Abstract:
The invention relates to a composite brake caliper and method for producing the same. The method for producing the composite brake caliper comprises the steps of: (a) providing a molding apparatus having at least a pair of mold sections, at least one of the pair of mold sections including at least one projection extending from a surface thereof; (b) providing at least one reinforced preform formed from at least a first material, the preform having at least one opening formed at least partially therein; (d) positioning the preform in the molding apparatus with the projection of the mold section extending into the opening of the preform so as to orient the preform in a predetermined position within the molding apparatus; and (e) casting a caliper body formed from a second material in situ therewith to produce the composite brake caliper.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates in general to vehicle disc brake assemblies and in particular to an improved structure for a composite caliper adapted for use in such a vehicle disc brake assembly and method for producing such a brake caliper. 
     Most vehicles are equipped with a brake system for slowing or stopping movement of the vehicle in a controlled manner. A typical brake system for an automobile or light truck includes a disc brake assembly for each of the front wheels and either a drum brake assembly or a disc brake assembly for each of the rear wheels. The brake assemblies are actuated by hydraulic or pneumatic pressure generated when an operator of the vehicle depresses a brake pedal. The structures of these drum brake assemblies and disc brake assemblies, as well as the actuators therefor, are well known in the art. 
     A typical disc brake assembly includes a rotor which is secured to the wheel of the vehicle for rotation therewith. The rotor includes a pair of opposed friction plates which are selectively engaged by portions of a caliper assembly. The caliper assembly is slidably supported by pins secured to an anchor plate. The anchor plate is secured to a non-rotatable component of the vehicle, such as the vehicle frame. The caliper assembly includes a pair of brake shoes which are disposed on opposite sides of the rotor. The brake shoes are operatively connected to one or more hydraulically actuated pistons for movement between a non-braking position, wherein they are spaced apart from the opposed friction plates of the rotor, and a braking position, wherein they are moved into frictional engagement with the opposed friction plates of the rotor. When the operator of the vehicle depresses the brake pedal, the piston urges the brake shoes from the non-braking position to the braking position so as to frictionally engage the friction plates of the rotor and thereby slow or stop the rotation of the associated wheel of the vehicle. 
     In order to reduce the weight of the disc brake assembly, it is known to reduce the weight of the caliper assembly of the disc brake assembly. Specifically, it is known to reduce the weight of an associated caliper of the caliper assembly. However, during braking, the caliper must be sufficiently stiff to withstand the braking forces which are generated. Thus, it would be desirable to provide a reduced weight caliper structure which was simple and economical, yet sufficiently stiff to withstand braking forces. 
     SUMMARY OF THE INVENTION 
     This invention relates to an improved structure for a composite brake caliper adapted for use in a vehicle disc brake assembly and method for producing such a composite brake caliper. The method for producing the composite brake caliper comprises the steps of: (a) providing a molding apparatus having at least a pair of mold sections, at least one of the pair of mold sections including at least one projection extending from a surface thereof; (b) providing at least one reinforced preform formed from at least a first material, the preform having at least one opening formed at least partially therein; (d) positioning the preform in the molding apparatus with the projection of the mold section extending into the opening of the preform so as to orient the preform in a predetermined position within the molding apparatus; and (e) casting a caliper body formed from a second material in situ therewith to produce the composite brake caliper. 
    
    
     Other advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiments, when read in light of the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a portion of a prior art vehicle disc brake assembly. 
     FIG. 2 is an exploded perspective view of a portion of the prior art disc brake assembly illustrated in FIG.  1 . 
     FIG. 3 is a sectional elevational view of a portion of the prior art disc brake assembly illustrated in FIG.  1 . 
     FIG. 4 is a top view of a first embodiment of an improved structure for a caliper in accordance with this invention. 
     FIG. 5 is a side view of the caliper illustrated in FIG.  4 . 
     FIG. 6 is a top view of a second embodiment of an improved structure for a caliper in accordance with this invention. 
     FIG. 7 is a side view of the caliper illustrated in FIG.  6 . 
     FIG. 8 is a top view of a third embodiment of an improved structure for a caliper in accordance with this invention. 
     FIG. 9 is a side view of the caliper illustrated in FIG.  8 . 
     FIG. 10 is a top view of a fourth embodiment of an improved structure for a caliper in accordance with this invention. 
     FIG. 11 is a side view of the caliper illustrated in FIG.  10 . 
     FIG. 12 is a top view of a fifth embodiment of an improved structure for a caliper in accordance with this invention. 
