Abstract:
A knuckle hub assembly ( 10 ) and a method for manufacturing same whereby brake run out is produced includes a knuckle ( 12 ), a bearing ( 28 ) press fit into the knuckle ( 12 ), and a wheel hub ( 14 ) coupled to the bearing ( 28 ) and rotateable with respect to the knuckle ( 12 ). The wheel hub ( 14 ) has a flange surface ( 34 ) having a relief channel ( 60 ) formed therein. A plurality of wheel studs ( 44 ) are press fit into bolt opening ( 42 ) formed in the relief channel ( 60 ). This arrangement provides a flat flange surface ( 34 ) for mating with a rotor ( 42 ) to minimize brake run out. The knuckle hub assembly ( 10 ) is mounted into a floating tool for finish turning of the flange surface ( 34 ) to provide minimal run out and maximum flatness.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 11/012,074, filed on Dec. 14, 2004, now abandoned which is a continuation of U.S. patent application Ser. No. 10/658,861, filed Sep. 9, 2003, now abandoned. The &#39;861 patent application is a continuation of U.S. patent application Ser. No. 10/016,589, filed Dec. 14, 2001, now U.S. Pat. No. 6,634,266, which is a continuation of U.S. patent application Ser. No. 09/414,113 filed Oct. 8, 1999, now U.S. Pat. No. 6,485,109. The &#39;113 patent application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/136,535, filed May 28, 1999. Each patent and patent application identified above is hereby incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates generally to motor vehicle wheel end components. More particularly, the present invention relates to a knuckle/hub assembly having a unique assembly and manufacturing process for reducing lateral run-out and a unique apparatus for machining the rotor-mounting flange surface of the wheel hub. 
     BACKGROUND ART 
     Most motor vehicles today include disc brake systems for the front axle wheel assemblies and many further include disc brakes at the rear axle position. The disc brake rotor is a circular metal disc having opposed braking surfaces that are clamped by brake pads carried by a brake caliper to exert a braking effect. The wheel hub typically incorporates an anti-friction wheel bearing assembly in which one race of the bearing is coupled to the vehicle suspension and the other rotationally mounts the wheel hub, the brake rotor and wheel. Ordinarily, the rotating components of the rotor and hub assembly are manufactured separately and assembled together. This enables the brake rotor to be serviced and replaced if necessary during use. Moreover, the desired material characteristics for a brake rotor and the hub components are different. Although efforts to integrate these components have been proposed, such an approach has not found widespread acceptance. 
     In order to enhance performance of the braking system, it is desired to carefully and accurately control the dimensional characteristics of the rotor braking surfaces as the rotor rotates. The thickness variation of the disc and the lateral run-out or lateral deflection of the surfaces as they rotate need to be held to minimum tolerances. Similarly, the radial run-out of the outer edges of the braking surfaces need to be controlled to ensure that the brake pads engage as much of the available rotor braking surface as possible without overlapping the edges of the rotor which gives rise to brake run-out. However, manufacturers have faced difficulties in achieving enhanced control over these tolerances due to the influence of several factors. 
     Most efforts to date have focused on decreasing run-out by controlling the dimensional characteristics of the rotor, and, therefore, the relationship of the rotor surface to the wheel hub flange or surface. However, despite the fact that the tolerances and dimensional characteristics of the rotors have improved, performance and run-out problems still exist. These run-out problems are due, in large part, to other components of the wheel end assembly, including the bearing/hub assembly, which is comprised of a wheel hub and a bearing or the knuckle/hub assembly, which is comprised of a knuckle, a heel hub, and a bearing. 
