Abstract:
A vehicle door attachment unit for rotatably and detachably coupling a vehicle door to a vehicle body. The unit may include a bodyside bracket mountable to the vehicle body and having first and second portions with respective first and second apertures, with the first and second portions extending generally away from the vehicle body. A doorside bracket may be mountable to the vehicle door and include a segment with a third aperture, the segment extending generally away from the vehicle door. A retaining mechanism may extend through the third aperture, and through the first and/or second apertures. A fastener may extend through at least one of the apertures and mate with the retaining mechanism to substantially align the first, second, and third apertures. A bearing may be disposed on the retaining mechanism for providing rotational freedom between the retaining mechanism, and the bodyside or doorside bracket.

Description:
BACKGROUND OF INVENTION 
     a. Field of Invention 
     The invention relates generally to hinges for vehicle closure members, and more particularly, to hinges that facilitate removal and installation of vehicle doors for expediting the vehicle assembly process. 
     b. Description of Related Art 
     As is known in the art, removing vehicle doors from a vehicle body during a particular segment of a vehicle assembly process, also known as a “doors off” technique, helps achieve automotive manufacturing efficiency. As opposed to keeping the doors on the vehicle body after initial attachment, this doors off technique provides increased access through door opening areas for facilitating installation of vehicle components, such as vehicle seats. After the doors are removed from the vehicle body on the primary assembly line, the doors may be separately outfitted in an off-line door assembly process. Window systems, door latches, door handles, and trim panels are a few of the exemplary components that can be installed on vehicle doors while removed from the vehicle body. Following this stage, the doors may be reattached to the vehicle body. 
     Many vehicle door-to-body hinges exist that attempt to make attaching, removing, and reattaching doors to the vehicle body as efficient as possible. In general, fewer parts that need to be removed and reattached correlates to better assembly efficiency. Some take-apart hinges allow a door to be detached from the vehicle body after one or more pins, bolts, etc. are removed from the hinge. The door is then lifted off the vehicle body for separate subassembly. Current lift-off hinges are typically made from profile stock or forgings, and are thus generally more costly than stamped hinges. Such profile and forged lift-off hinges cannot cost effectively package a locating pin on a body side bracket of the hinge to enable certain low investment door hang concepts. Conversely, current stamped hinges which incorporate a lift off feature compromise hinge strength or dimensional integrity. 
     Exemplary lift-off vehicle door hinges are disclosed in U.S. Pat. Nos. 4,765,025 and 4,766,643 to Salazar, respectively (Salazar &#39;025 and Salazar &#39;643). Referring to FIGS. 1-3 of Salazar &#39;025 and Salazar &#39;643, whereas the patents disclose the use of cost effective stamped brackets on the upper and lower hinges, the assemblies use a considerable number of fasteners to attach body mounting plate (20), door mounting plate (22), and door (14) to one another and to vehicle (10). Even if only one or two fasteners are used to hold the door in place until final assembly, driving a surplus of fasteners is detrimental to assembly time and component cost. One inefficiency is evidenced through the use of two pivot pins (24, 26) instead of one, which can add assembly and manufacturing time, and component cost. 
     In another exemplary stamped hinge assembly, U.S. Pat. No. 4,881,298 to Turnbull teaches a “separable door hinge” that has intertwining leaves, flanges, and tabs for maintaining the door in a fixed vertical position. One drawback to this separable door hinge is in its design to hold the door in a fixed position in relation to the height of the vehicle body. Referring to FIG. 1 of Turnbull, since the intertwining projections mentioned above, such as lower flange (52) rotating between tab (40) and lower flange (24), are not clamped by a traditional fastener, as shown in FIG. 2, relative movement of flanges (24, 52) during opening and closing of the door causes the intertwining projections to scrape one another. If the components have any free-play, even minimal vertical movement of the door can cause unnecessary fatigue on related components such as the striker member, the door latch, the periphery of the door opening, and the hinge components themselves. If the components are assembled too tightly, friction present during relative movement of the components can cause unnecessary fatigue on hinge components and undesirable noise and vibrations. Yet further, when a door is removed from the vehicle body, the main pivot is not kept intact. 
     Such deficiencies in existing technology make it desirable to provide a durable and robust door-to-body hinge that remains intact when the door is lifted off the vehicle body for separate subassembly. It is further desirable to provide a hinge that uses cost effective stamped components, and minimal joints for attaching, removing, and reattaching a door to a vehicle body. 