     FIG. 13 is a side view of the caliper illustrated in FIG.  12 . 
     FIG. 14 is a top view of a sixth embodiment of an improved structure for a caliper in accordance with this invention. 
     FIG. 15 is a side view of the caliper illustrated in FIG.  14 . 
     FIG. 16 is a top view of a seventh embodiment of an improved structure for a caliper in accordance with this invention. 
     FIG. 17 is a side view of the caliper illustrated in FIG.  16 . 
     FIG. 18 is a top view of an eighth embodiment of an improved structure for a caliper in accordance with this invention. 
     FIG. 19 is a side view of the caliper illustrated in FIG.  18 . 
     FIG. 20 is a top view of a ninth embodiment of an improved structure for a caliper in accordance with this invention. 
     FIG. 21 is a side view of the caliper illustrated in FIG.  20 . 
     FIG. 22 is a sectional view of a portion of a mold apparatus used to produce the caliper shown in FIGS. 20 and 21 
     FIG. 23 is a side view of a portion of a tenth embodiment of an improved structure for a caliper in accordance with this invention. 
     FIG. 24 is a side view of an eleventh embodiment of an improved structure for a caliper in accordance with this invention. 
     FIG. 25 is a side view of a twelfth embodiment of an improved structure for a caliper in accordance with this invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, there is illustrated in FIGS. 1 through 3 a portion of a prior art vehicle disc brake assembly, indicated generally at  10 . The general structure and operation of the prior art disc brake assembly  10  is conventional in the art. Thus, only those portions of the prior art disc brake assembly  10  which are necessary for a full understanding of this invention will be explained and illustrated. It should be noted that while the invention is described for use with the particular prior art disc brake structure shown in the drawings, the invention can be used with other kinds of disc brake assembly structures. 
     The illustrated prior art disc brake assembly  10  includes a generally C-shaped caliper, indicated generally at  12 . The caliper  12  includes an outboard leg portion  14  and inboard leg portion  16  which are interconnected by an intermediate bridge portion  18 . The caliper  12  is slidably supported on a pair of pins  20  secured to an anchor plate, indicated generally at  22 . The pins  20  extend through respective non-threaded apertures  16 A formed through the inboard leg  16  of the caliper  12 . The pins  20  have threaded ends  20 A which are received in respective threaded apertures  22 A (only one of such threaded apertures  22 A shown in FIG.  1 ), formed through the anchor plate  22 . The pins  20  permit the caliper  12  to slide in both the outboard direction (toward the left when viewing FIG. 3) and the inboard direction (toward the right when viewing FIG.  3 ). Such sliding movement of the caliper  12  occurs when the prior art disc brake assembly  10  is actuated, as will be explained below. 
     A pair of bolts (not shown) having threaded ends extend through associated non-threaded holes formed in a stationary component of the vehicle, such as the steering knuckle (not shown) in a front wheel drive vehicle, and are received in threaded apertures  22 B (only one of such apertures  22 B shown in FIG.  2 ), formed through the anchor plate  22  to secure the anchor plate  22  to a stationary vehicle component. In the illustrated prior art disk brake assembly  10 , the caliper  12  further includes a pair of lift stops or arms  12 A and  12 B provided on a side  18 A of the bridge portion  18 , best shown in FIG. 2, and a single lift stop or arm (not shown) provided on an opposite side  18 B thereof. 
     As best shown in FIG. 2, the illustrated anchor plate  22  includes a pair of outwardly extending arms  24  which are interconnected at inner ends thereof by an inner tie bar  26  and at outer ends thereof by an outer tie bar  28 . Each of the arms  24  includes an upstanding guide rails  24 A formed thereon. The guide rails  24 A extend transverse to the arms  24  and parallel to one another. The guide rails  24 A are provided to slidably support an inboard brake shoe, indicated generally at  30 , and an outboard brake shoe, indicated generally at  40 , respectively. 
     The inboard brake shoe  30  includes a backing plate  32  and a friction pad  34 . The opposed ends of the inboard backing plate  32  have notches  32 A and  32 B formed therein for supporting the inboard brake shoe  30  on the guide rails  24 A of the anchor plate  22 . The outboard brake shoe  40  includes a backing plate  42  and a friction pad  44 . The opposed ends of the outboard backing plate  42  have notches  42 A and  42 B formed therein for supporting the outboard brake shoe  40  on the guide rails  24 A of the anchor plate  22 . 