     One factor that contributes to this run-out is the stack-up of the individual components in a knuckle/hub assembly, i.e., their combined tolerances. While the tolerances of each part can be reduced when they are separately machined, when the parts are assembled, the combined tolerances stack up, causing run-out that is still relatively significant. Another factor that contributes to stack-up is any variation in the turning processes that are used to machine the flange surface, when the wheel hub is individually machined, in an effort to make it flat with respect to the rotor. Further, the installation and press condition of the wheel bolts, the assembly process of the knuckle/hub assembly, and improperly pre-loaded bearings, can all cause misalignment of the hub surface with respect to the rotor and thus cause unacceptable run-out. This run-out can cause premature failure of the brake lining due to uneven wear which requires premature replacement of the brake lining at an increased expense. Further, problems due to run-out include, brake judder, steering wheel “nibble” and pedal pulses felt by the user, and warped rotors which result in brake noise and uneven stopping. 
     Presently available manufacturing methods and designs of knuckle hub assemblies limit the accuracy to which lateral run-out of braking surfaces can be controlled. These methods and designs are also insufficient to solve the problems associated with run-out, as discussed above. Current methods typically involve finishing the knuckle and the hub individually and then assembling the machined parts to form a completed knuckle/hub assembly. These methods, however, do not solve the run-out problems due to the factors discussed above, including stack-up tolerances, turning process variations, and wheel bolt and bearing installations. 
     Other options have been considered in an effort to solve the run-out problem, but they also all suffer from a variety of disadvantages. One contemplated option for reducing run-out is to separately decrease the run-out of each individual component, by decreasing their respective tolerances during manufacture and then assembling the components. The “stack up” of tolerance variations related to such an approach is still significant and provides only limited system improvement at an increased manufacturing cost. Another contemplated option includes tightening the press-fit tolerance variation between the knuckle, the wheel hub, and the bearing. This, however, significantly increases the difficulty in the assembly process as well as increases the manufacturing cost. Further, this option does not provide the desired reduction in system run-out. 
     It would therefore be advantageous to design a knuckle/hub assembly for a motor vehicle that decreases system run-out without significantly increasing the manufacturing cost of the assembly or increasing the manufacturing difficulty. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a knuckle/hub assembly and a method for manufacturing same that provides reduced wheel hub lateral run-out. 
     It is a further object of the present invention to provide a knuckle/hub assembly and method for manufacturing same that results in a brake configuration which minimizes brake noise and uneven stopping. 
     It is still a further object of the present invention to provide a knuckle/hub assembly and method for manufacturing same that results in a brake configuration which minimizes uneven brake lining wear and thus the need for frequent lining replacements. 
     It is a related object of the present invention to provide a knuckle/hub assembly and a method for manufacturing same that results in a brake configuration which increases the life of vehicle brake linings. 
     It is yet another object of the present invention to provide a knuckle/hub assembly and a method for manufacturing same that results in a brake configuration which provides improved performance at relatively lower cost. 
     It is yet a further object of the present invention to provide a tool to allow for the machining of a knuckle/hub assembly to provide decreased lateral run-out on the outboard wheel hub flange face. 
     In accordance with the objects of the present invention a knuckle/hub assembly for a motor vehicle is provided. The knuckle/hub assembly includes a knuckle having a plurality of apertures formed therein for attachment of the knuckle to a vehicle. The knuckle also includes a bearing retention portion. The knuckle bearing retention portion is in communication with a bearing through press-fitting. The bearing in turn is in rotational communication with a wheel hub. The wheel hub includes a neck portion that is pressed into the bearing, and a flange. The flange has a flange face, which includes an outer portion, an inner portion, and a relief channel that is formed in the flange face between the outer portion and the inner portion. The relief channel has a plurality of bolt holes formed therein with each of the plurality of bolt holes receiving a wheel bolt passed therethrough. The inner portion and the outer portion are disposed on the same plane and are parallel to the caliper mounting features, and wherein the inner and outer portions have minimal run out with respect to the bearing axis of rotation. 