     SUMMARY OF THE INVENTION 
     The invention overcomes the drawbacks and deficiencies of the aforementioned hinge designs by providing a vehicle door attachment unit for rotatably and detachably coupling a vehicle door to a vehicle body, where the detachment interface is separate from the functional pivot interface. The unit may include a bodyside bracket mountable to the vehicle body and having first and second portions with respective first and second apertures, with the first and second portions extending generally away from the vehicle body. A doorside bracket may be mountable to the vehicle door and include a segment with a third aperture, the segment extending generally away from the vehicle door. A retaining mechanism may extend through the third aperture, and through the first and/or second apertures. A fastener may extend through one or more of the apertures and mate with the retaining mechanism to substantially align the first, second, and third apertures. A bearing may be disposed on the retaining mechanism for providing rotational freedom between the retaining mechanism, and the bodyside or doorside bracket. 
     For the vehicle door attachment unit described above, the bodyside and/or doorside brackets may be stamped from sheet metal. The unit may further include a collar generally concentric with the first and second apertures and extending between the first and second portions of the bodyside bracket, with the collar dispersing loads that are transmitted between the vehicle door and the vehicle body across the first and second portions of the bodyside bracket. The retaining mechanism may include an angular seat for engaging a chamfered rim adjacent one of the first and second apertures in the bodyside bracket, with the angular seat and chamfered rim facilitating alignment of the vehicle door attachment unit during assembly thereof. The fastener may include external threads and the retaining mechanism may include a cavity with complementary internal threads, with the external threads on the fastener being engageable with and disengageable from the internal threads of the cavity for respectively permitting assembly and disassembly of the vehicle door attachment unit. The unit may further include a locating pin and a locating hole along the bodyside bracket for receiving the locating pin, with the locating hole being oversized to provide the locating pin with a predetermined amount of translational freedom such that the vehicle door is adjustably mountable relative to the vehicle body. The doorside bracket may further include a doorstop disposed generally orthogonal along the segment and engageable with one of the first and second portions of the bodyside bracket to stop rotation of the vehicle door. 
     The invention also provides a vehicle door attachment unit for rotatably and detachably coupling a vehicle door to a vehicle body. The unit may include a bodyside bracket mountable to the vehicle body and having a portion extending generally away from the vehicle body, with the portion having an aperture. A doorside bracket may be mountable to the vehicle door and include a segment extending generally away from the vehicle door, with the segment having a further aperture alignable with the aperture in the portion of the bodyside bracket. A retainer may extend through one or more of the apertures. A fastener may extend through one or more of the apertures and be capable of mating with the retainer to substantially align the apertures. A rotation member may be operatively engaged with the retainer for providing rotational freedom between the retainer and one of the bodyside and doorside brackets. 
     For the vehicle door attachment unit described above, the bodyside and/or doorside brackets may be stamped from sheet metal. The doorside bracket may further include a doorstop disposed generally orthogonal along the segment and engageable with the portion of the bodyside bracket to stop rotation of the vehicle door. The retainer may include an angular seat for engaging a chamfered rim adjacent one of the apertures, with the angular seat and chamfered rim facilitating alignment of the vehicle door attachment unit during assembly thereof. The retainer may be placed within the rotation member and within one of the apertures, with the retainer being configured to retain the rotation member and one of the bodyside and doorside brackets. The unit may further include a locating pin and a locating hole along the bodyside bracket for receiving the locating pin, with the locating hole being oversized to provide the locating pin with a predetermined amount of translational freedom such that the vehicle door is adjustably mountable relative to the vehicle body. The doorside bracket may be attachable to the vehicle door by a fastener. The bodyside bracket may further include ribbed and flanged features for adding structural rigidity to the bodyside bracket. The portion of the bodyside bracket may be substantially parallel with the segment of the doorside bracket. In a particular embodiment, a bottom end of the fastener may be disposed generally adjacent a top end of the retainer. In another embodiment, a bottom end of the retainer may be disposed generally adjacent a top end of the fastener. 