     A pair of clip or springs  36  and  38  are disposed on a respective one of the guide rails  24 A. The clip  36  includes a pair of outer spring arms  36 A which engage and bias the associated ends of the brake shoes  30  and  40  against the anchor plate  22 , and a center spring arm  36 B which engages and biases the single lift stop of the caliper  12  downwardly against the anchor plate  22 . The clip  38  indicates a spring arm  38 A which engages both the associated ends of the brake shoes  30  and  40  and the lift stop  12 A and  12 B of the caliper  12  downwardly against the anchor plate  22 . Alternatively, as is known in the art, the inboard brake shoe  30  can be supported on a brake piston of the disc brake assembly  10 , while the outboard brake shoe  40  can be supported on the outboard leg portion  14  of the caliper  12 . 
     An actuation means, indicated generally at  50  in FIG. 3, is provided for effecting the operation of the disc brake assembly  10 . The illustrated actuation means  50  includes a pair of brake pistons  52  (only one of the pistons  52  shown in FIG.  3 ), which are slidably disposed in a pair of counterbores or recesses  16 B formed in the outboard surface of the inboard leg  16  of the caliper  12 . The actuation means  50 , shown in this embodiment as being a hydraulic actuation means, in operable to move the pistons  52  in the outboard direction within the recess  16 B (toward the left when viewing FIG. 3) when operated. However, other types of actuation means  50 , such as for example, electrical and mechanical types, can be used if desired. 
     The prior art disc brake assembly  10  also includes a dust boot seal  56  and an annular fluid seal  58 . The dust boot seal  56  is formed from a flexible material and has a first end which engages an outboard end of the recess  16 B. A second end of the dust boot seal  56  engages an annular groove formed in an outer side wall of the associated piston  52 . A plurality of flexible convolutions are provided in the dust boot seal  56  between the first and second ends thereof. The dust boot seal  56  is provided to prevent water, dirt, and other contaminants from entering into the recess  16 B. The fluid seal  58  is preferably disposed in an annular groove formed in a side wall of the recesses  16 B and engages the outer side wall of the associated piston  52 . The fluid seal  58  is provided to define a sealed hydraulic actuator chamber  60 , within which the pistons  52  are disposed for sliding movement. Also, the fluid seal  58  is designed to function as a “roll back” seal to retract the pistons  52  within the recesses  16 B (toward the right when viewing FIG. 3) when a brake pedal of the vehicle is released. 
     The disc brake assembly  10  further includes a rotor, indicated generally at  70 , which is connected to a wheel (not shown) of the vehicle for rotation therewith. The illustrated rotor  70  is ventilated and includes a pair of opposed friction plates  72  and  74  which are spaced apart from one another by a plurality of intermediate ribs or posts  76  in a known manner. The rotor  70  extends radially outwardly between the inboard friction pad  30  and the outboard friction pad  40 . The entire rotor  70 , including the two friction plates  72  and  74  and the intermediate ribs  76 , may be cast as a single piece if desired. 
     The rotor  70  further includes an inner mounting flange portion  78  connected to the friction plate  74  by a circumferential wall or hat portion  80 . The inner mounting flange portion  78  includes a centrally located pilot hole  78 A which defines an axis of the rotation for the rotor  70 , and a plurality of lug bolt receiving holes (five of such lug bolt receiving holes are shown in FIG.  1 ), equally spaced circumferentially on the rotor  70  about the pilot hole  78 A. A lug bolt  82  extends through each of the lug bolt receiving holes for mounting and securing the rotor  70  to the vehicle wheel for rotation therewith. 
     When it is desired to actuate the disc brake assembly  10  to slow or stop the rotation of the rotor  70  and the vehicle wheel associated therewith, the driver of the vehicle depresses the brake pedal. In a manner which is well known in the art, the depression of the brake pedal causes pressurized hydraulic fluid to be introduced into the chambers  60 . Such pressurized hydraulic fluid urges the associated pistons  52  in the outboard direction (toward the left when viewing FIG. 3) into engagement with the backing plate  32  of the inboard brake shoe  30 . As a result, the friction pad  34  of the inboard brake shoe  30  is moved into frictional engagement with the inboard friction plate  72  of the rotor  70 . 
     At the same time, the caliper  12  slides on the pins  20  in the inboard direction (toward the right when viewing FIG. 3) such that the outboard leg  14  thereof moves the friction pad  44  of the outboard brake shoe  40  into frictional engagement with the outboard friction plate  74  of the rotor  70 . As a result, the opposed friction plates  72  and  74  of the rotor  70  are frictionally engaged by the friction pads  34  and  44 . The structure and operation of the disc brake assembly  10  thus far described is conventional in the art. 