     In accordance with another object of the present invention, a method for forming a knuckle/hub assembly having reduced run-out is provided. The method includes providing a knuckle having a generally circular bore formed therein. The generally circular knuckle bore has a bearing press-fit therein. A wheel hub having a neck portion and a flange portion with a flange face is provided. The flange face is then machined to form a relief channel therein, which divides the flange surface into an inner portion and an outer portion. The inner portion and the outer portion of the wheel hub flange face are each finished. The relief channel has a plurality of wheel bolts press-fit into bolt holes formed therein. The neck portion of the wheel hub is then journaled into the bearing such that the wheel hub can rotate with respect to the knuckle. The knuckle/hub assembly is then mounted such that the flange face is then final finished with the inner portion and the outer portion being co-planar and parallel with respect to the caliper ears. 
     In accordance with another object of the present invention, an assembly for  holding a knuckle/hub assembly while it is final finished is provided. The assembly includes a standard lathe machine with a fixture for clamping and locating the knuckle/hub assembly. The fixture applies a clamping force to the wheel hub and the inner race of the bearing to generate a pre-load on the bearing. The fixture also holds the knuckle in place so that the wheel hub may be rotated. Thereafter, the inner and outer surfaces of the flange face are final finished so that they are flat and co-planar with respect to each other. These two surfaces have minimal run-out when measured back to the knuckle/hub assembly&#39;s axis of rotation. 
     These and other features and advantages of the present invention will become apparent from the following description of the invention when viewed in accordance with the accompanying drawings and appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a knucklehub assembly in accordance with a preferred embodiment of the present invention; 
         FIG. 2  is an exploded cross-sectional view illustrating the components of a knuckle/hub assembly and a brake rotor in accordance with a preferred embodiment of the present invention; 
         FIG. 3  is a cross-sectional view of the knuckle/hub assembly in accordance with a preferred embodiment of the present invention; 
         FIG. 4  is a rear view of a knuckle/hub assembly in accordance with a preferred embodiment of the present invention; 
         FIG. 5  is an end view of a wheel hub flange face in accordance with a preferred embodiment of the present invention; 
         FIG. 6  is a cross-sectional view of the wheel hub of  FIG. 5  along the  6 - 6 ; 
         FIG. 7  is a top view of a manufacturing fixture assembly for use in the generation of a knuckle/hub assembly in accordance with a preferred embodiment of the present invention; 
         FIG. 8  is a bottom view of a manufacturing fixture assembly with a knuckle/hub assembly clamped therein in the direction of the arrow  8  in  FIG. 9  in accordance with a preferred embodiment of the present invention; 
         FIG. 9  is a cross-sectional view of the manufacturing fixture assembly and knuckle/hub assembly clamped therein of  FIG. 7  in the direction of the arrows  9 - 9 ; 
         FIG. 10  is a cross-sectional view of a puller member of the manufacturing fixture assembly of  FIG. 7  in the direction arrows  10 - 10 ; 
         FIG. 11  is a cross-sectional view of the manufacturing fixture assembly, with a knuckle/hub assembly positioned therein, of  FIG. 9  in the direction of the arrows  11 - 11 ; 
         FIG. 12  is a cross-sectional view of the manufacturing fixture assembly, with a knuckle/hub assembly positional therein, of  FIG. 9  in the direction of the arrows  12 - 12 ; 
         FIG. 13  is a cross-sectional view of an alternative embodiment of a wheel hub assembly in accordance with a preferred embodiment of the present invention; 
       and  FIG. 14  is a cross-sectional view of another alternative embodiment of a wheel hub assembly in accordance with a preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1 through 4  illustrate a preferred knucklehub assembly, as generally indicated by reference number  10 , in accordance with the present invention. The assembly  10  is comprised of a variety of components, including a knuckle  12  and a wheel hub  14 . The knuckle  12  is preferably constructed of metal and is generally formed by casting while the wheel hub  14  is preferably constructed of metal. The knuckle and hub can obviously be formed of other materials. The knuckle  12  preferably has a generally circular bore  16  formed therein and a plurality of outwardly extending appendages  18  that attach to the vehicle through a plurality of apertures  20  formed in the plurality of legs  18 , as is well known in the art. 