     The invention also provides a method of assembling an attachment unit to rotatably couple a vehicle door to a vehicle body, with the unit having a doorside bracket, a bodyside bracket, a fastener assembly, and a rotation member. The method may include attaching the doorside bracket to the vehicle door, and attaching the bodyside bracket to the vehicle body. The method may further include press fitting a portion of the fastener assembly to retain the rotation member, and the bodyside or doorside bracket, with the rotation member being disposed between the fastener assembly and the doorside or bodyside bracket, being generally concentric to the fastener assembly, and providing rotational freedom between the fastener assembly and the doorside or bodyside bracket. The method may also include coupling the doorside bracket to the bodyside bracket by tightening the fastener assembly. 
     For the method described above, the bodyside and/or doorside brackets may be stamped from sheet metal. The step of attaching the bodyside bracket to the vehicle body may further include placing a locating pin through a locating hole in the bodyside bracket, calibrating location of the pin, attaching the pin to the bodyside bracket, and attaching the bodyside bracket to the vehicle body. 
     The invention yet further provides a method of removing a vehicle door that is rotatably coupled to a vehicle body. The method may include providing one or more attachment units rotatably coupling the vehicle door to the vehicle body, with the attachment unit including a doorside bracket attached to the vehicle door, a bodyside bracket attached to the vehicle body, a fastener assembly coupling the doorside bracket to the bodyside bracket, and a rotation member substantially concentric to the fastener assembly, being disposed between the fastener assembly and the doorside or bodyside bracket, and providing rotational freedom between the fastener assembly and the doorside or bodyside bracket. The method may also include disengaging the fastener assembly so that the doorside bracket is removable from the bodyside bracket, with the rotation member remaining maintained on one of the doorside and bodyside brackets, and lifting the doorside bracket and the door off of the bodyside bracket, with the rotation member remaining maintained on the doorside or bodyside bracket. 
     Additional features, advantages, and embodiments of the invention may be set forth or apparent from consideration of the following detailed description, drawings, and claims. Moreover, it is to be understood that both the foregoing summary of the invention and the following detailed description are exemplary and intended to provide further explanation without limiting the scope of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate preferred embodiments of the invention and together with the detailed description serve to explain the principles of the invention. In the drawings: 
         FIG. 1  is an isometric view of an upper attachment unit for attaching a vehicle door to a vehicle body member, with the attachment unit shown in a generally closed position and including a doorside bracket for attachment to the door and a bodyside bracket for attachment to the body member; 
         FIG. 2  is a side view of the upper attachment unit of  FIG. 1  without three fasteners positioned in the bodyside bracket as shown in  FIG. 1  and the attachment unit shown in the generally closed position of  FIG. 1 ; 
         FIG. 3  is an isometric view of a mirror image attachment unit for use on an opposite side of a vehicle, similar to the unit of  FIG. 1 , with certain components omitted for clarity; 
         FIG. 4  is an exploded side view of the upper attachment unit of  FIG. 1 ; 
         FIG. 5  is an exploded isometric view of the upper attachment unit of  FIG. 1 ; 
         FIG. 6  is a cross-sectional view of the upper attachment unit taken generally along line A-A of  FIG. 1 ; 
         FIG. 7A  is an isometric view of a lower attachment unit used for attaching a vehicle door to a vehicle body member at a second location generally below the upper attachment unit of  FIG. 1 , with the lower attachment unit shown in a generally closed position; 
         FIG. 7B  is an isometric view of a mirror image lower attachment unit, similar to the unit of  FIG. 7A ; 
         FIG. 8  is a cross-sectional view of the lower attachment unit taken generally along line B-B of  FIG. 7A ; 
         FIG. 9  is an isometric view of the upper attachment unit of  FIG. 1 , including the doorside bracket attached to the vehicle door and the bodyside bracket attached to the vehicle body member, with the unit in a disassembled configuration with the door and doorside bracket being lifted off the bodyside bracket and the body member; 
         FIG. 10  is a side view of a doorside bracket attached to the vehicle door, the upper attachment unit disassembled such that the doorside bracket is detached from the bodyside bracket; 
         FIG. 11 , compared to  FIG. 10 , is a side view of a bodyside bracket and body member after disassembling the upper attachment unit; and 
         FIG. 12  is an isometric view of the upper attachment unit of  FIG. 1  with a central bolt and a doorside fastener ready to be installed. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring now to the drawings wherein like reference numerals designate corresponding parts throughout the several views,  FIGS. 1-12  illustrate various views of attachment units used for coupling vehicle doors to a vehicle body such that assembly efficiency and joint robustness are maximized. According to the present invention, the units will hereinafter be generally designated by “upper attachment unit  10 ” and “lower attachment unit  12 .” 