     Turning now to FIGS. 4 and 5 and using like reference numbers to indicate corresponding parts, there is illustrated a first embodiment of an improved structure for a caliper, indicated generally at  100 , in accordance with this invention which can be used in place of the conventional caliper  12  of the prior art disc brake assembly  10  illustrated and described above in connection with FIGS. 1 through 3. Although the caliper  100  of this invention will be described and illustrated in conjunction with the particular prior art vehicle disc brake assembly  10  structure diclosed herein, it will be appreciated that it may be used in conjunction with other kinds of disc brake assembly structures. 
     The caliper  100  is preferably a fiber reinforced caliper formed from aluminum or alloys thereof and includes an inboard leg portion  16  and an outboard leg portion  14  which are interconnected by an intermediate bridge portion  18 . More preferably, the caliper  100  is made from aluminum, such as for example, A354, A356, or A357, and is reinforced with one or more preforms or segments containing individual strands of ceramic fibers. The preforms are preferably formed from chopped alumina oxide fibers and are extruded or otherwise preformed into the predetermined preforms and are selectively disposed in a casting mold and molded integrally in situ therewith the aluminum caliper body during a casting process. The individual strands of the ceramic fibers in the preforms are preferably alumina oxide (Al 2 O 3 ) ceramic fibers. One example of suitable ceramic fibers are Nextel® ceramic fibers manufactured by Minnesota Mining and Manufacturing Company (a.k.a. 3M Corporation), of Saint Paul, Minn. Alternatively, the caliper  100  can be formed from other metals, such as nodular iron, or a combination of two different metals, such as for example, an aluminum based metal matrix composite (MMC) containing silicon carbide particulate reinforcement, aluminum oxide fibers, aluminum oxide chopped fibers and aluminum. 
     As shown in FIGS. 4 and 5, the caliper  100  includes three preforms  102 ,  104  and  106 . The preform  102  has a generally uniform cross-sectional shape and is preferably disposed near the side  18 B of the bridge  18  of the caliper  100 . In the illustrated embodiment, the preform  102  has a generally square shape; however, the shape of the preform  102  can be of any suitable shape, such as for example, rectangular, circular, and triangular and/or can be uniform or non-uniform. 
     The preform  102  preferably extends across the entire axial width of the bridge  18  of the caliper  100  extending from the outboard leg  14  to the inboard leg  16 . The individual strands of the ceramic fibers  102 B (two of such strands  102 B shown in FIG. 4 by a dashed line) in the preform  102  are preferably oriented in an axial direction as indicated by the arrow  102 A and in parallel relationship with an axis X of the caliper  100 . 
     The preform  104  has a generally uniform cross-sectional shape and is preferably disposed near the side  18 A of the bridge  18  of the caliper  100 . The preform  104  preferably extends across the entire axial width of the bridge  18  of the caliper  100  extending from the outboard leg  14  to the inboard leg  16 . The individual strands of the ceramic fibers  104 B (two of such strands  104 B shown in FIG. 4 by a dashed line) in the preform  104  are preferably oriented in an axial direction as indicated by the arrow  104 A and in parallel relationship with the axis X of the caliper  100 . 
     The preform  106  has a generally uniform cross-sectional shape and is preferably disposed generally intermediate the bores  16 B of the caliper  100 . The preform  106  extends across a portion of the bridge  18  of the caliper  100  extending from the inboard leg  16  toward the outboard leg  14 . The individual strands of the ceramic fibers  106 B (two of such strands  106 B shown in FIG. 4 by a dashed line) in the preform  106  are preferably oriented in an axial direction as indicated by the arrow  106 A and in parallel relationship with the axis X of the caliper  100 . Alternatively, the shape, location and/or number of one or more of the preforms  102 ,  104  and  106  of the caliper  100  can be other than illustrated if so desired. 
     Turning now to FIGS. 6 and 7 and using like reference numbers to indicate corresponding parts, there is illustrated a second embodiment of an improved structure for a caliper, indicated generally at  110 , in accordance with this invention which can be used in place of the conventional caliper  12  of the prior art disc brake assembly  10  illustrated and described above in connection with FIGS. 1 through 3. Although the caliper  110  of this invention will be described and illustrated in conjunction with the particular prior art vehicle disc brake assembly  10  structure disclosed herein, it will be appreciated that it may be used in conjunction with other kinds of disc brake assembly structures. 