     The bore  16  has a recess  22  formed therein bounded by an upper snap ring groove  24  and a lower snap ring  26  or shoulder for receiving a bearing  28  press fit therein. A snap ring  29  is preferably press fit or otherwise secured into the upper snap ring groove  24  prior to engagement of the bearing  28  with the knuckle  12 . It should be understood that while the illustrated assembly has a bore  16  formed in the knuckle  12 , the bearing  28  can be attached or secured to the knuckle  12  in a variety of configurations. For example, the bearing  28  can be mounted to an upper surface or other portion of the knuckle  12 . Alternatively, the bearing  28  can be only partially disposed in the bore  16 . Additionally, the bore  18  can be eliminated altogether. 
     The bearing  28  preferably has an outer race  31  and an inner race  33 . However, it should be understood that a variety of different beatings may be utilized as well as a variety of different knuckle/bearing attachment configurations. For example, instead of being press-fit with a snap ring, i.e., between the upper retention ring  24  and the lower retention ring  26 , the bearing  28  may be press-fit without a snap ring and held in place with a nut or other known securing methods. Alternatively, the outer race  31  may be integrally formed with the knuckle  12  ( FIG. 14 ) or may be configured as an orbital formed outer race rotation bearing/knuckle assembly. Further, the bearing outer race  31  could alternatively be bolted to the knuckle  12  such that the inner race  33  rotates with the wheel hub  14 . Moreover, the inner race  33  may be integrally formed with the wheel hub  14  ( FIG. 13 ). Further, a spindle configuration having a non-driven outer race rotation may also be utilized. 
     In the preferred embodiment, the wheel hub  14  has a neck portion  30  and a flange portion  32 . The neck portion  30  is preferably pressed into contact with the inner race  33  of the bearing  28  so that the wheel hub  14  can rotate with respect to the knuckle  12 , as shown in  FIG. 3 . Alternatively, the neck portion  30  may be integrally formed with the inner race  33  or the outer race  31 . It should be understood that other wheel hub/bearing configurations may also be utilized. 
     The flange portion  32  has a flange face  34  and a wheel and rotor pilot portion  36 . The wheel and rotor pilot portions  36  extend generally upwardly from the flange face  34  and has an inner surface  38 , which defines a spline  40 . The wheel hub  14  also has a plurality of bolt holes  42  formed in the flange face  34  through which a plurality of respective wheel bolts  44  are passed. The plurality of wheel bolts  44  are attached to the flange face  34  in a predetermined pattern and on the same pitch circle diameter. The wheel bolts  44  are oriented with the threaded ends extending outwardly so as to connect a rotor  46  and associated wheel onto the hub  14  in a fashion, which is more clearly described below. Alternatively, the wheel hub  14  may have bolt holes  42  that receive lug nuts that are attached to a vehicle wheel and are passed through the bolt holes  42  when the wheel is attached to the wheel hub  14 . 
     As best shown in  FIG. 2 , the rotor  46  comprises a cup  48  with a central aperture  50  adapted to receive therethrough a wheel shaft (not shown) affixed to the wheel and rotor pilot portions  36  and extending outwardly from the flange face  34 . The cup  48  is dimensioned to receive the hub flange portion  32  and includes at its outer end an annular flange  52  having a plurality of apertures  54  lying in the same pitch circle diameter relative to the wheel shaft as the wheel bolts  44  and having a similar pattern so as to accommodate the wheel bolts  44  therethrough. 
     A pair of parallel, annular discs  56  spaced from each other by a plurality of rectangular fillets  58  extend outwardly from the cup  48  and define braking surfaces for a plurality of brake calipers (not shown). The completion of the assembly to the wheel is done by positioning the wheel over the bolts  44  and the threading nuts (not shown) over the bolts  44  so as to secure the wheel between the nuts and the rotor  46 . This invention addresses, among other things, the problems, which occur between the mating surfaces of the hub flange portion  32  and the rotor  46 . 