     As shown in  FIGS. 1-6 , upper attachment unit  10  may include a bodyside bracket  14  and a doorside bracket  16 . As shown in  FIG. 6 , bodyside bracket  14  and doorside bracket  16  may generally be coupled by a central bolt  18  that engages a retainer  20  having internal threads  22 . Upper attachment unit  10  may be disassembled for a doors off subassembly by disengaging central bolt  18  from retainer  20 , a process which will be described in detail below. 
     Referring to  FIGS. 1-6  and  9 , bodyside bracket  14  may have a planar section  24  that mates with a vehicle body member  26 . Body member  26  may be a vehicle pillar or may be located adjacent to a vehicle opening. As shown in  FIG. 2 , planar section  24  may include two fastener holes  28  and  30  and a locating hole  32 . In one embodiment, in order to cost effectively form bodyside bracket  14 , bracket  14  may be stamped from a roll of sheet metal, and holes  28 ,  30 , and  32  may be punched at that time. Fastener holes  28  and  30  may receive bodyside fasteners  34  and  36 , which can attach upper attachment unit  10  and hence a vehicle closure member, such as a vehicle door  38  shown in  FIGS. 9 ,  10 , and  12 , to a vehicle body. Fasteners  34  and  36 , in one embodiment, may mate with weld nuts or some other component previously attached to or built into body member  26 . In order to position the vehicle door relative to the vehicle body, locating hole  32  may receive a locating pin  40 , with the operation of locating pin  40  being described in more detail below. In one aspect of the invention, stamping bodyside bracket  14  may be advantageous since it can create sufficient surface area on planar section  24  without the costs associated with machined components. This surface area can be ideal for distributing the load of bodyside fasteners  34  and  36  which may be attached to body member  26 . The surface area can also be beneficial for making holes  28 ,  30 , and  32  large enough to be capable of positioning vehicle door  38  relative to the vehicle body as needed. 
     In order to increase structural rigidity, bodyside bracket  14  may include flanges  42  around a portion of its periphery. In one embodiment, bodyside bracket  14  may have first and second projections  44 ,  46  which are generally orthogonal to planar section  24 . Projections  44 ,  46  may be configured to protrude away from vehicle body member  26  once bodyside bracket  14  is attached to body member  26 . As shown in  FIG. 5 , first projection  44  may contain a larger hole  48  with a chamfered rim  50 , and as shown in  FIG. 4 , chamfered rim  50  may align and mate with a seat  52  on retainer  20  when attachment unit  10  is assembled. First projection  44  may also include a seat  54  which can be seen in  FIGS. 4 and 6 , and once assembled, seat  54  may mate with a conical feature  56  located at one end of a collar  58 . In order to disperse loads between projections  44 ,  46 , collar  58  may be placed therebetween. Another advantage to stamping bodyside bracket  14  is that adequate surface area along first and second projections  44 ,  46  may be created without the costs associated with machined parts. As shown in  FIG. 4 , for second projection  46 , a smaller hole  60  may be vertically aligned with larger hole  48  in first projection  44 . Once attachment unit  10  is assembled, central bolt  18 , including threaded section  62  for engagement with retainer  20 , may extend through smaller hole  60 , through collar  58 , and through larger hole  48 . 
     Referring to  FIG. 1 , although bodyside bracket  14  is shown with two spaced-apart projections  44  and  46 , embodiments may exist in which bodyside bracket  14  takes on a different shape without compromising the functionality of the invention. For example, the space between first and second projections  44 ,  46  may be reduced, or even eliminated, so that only one projection exists. Of course, the dimensions of a single projection may need modification, but such a design may be advantageous when under various packaging constraints. In an effort to minimize weight and material costs, bodyside bracket  14  may be tapered by removing a portion of planar section  24  closest to projections  44  and  46  and reducing the distance between projections  44  and  46 . In yet another example, a ribbed segment  66  of bodyside bracket  14  may be stamped between projections  44  and  46  to stiffen bracket  14 . 
