. 2 . Then the bushings 114 are inserted from the inside to temporarily couple the swing arm 94 and frame 14 . Once the bushings 114 have been inserted, there is no further need to support the swing arm 94 , because the bushings 114 hold the swing arm 94 in alignment with the frame 14 . Then the transmission case 38 and spacers 126 are positioned in the operating position as shown in FIG. 2, and the bolt 130 is inserted and secured with the washers 134 and nut 138 . At this point, the transmission case 38 is properly located with respect to the frame 14 , and the upper and lower portions of the transmission case 38 may be mounted as shown in FIGS. 2 and 4. This method of assembling a motorcycle 10 does not require machining of the frame 14 or any support surface for the transmission case 38 .