     Turning now to  FIGS. 5 and 6 , which illustrate the preferred wheel hub  14  and flange portion  32  of the present invention. The flange face  34  has a relief channel  60  machined therein. It should be understood that the relief channel  60  may also be forged into the flange face  34  or may be formed by other known methods. The relief channel  60  divides the flange face  34  into an outer flange surface  62  and an inner flange surface  64 . The relief channel  60  is turned into the flange face  34  so that the plurality of bolt holes  42  lie in the relief channel  60 . The plurality of bolt holes  42  may be formed either before or after the relief channel  60  has been formed. The relief channel is preferably set below the level of the flange face  34 , this is to eliminate any surface unevenness caused by press-fitting the wheel bolts  44  into the bolt holes  42 . Any unevenness due to press-fitting of the wheel bolts  44  is compensated for by the relief channel  60  as any unevenness will not be raised with respect to the flange  62 ,  64 , and therefore does not contribute to any run-out. The relief channel  60  also allows for final finishing or finish turning to be performed on the assembly  10  after the bolts  44  have been seemed to the wheel hub  14 . 
     The relief channel  60  is preferably formed in the flange surface  34  prior to the knuckle  12 , the bearing  28 , and the wheel hub  14  being assembled. However, it should be understood that the relief channel  60  can be formed in the flange surface  34  after the wheel hub  14  is assembled to the bearing  28  and the knuckle  12  and before the wheel studs  44  are press-fit therein. In accordance with the preferred method of forming, the wheel hub  14  has the relief channel  60  formed therein. Thereafter, the outer flange surface  62  and the inner flange surface  64  are finished. After the finishing process has been completed, the wheel bolts  44  are press fit into the bolt holes  42 . Thereafter, the hub  14  is mounted to the bearing  28  and the knuckle  12  to form the completed knuckle/hub assembly  10 . 
     The assembly  10  is then placed into a clamping apparatus, as is discussed in more detail below, where it is finish turned or final finished to provide a flat outer flange surface  62  and a flat inner flange surface  64  that will contact the rotor  46  and thus, minimize any run out. The refinishing will provide an inner flange surface  64  and an outer flange surface  62  that are co-planar with respect to each other so as to provide a flat flange surface  34 . The re-finishing process minimizes run-out with respect to not only the rotor, but also to the center of rotation of the assembly  68 , as established by the bearing  28 . Further, the method and configuration of the present invention allows the distance between the caliper ears and the flange surfaces  62 ,  64  to be accurately controlled. Additionally, the parallelism between the caliper ears and the flange surfaces  62 ,  64  can also be accurately controlled. In the preferred embodiment, each flange surface has a flatness of 20 micrometers (or microns) or better. Additionally, the run-out is minimized to 14 micrometers (or microns) or better and the co-planarness of the inner and outer surfaces  62 ,  64  is 20 micrometers or better. However, the flatness requirements may be varied. A person having ordinary skill in the art will appreciate that as used herein the terms “or better” mean less than or having a flatness better than the mentioned amount. For example, a flatness of 15 microns is a flatness better than 20 microns. 
       FIGS. 7 through 12  illustrate a preferred part clamping fixture  70  in accordance with the present invention. The part clamping fixture  70  is preferably incorporated into a lathe machine (not shown) and is used to locate and hold the knuckle/hub assembly  10  for refinishing, in accordance with the process described above. 
     As shown in  FIG. 7 , the part clamping fixture  70  includes a generally flat top surface  72  for abutting a portion or surface of the lathe machine. The generally flat top surface  72  includes an opening  74  formed therein in which a split collar  76  is generally positioned for engagement with a drive motor from the lathe. The split collar  76  is disposed such that it is rotatable with respect to the opening  74 . The split collar  76  has a top surface  78  with a plurality of drive motor engagement notches  80  that communicate with the drive motor from the lathe in order to rotate the split collar  76 . 
     With reference to  FIGS. 7 through 12 , the part clamping fixture  70  is shown in more detail. The fixture  70  includes a plurality of keys  82  that fit into recesses  84  formed in the generally flat top surface  72 . The keys  82  have fasteners  86  that pass through both the keys  82  and the generally flat top surface  72  to secure the keys  82  to a spacer plate  88 . The spacer plate  88  is disposed on top of a base plate  90  with the two plates  88 ,  90  being secured by standard fasteners  92  that extend through the generally flat top surface  72 . 