     Referring to  FIG. 3 , similar to upper attachment unit  10  illustrated in  FIG. 1 , mirror image unit  10  of  FIG. 3  may be formed for use on the other side of a vehicle. Doorside bracket  16 , a substantially common part that may be used in both upper attachment unit  10  and lower attachment unit  12  (with minor modifications as discussed below for bracket  128 ), may generally include a horizontal portion  80  connected to a vertical portion  82 , and a doorstop  84 . More specifically, horizontal portion  80  may have an upper surface  86  and a hole  88  extending vertically therethrough, with upper surface  86  including a shoulder  90 . Vertical portion  82  may be attached to a vehicle door, such as door  38  shown in  FIG. 9 . As shown in  FIGS. 3 and 5 , a fastener  92  may be placed through a hole  94  in vertical portion  82  and engage with a mating component (not shown), such as a weld nut on vehicle door  38 . When looking down on upper attachment unit  10  in the  FIG. 3  orientation, doorstop  84  may rotate in a clockwise direction when an attached vehicle door (not shown) is opened, with doorstop  84  contacting first projection  44  to limit opening movement of the door. While doorstop  84  may be used as a primary means of stopping vehicle door rotation, doorstop  84  may also be used in conjunction with other components for stopping door rotation as would be readily evident to those skilled in the art. 
     The assembly of upper attachment unit  10 , particularly how bodyside bracket  14  and doorside bracket  16  function together, will now be described in detail. 
     The assembly of upper attachment unit  10  will be described with reference to  FIGS. 4 and 5  and the fully assembled, cross-sectional view of  FIG. 6  showing assembled unit  10 . As discussed above, in order to clamp bodyside bracket  14  and doorside bracket  16  together, central bolt  18  may engage with internal threads  22  in retainer  20 . Collar  58  may be inserted between first projection  44  and second projection  46 , with conical feature  56  aligning with seat  54  of first projection  44 . Central bolt  18  may then be inserted up through smaller hole  60 , through collar  58 , and through larger hole  48 . 
     Retainer  20 , the upper portion of which in the  FIGS. 4 and 5  orientation is initially an elongated shaft, may be press fitted into its final shape, as seen in  FIGS. 5 and 6 , after a bearing  100  and a non-circular washer  102  have been placed around retainer  20  and this arrangement of components has been placed within hole  88  of doorside bracket  16 . In one embodiment, non-circular washer  102  may be placed above bearing  100  and may serve primarily as an assembly aid. Referring to  FIGS. 4 and 5 , washer  102  may also have a non-circular inset  104  which constrains, particularly after press fitting, mating portion  106  of retainer  20 . With non-circular inset  104 , torque, or counter torque, can be loaded on washer  102  which ultimately transmits the load to mating portion  106  of retainer  20 . This is helpful when rotatably driving central bolt  18  into retainer  20 . In another embodiment (not shown), retainer  20  can be formed without a spherical head  108 , eliminating the need for washer  102 . In any case, after placing this arrangement within hole  88 , as shown in  FIG. 6 , retainer  20  may be press fitted to form spherical head  108 , with pre-formed lip  110  engaging bearing  100  to facilitate pivotal movement of doorside bracket  16 . Thus, bearing  100  may be oriented to provide freedom between doorside bracket  16  and retainer  20  to generally form a rotatable upper hinge  120 . Press fitting retainer  20  to hold bearing  100 , washer  102 , and doorside bracket  16  all in one subassembly allows for a simple lift off procedure on the vehicle assembly line by removal of central bolt  18  from the assembled upper attachment unit  10 , as discussed in detail below. 
     At this point, doorside bracket  16  may be arranged just above bodyside bracket  14 . Alignment aid  112  on retainer  20  may help guide retainer  20  into larger hole  48  in first projection  44  of bodyside bracket  14 . Seat  52  of retainer  20  can mate with chamfered rim  50  along larger hole  48  to further help align retainer  20  with larger hole  48 . Once aligned, as illustrated in  FIG. 6 , central bolt  18  may be driven to engage internal threads  22  in retainer  20  as non-circular washer  102  is held in place. This driving action may clamp bodyside bracket  14  to doorside bracket  16 . As previously mentioned, vehicle hinges are ideally tight joints with high precision to enable smooth rotation over time. One way to achieve high precision in vehicle hinges may require never taking them apart after initial assembly. This drawback with conventional lift off hinges is overcome by upper attachment unit  10  for which after the initial formation of rotatable upper hinge  120 , central bolt  18  can be driven in and out of retainer  20  without rotatable upper hinge  120  coming apart. 
     Lower attachment unit  12  and its assembly will now be described in detail with reference to  FIGS. 7A ,  7 B and  8 . 