     The caliper  110  is preferably a fiber reinforced caliper formed from aluminum or alloys thereof and includes an inboard leg portion  16  and an outboard leg portion  14  which are interconnected by an intermediate bridge portion  18 . More preferably, the caliper  110  is made from aluminum, such as for example, A354, A356, or A357, and is reinforced with one or more preforms or segments containing individual strands of ceramic fibers. The preforms are preferably formed from chopped alumina oxide fibers and are extruded or otherwise preformed into the predetermined preforms and are selectively disposed in a casting mold and molded integrally in situ therewith the aluminum caliper body during a casting process. The individual strands of the ceramic fibers are preferably alumina oxide (Al 2 O 3 ) ceramic fibers. One example of suitable ceramic fibers are Nextel® ceramic fibers manufactured by Minnesota Mining and Manufacturing Company (a.k.a. 3M Corporation), of Saint Paul, Minn. Alternatively, the caliper  100  can be formed from other metals, such as nodular iron, or a combination of two different metals, such as for example, an aluminum based metal matrix composite (MMC) containing silicon carbide particulate reinforcement, aluminum oxide fibers, and aluminum. 
     As shown in FIGS. 6 and 7, the caliper  110  includes three preforms  112 ,  114  and  116 . The preform  112  has a generally square cross-sectional shape and is preferably disposed near the side  18 B of the bridge  18  thereof the caliper  110 . The preform  112  preferably extends across the entire axial width of the bridge  18  of the caliper  110  extending from the outboard leg  14  to the inboard leg  16 . The individual strands of the ceramic fibers  112 B (two of such strands  112 B shown in FIG. 6 by a dashed line) in the preform  112  are preferably oriented in a direction as indicated by the arrow  112 A and at an angle B 1  with an axis X of the caliper  110 . The angle B 1  is in the range from about 15 degrees to about 75 degrees. More preferably, the angle B 1  is in the range from about 35 degrees to about 55 degrees. In the illustrated embodiment, the angle B 1  is about 45 degrees. 
     The preform  114  has a generally uniform square cross-sectional shape and is preferably disposed near the side  18 A of the bridge  18  of the caliper  110 . The preform  114  preferably extends across the entire axial width of the bridge  18  of the caliper  110  extending from the outboard leg  14  to the inboard leg  16 . The individual strands of the ceramic fibers  114 B (two of such strands  114 B shown in FIG. 6 by a dashed line) in the preform  114  are preferably oriented in a direction as indicated by the arrow  114 A and at an angle B 2  with the axis X of the caliper  110 . The angle B 2  is in the range from about 15 degrees to about 75 degrees. More preferably, the angle B 2  is in the range from about 35 degrees to about 55 degrees. In the illustrated embodiment, the angle B 2  is about 45 degrees. In the illustrated embodiment, the angles B 1  and B 2  are shown as being the same. However, the angles B 1  and B 2  can be different from each other if so desired. 
     The preform  116  has a generally uniform cross-sectional shape and is preferably disposed generally intermediate the bores  16 B of the caliper  110 . The preform  106  extends across a portion of the bridge  18  of the caliper  110  extending from the inboard leg  16  toward the outboard leg  14 . The individual strands of the ceramic fibers  116 B (two of such strands  116 B shown in FIG. 6 by a dashed line) in the preform  116  are preferably oriented in an axial direction as indicated by the arrow  116 A and in particular relationship with the axis X of the caliper  110 . Alternatively, the shape, location and/or number of one or more of the preforms  112 ,  114  and  116  of the caliper  110  can be other than illustrated if so desired. 
     Turning now to FIGS. 8 and 9 and using like reference numbers to indicate corresponding parts, there is illustrated a third embodiment of an improved structure for a caliper, indicated generally at  120 , in accordance with this invention which can be used in place of the conventional caliper  12  of the prior art disc brake assembly  10  illustrated and described above in connection with FIGS. 1 through 3. Although the caliper  120  of this invention will be described and illustrated in conjunction with the particular prior art vehicle disc brake assembly  10  structure disclosed herein, it will be appreciated that it may be used in conjunction with other kinds of disc brake assembly structures. 
     The caliper  120  is preferably a fiber reinforced caliper formed from aluminum or alloys thereof and includes an inboard leg portion  16  and an outboard leg portion  14  which are interconnected by an intermediate bridge portion  18 . More preferably, the caliper  120  is made from aluminum and is reinforced with one or more preforms or segments containing individual strands of aluminum oxide ceramic fibers. The preforms are preferably formed from chopped alumina oxide fibers and are extruded or otherwise preformed into the predetermined preforms and are selectively disposed in a casting mold and molded integrally in situ therewith the aluminum caliper body during a casting process. Alternatively, the caliper  120  can be formed from other metals, such as nodular iron, or a combination of two different metals, such as for example, an aluminum based metal matrix composite (MMC) containing silicon carbide particulate reinforcement, aluminum oxide fibers, and aluminum. 