     The split collar  76  has a bore  94  formed therein in which a toothed gear  96  is disposed. The toothed gear  96  is secured to a puller member  98  that, when lowered by the lathe, extends generally downward and into communication with the knuckle  12 . The toothed gear  96  is rotatable with respect to the split collar  76  and is supported at a bottom surface  100  by a u-joint adapter  102  that has a central opening  104  formed therein that encompasses the puller member  98 . 
     The part clamping fixture  70  has a right housing portion  106 , a right cover portion  108 , and a right pull piston  110  disposed in the right housing portion  106 . The part clamping fixture  70  also includes a left housing portion  114 , a left cover  116 , and a left pull piston  118  disposed within the left housing portion  114 . Both the right pull piston  110  and the left pull piston  118  are secured to the base plate  90  by respective fasteners  112 ,  120 . Each of the right housing portion  106  and the left housing portion  114  are moveable with respect to the respective pull pistons  110 ,  118  such that respective chambers  122 ,  124  are formed between each housing portion  106 ,  114 . Each chamber  122 ,  124  has an orifice  126 ,  128  in fluid communication therewith allowing fluid to enter and exit the respective chamber  122 ,  124  to assist in moving the right and left housing portions  106 ,  114  upwardly and downwardly. The left and right chambers  122 ,  124  are sealed from their respective housings  106 ,  114  by a plurality of o-rings  130 . obviously any other sealing mechanism may alternatively be utilized. The left pull piston  118  is preferably smaller in length and diameter than the right pull piston  110  to ensure that equal forces are applied to the knuckle  12 . It should be understood that the size of the pull pistons  110  and  118  may vary depending upon the knuckle configuration. 
     As shown in  FIG. 9 , a bayonet  132  is preferably inserted into the spline  40  defined by the inner surface  38  of the wheel pilot portion  36  of the flange portion  32 . The bayonet  132  is for engagement with the puller member  98  to lift the knuckle/hub assembly  10 , as described in more detail below. The bayonet  132  preferably engages a washer bore or face  133  in order to lift the assembly  10 . 
     As shown in  FIG. 11 , the right housing portion  106  is retained in proximity with the base plate  90  by a pair of retaining blocks  134 . Each of the retaining blocks  134  has a supporting portion  136  that engages a flange portion  138  of the right housing portion  106 . Each of the retaining blocks  134  is secured to the base plate  90  by a fastener  140  or the like. A pair of guide pins  142  are disposed in the right housing portion  106 . Each of the guide pins  142  is secured to the base plate  90  at an upper end  144  and each is in communication with a spring  146  at a lower end  148 . Each spring  146  fits within a recess  150  formed in the lower end  144  of each of the guide pins  142  and extends downwardly into contact with the right housing portion  106 . The biasing force from the springs  146  helps bias the right housing portion  106  away from the guide pins  142 . 
     As also shown in  FIG. 11 , the right housing portion  106  includes a pair of bores  152  within which a respective piston  154  reciprocates. Each piston  154  moves between a normally unengaged position and a knuckle engaging position. The bores  152  are each sealed adjacent the outer ends  156  of the pistons  154  by an end cap  158 . The inner ends  160  of each of the pistons  154  has a gripper portion  162  and a swiveling gripper portion  164  which allow the piston  154  to engage and hold the upper strut arm  155  of the knuckle  12  when the piston  154  is in the knuckle engaging position. Each piston  154  reciprocates within a bushing  166  secured within the respective bore  152  to ensure proper alignment of the gripper portions  162  and the swiveling gripper portions  164  with respect to the upper strut arm  155 . 