     Lower attachment unit  12  may be generally similar to upper attachment unit  10 , except as discussed below. As discussed above, instead of doorside bracket  16 , a modified doorside bracket  128  may be used with lower attachment unit  12 .  FIG. 7A  shows lower attachment unit  12  which may have a bodyside bracket  130 , generally similar to bodyside bracket  14 , with fasteners  132  and  134  extending through two holes (not shown) for attachment to vehicle body member  26 . A mirror image counterpart to lower attachment unit  12  can be seen in  FIG. 7B  for use with an opposite door. Unit  12  may include a planar section  136  for attachment to body member  26 . As with bodyside bracket  14 , bodyside bracket  130  may be cost effectively stamped from rolled sheet metal to avoid the costs associated with machined components. Bodyside bracket  130  may also have first and second projections  138 ,  140 , with doorside bracket  128  located above first projection  138  when assembled. 
     First and second projections  138 ,  140  may have holes that are vertically aligned with one another. Unlike upper attachment unit  10  that uses bearing  100  within hole  88  in doorside bracket  16 , lower attachment unit  12  may have a bearing  142  inside the hole in first projection  138  and a bearing  144  inside the hole in second projection  140 . Similar to upper attachment unit  10 , an elongated retainer  146  may be press fitted for use with lower attachment unit  12 , as best shown in  FIG. 8 . Prior to press fitting, a non-circular washer  150 , bearing  144 , bodyside bracket  130 , and bearing  142  may be placed around elongated retainer  146  and held in place by lip  148 . After press fitting, lip portion  148  and a press fitting formed spherical head  154  retain these components as a subassembly. A rotatable lower hinge  156  is thus formed in the same process by orienting bearings  142  and  144  to provide freedom between elongated retainer  146  and first and second projections  138 ,  140 . At this stage, rotatable lower hinge  156  has been assembled separate from any joints that will be disassembled at any stage of the vehicle assembly process. 
     Rotatable lower hinge  156  may now be attached to doorside bracket  128 , as shown in  FIGS. 7A ,  7 B and  8 . A chamfered portion  158  of hole  170  in doorside bracket  128  and seat  152  of elongated retainer  146  help align lower attachment unit  12  and create a snug fit, and section  160  of elongated retainer  146  fits within hole  170  to further facilitate rotation of doorside bracket  128  relative to bodyside bracket  130 . In one embodiment, chamfered portion  158  on doorside bracket  128  may be common to both upper and lower attachment units  10 ,  12 , and in another embodiment (as shown in  FIG. 8 ), chamfered portion  158  may be unique to doorside bracket  128  used with lower attachment unit  12 . Lastly, a central bolt  162  may be inserted into elongated retainer  146  to engage with internal threads  164 . Therefore, once assembled, lower attachment unit  12  may be disassembled on the vehicle assembly line without impacting rotatable lower hinge  156 , similar to disassembly of upper attachment unit  10 . Lower attachment unit  12  may include additional similar features as discussed above for upper attachment unit  10 . For example, lower attachment unit  12  may include a ribbed segment  166  as shown in  FIG. 7A  or a tapered bodyside bracket as previously discussed. 
     The initial attachment of vehicle door  38  to vehicle body member  26  will now be described in more detail with reference to  FIGS. 9-12 . 
     Once upper and lower attachment units  10 ,  12  are initially assembled, vehicle door  38  may be placed in a fixture (not shown) where units  10 ,  12  may be attached. In order to attach units  10 ,  12  to vehicle door  38 , fastener  92  on upper attachment unit  10  and a fastener  168  on lower attachment unit  12  may be driven into mating components on door  38 . In order to properly align bodyside bracket  14  along vehicle body member  26 , locating pin  40  may then be placed through locating hole  32  which may be larger than the shank diameter of locating pin  40 , thus allowing pin  40  to have some degree of translational freedom within hole  32 . Locating pin  40  may thus be fixed to bodyside bracket  14  once aligned with a precise hole in the fixture. This precise hole may receive locating pin  40 , and represent the accurate location along body member  26  on which door  38  should be attached. Next, vehicle door  38  may be attached to body member  26  by placing locating pin  40  in a corresponding hole on body member  26 . Since pin  40  may still rotate with door  38  attached, an additional reference point may be used. This additional reference may include, for example, aligning a hole on door  38  with a hole on body member  26  or aligning a door latch unit location with a striker member. Generally, door  38  can be attached to body member  26  with accuracy when the additional reference is farthest away from locating pin  40 . This may be one reason why lower attachment unit  12  need not serve as the additional reference and need not have its own locating pin. Once aligned, fasteners  34 ,  36 ,  132 , and  134 , which likewise may have some degree of translational freedom, can be driven into mating components on body member  26 . 