     Turning now to  FIG. 12 , which is a cross-sectional view of the fixture assembly  70  through the left housing portion  114 . The left housing portion  114  is also retained in proximity with the base plate  90  by a pair of retaining blocks  168 . Each of the retaining blocks  168  has a supporting portion  170  that engages a flange portion  171  of the left housing portion  114 . Each of the retaining blocks  168  is secured to the base plate  90  by a fastener  172  or other securing means. A pair of guide pins  174  are disposed in the left housing portion  114 . Each of the guide pins  174  is secured to the base plate  90  at an upper end  176  and each is in communication with a spring  178  at a lower end  180  of the guide pins  174 . Each spring  178  fits within a recess  182  formed in the lower end  180  and extends downwardly into contact with the left housing portion  114 . The biasing force from the springs  178  helps bias the left housing portion  114  away from the guide pins  174 . The left guide pins  174  are preferably smaller in length and diameter than the right guide pins  142 . 
     As also shown in  FIG. 12 , the left housing portion  114  includes a pair of bores  184  within which a respective piston  186  reciprocates. Each piston  186  moves between a normally unengaged position and a knuckle engaging position. The bores  184  are each sealed adjacent the outer ends  188  of the pistons  186  by a respective end cap  190 . The inner ends  182  of each of the pistons  186  have a gripper portion  194  and a swiveling gripper portion  196  which allow the pistons  186  to engage and clamp the lower ball joint  198  of the knuckle  12  when the pistons  186  are in a knuckle engaging position. Each piston  186  reciprocates within a busing  188  secured within each bore  184  to ensure proper alignment of the gripper portion  194  and the swiveling gripper portion  196  with respect to the lower ball joint  198 . 
     Referring now to  FIGS. 9 and 10 , which illustrate the puller member  98  and the surrounding encasing  200 . The puller member  98  has a head portion  202  around which the toothed gear  96  is located, a neck portion  204  which passes through the opening  104  in the u-joint adapter  102 , and a stem portion  206  which is rotatable within a bore  208  formed in the surrounding encasing  200 . The surrounding encasing  200  has a plurality of bearings  210  disposed around the bore  208  to assist in the rotation of the stem portion  206 . 
     The encasing  200  includes an upper body portion  212  that has an upper end cap portion  214  disposed thereabove, a lower end cap portion  216  disposed therebelow, and a spacer portion  218  disposed between the upper body portion  212  and the lower end cap portion  216 . The components of the upper body portion  212  are held together by a fastener  220  or other securing mechanism. The encasing  200  also includes a lower stop portion  222  which is secured to an upper end cap  224  by a fastener  226  or other securing mechanism. The upper body portion  212  and the lower stop portion  222  are surrounded by a body portion  228  having a stop portion  230  secured thereto. The encasing  200  is preferably secured to the underside of the base plate  90  by a plurality of fasteners  232 , such as bolts or other securing mechanisms. 
     An upper reservoir  234  is preferably formed in the upper body portion  212 . The upper reservoir  234  is in fluid communication with a fluid inlet port  236  for receiving hydraulic fluid therein. The upper reservoir  234  is also in fluid communication with a first fluid orifice  238  formed in the stem portion  206  of the puller member  98 . The first fluid orifice  238  is in fluid communication with an internal fluid passageway  240  which is in fluid communication with a second fluid orifice  242  formed in the stem portion  206 . Fluid that passes through the second fluid orifice  242  is passed into a lower reservoir  244 . The lower reservoir  244  is formed between the lower stop portion  222  and the upper end cap  224 . 
     The stem portion  206  has an annular flange  246  integrally formed thereon. The annular flange  246  is preferably disposed in the lower reservoir  244 . The annular flange  246  and the upper end cap  224  are in mechanical communication through the inclusion of a plurality of springs  248  disposed in recesses  250 ,  252  formed in their respective surfaces and a spring drive pin  254 . Thus, as hydraulic fluid enters the lower reservoir  244  through the second fluid orifice  242 , the annular flange  246  is caused to move upward against the force of the springs  248 . 