     Alternatively, vehicle door  38  may be aligned to vehicle body member  26  with a laser positioning system as opposed to using locating pin  40 . Like locating pin  40 , the laser system could similarly align points along door  38  with corresponding points along the periphery of the door opening. 
     In order to provide increased access for installing various internal vehicle components, door  38  may be temporarily removed from vehicle body member  26  as discussed below. This procedure may also be advantageous for a doors off subassembly of door  38 . In an effort to efficiently and expediently remove door  38  from body member  26 , central bolt  18  of upper attachment unit  10  may be removed from retainer  20  and central bolt  162  of lower attachment unit  12  may be removed from elongated retainer  146 . Bolts  18  and  162  may serve as two controlling fasteners for detaching and reattaching vehicle door  38  to body member  26 . Removing bolts  18  and  162  does not alter or disassemble rotatable upper hinge  120  and rotatable lower hinge  156 , which remain intact and unaffected by this temporary removal of door  38 . At this point, vehicle door  38  may be lifted off body member  26  as shown in  FIG. 9 . Doorside bracket  16  can remain attached to door  38  as illustrated in  FIG. 10 , and bodyside bracket  14  can remain attached to body member  26  as illustrated in  FIG. 11 . Bodyside bracket  130  of lower attachment unit  12  can similarly remain attached to body member  26  and doorside bracket  128  of lower attachment unit  12  can remain attached to door  38 . 
     In order to facilitate the aforementioned assembly and disassembly processes, upper attachment unit  10  is configured so that central bolt  18  may be removed from the bottom of unit  10 , and lower attachment unit  12  is configured so that central bolt  162  may be removed from the top of unit  12 . This configuration may be advantageous because it provides clearance for tooling on the assembly line. Since modern styling in vehicle doors typically features a rounded profile along tops and bottoms of doors, clearance for tooling can become a problem if upper attachment units are designed to be driven from the top and lower attachment units are designed to be driven from the bottom. The design of upper and lower attachment units  10  and  12  of the present invention avoids this problem. 
     When the time is appropriate for door  38  to be reattached to body member  26 , upper and lower attachment units  10 ,  12  may once again take advantage of the alignment features mentioned further above. These alignment features, such as chamfered rim  50  and seat  52  or chamfered portion  158  and seat  152 , help expedite the initial attachment and also the reattachment processes. New central bolts may replace central bolts  18  and  162 , or the original central bolts  18  and  162  may be driven back into retainer  20  and elongated retainer  146 , respectively. 
     In an alternative operation,  FIG. 12  illustrates how either central bolt  18  or fastener  92  may be temporarily removed when vehicle door  38  is removed from body member  26 . The same concept may be applied to lower attachment unit  12  as well. Such an option could also keep rotatable upper hinge  120  and rotatable lower hinge  156  intact during disassembly and reattachment of upper and lower attachment units  10  and  12 . The option of removing fastener  92  would provide an alternative path for tooling and may be helpful for compact vehicle closure members with aggressive profile curvature. 
     Those skilled in the art would appreciate in view of this disclosure that in other embodiments two upper attachment units  10  or two lower attachment units  12  may be used instead of one upper attachment unit  10  and one lower attachment unit  12 . Hence the terminology “upper” and “lower” is used throughout this description only for facilitating a better understanding of the invention. Yet further, the present invention is not limited to vehicle side doors. Upper attachment unit  10  or lower attachment unit  12  may readily be used to hingedly attach a tailgate, a trunk, a rear vehicle door etc. 
     To summarize, the invention thus provides a durable and robust door-to-body hinge system including upper and lower attachment units  10 ,  12 , the hinges of which remain intact when the door is lifted off the vehicle body for separate subassembly. The invention further provides a hinge system that uses cost effective stamped components, and minimal joints for attaching, removing, and reattaching a door to a vehicle body. 
     Although particular embodiments have been described in detail herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those particular embodiments, and that various changes and modifications may be affected therein by one skilled in the art without departing from the scope or spirit of the invention as defined in the appended claims.