     In operation, a knuckle/hub assembly  10  which is to be refinished in accordance with the process, as described in detail above, is located in the lathe and generally beneath the part clamping fixture  70 . The knuckle/hub assembly  10  is preferably resting on a pallet or other supporting structure with unobstructed passages. After the knuckle/hub assembly  10  has been located on the pallet beneath the part clamping fixture  70 , the bayonet  132  enters the spline  40  of the assembly  10  by passing up through the pallet upon which the assembly  10  is resting. The bayonet  132  is pressed upward until a shoulder portion  256  contacts the washer face  133  of the flange portion  32  forcing it upward. The assembly  10  is lifted by the bayonet  132  at least enough so that the wheel studs  44  are clear from the pallet  10 . 
     Thereafter, the lathe lowers the puller member  98  and the puller encasing  200  through the opening  74  and into communication with the knuckle  12 . The stem portion  206  of the puller member  98  has a recess  258  formed at its lower end  260  which is opposite the head portion  202 . The recess  258  is non-uniform in diameter as in one orientation, it is large enough to receive a rounded top portion  260  of the bayonet  132  therewithin. However, when the stem portion  206  is rotated 90 degrees, its diameter is not large enough to receive the rounded top portion  260  therewithin or to allow the rounded top portion  260  to be withdrawn from the recess  258  if it is positioned therein. Thus, when the puller member  98  is lowered, it is oriented so as to receive the rounded top portion  260  therewithin. 
     After the puller member  98  and the puller encasing  200  have been lowered, the pair of right pistons  154  and the pair of left pistons  186  are hydraulically actuated in order to apply a pinching or clamping force to the knuckle  12 . The right pistons  156  apply a clamping force to the opposing sides of the upper strut arm  155  through the use of the gripper portions  162  and the swiveling gripper portions  164 . Similarly, the left pistons  186  apply a clamping force to the opposing sides of the lower ball joint  198  through the use of the gripper portions  192  and the swiveling gripper portions  196 . The lifting of the assembly  10  by the bayonet  132  and the lowering of the puller member  98  forces the knuckle  12  into contact with the stop portion  230 . The stop portion  230  has an annular shoulder  262  which engages knuckle  12 . These actions locate the knuckle/hub assembly  10  within the lathe and also fix the knuckle  12  to the lathe separately from any drive mechanism. Further, the knuckle  12  acted on by the pullers and grippers so that the knuckle is fixed and located. The knuckle  12  is not exposed to any bearing pre-load force. 
     After the assembly  10  is located, the bayonet  132  is engaged by rotating the puller member  98  and the puller encasing  200  with respect to the surrounding body portion  228 . The puller member  98  and the puller encasing  200  are free to rotate with respect to the body portion  228  and are rotated 90.degree. in order to engage the bayonet  132 . Thereafter, a clamping force is introduced by applying pressure to the annular flange  236  by introducing hydraulic fluid into the lower reservoir  244  through the second fluid orifice  242  forcing the puller  20  upward. By pulling the puller member  98  up, the bayonet  132  is also pulled upward such that the lower stop portion  222  sits on the inner race  31  of the bearing  28  in order to apply a force thereto and thus preload the bearing  28 . 
     After the assembly  10  has been located and clamped as described above, the final finishing process of the inner and outer surfaces  62 ,  64  of the hub flange face  34  can be performed by a finishing tool. In such a process, the hub  14  is driven such that it is rotating with respect to the knuckle  12  in which is fixed. The finishing tool is also preferably single tool such as a CNC tool, as is well known in the art. However, a variety of the other finishing tools may alternatively be utilized. 
     One of the features of the fixture assembly  70  is to turn the wheel hub  14  and the bearing  28  compliantly, such that the stem portion  206  and the annular flange  246  are free to float and follow the knuckle/hub bearing&#39;s axis of rotation. It is further preferred that the flange surface  34  is probed before final finishing to ensure a small final finish cut, i.e., decreasing the amount of material removal that is required during the final finish cut. This helps control the distance between the caliper ears and the flange face  34 . 
     Other objects and features of the present invention will become apparent when reviewed in light of detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.