     As shown in FIGS. 8 and 9, the caliper  120  includes three preforms  122 ,  124  and  126 . The preform  122  has a generally uniform cross-sectional shape and is preferably disposed near the side  18 B of the bridge  18  thereof the caliper  120 . The preform  122  preferably extends across the entire axial width of the bridge  18  of the caliper  120  extending from the outboard leg  14  to the inboard leg  16 . The individual strands of the ceramic fibers  122 B (two of such strands  122 B shown in FIG. 8 by a dashed line) in the preform  122  are preferably oriented in a direction as indicated by the arrow  122 A and an angle C 1  with an axis X of the caliper  110 . The angle C 1  is in the range from about 15 degrees to about 75 degrees. More preferably, the angle C 1  is in the range from about 35 degrees to about 55 degrees. In the illustrated embodiment, the angle C 1  is about 45 degrees. 
     The preform  124  has a generally uniform cross-sectional shape and is preferably disposed near the side  18 A of the bridge  18  of the caliper  120 . The preform  124  preferably extends across the entire axial width of the bridge  18  of the caliper  120  extending from the outboard leg  14  to the inboard leg  16 . The individual strands of the ceramic fibers  124 B (two of such strands  124 B shown in FIG. 8 by a dashed line) in the preform  124  are preferably oriented in a direction as indicated by the arrow  124 A and at an angle C 2  with the axis X of the caliper  120 . The angle C 2  is in the range from about 15 degrees to about 75 degrees. More preferably, the angle C 2  is in the range from about 35 degrees to about 55 degrees. In the illustrated embodiment, the angle C 2  is about 45 degrees. 
     The preform  126  has a generally uniform cross-sectional shape and is preferably disposed generally intermediate the bores  16 B of the caliper  120 . The preform  126  extends across a portion of the bridge  18  of the caliper  120  extending from the inboard leg  16  toward the outboard leg  14 . The individual strands of the ceramic fibers  126 B (two of such strands  126 B shown in FIG. 8 by a dashed line) in the preform  126  are preferably oriented in an axial direction as indicated by the arrow  126 A and in parallel relationship with the axis X of the caliper  20 . Alternatively, the shape, location and/or number of one or more of the preforms  122 ,  124  and  126  of the caliper  120  can be other than illustrated if so desired. 
     Turning now to FIGS. 10 and 11 and using like reference numbers to indicate corresponding parts, there is illustrated a fourth embodiment of an improved structure for a caliper, indicated generally at  130 , in accordance with this invention which can be used in place of the conventional caliper  12  of the prior art disc brake assembly  10  illustrated and described above in connection with FIGS. 1 through 3. Although the caliper  130  of this invention will be described and illustrated in conjunction with the particular prior art vehicle disc brake assembly  10  structure disclosed herein, it will be appreciated that it may be used in conjunction with other kinds of disc brake assembly structures. 
     The caliper  130  is preferably a fiber reinforced caliper formed from aluminum or alloys thereof and includes an inboard leg portion  16  and an outboard leg portion  14  which are interconnected by an intermediate bridge portion  18 . More preferably, the caliper  130  is made from aluminum and is reinforced with one or more preforms or segments containing individual strands of aluminum oxide ceramic fibers. The preforms are preferably formed from chopped aluminum oxide fibers and are extruded or otherwise preformed into the predetermined preforms and are selectively disposed in a casting mold and molded integrally in situ therewith the aluminum caliper body during a casting process. Alternatively, the caliper  130  can be formed from other metals, such as nodular iron, or a combination of two different metals, such as for example, an aluminum based metal matrix composite (MMC) containing silicon carbide particulate reinforcement, aluminum oxide fibers, and aluminum. 
     As shown in FIGS. 10 and 11, the caliper  130  includes three preforms  132 ,  134  and  136 . The preform  132  has a generally uniform cross-sectional shape and is preferably disposed near the side  18 B of the bridge  18  of the caliper  130 . The preform  132  preferably extends across the entire axial width of the bridge  18  of the caliper  130  extending from the outboard leg  14  to the inboard leg  16 . The individual strands of the ceramic fibers  132 B (two of such strands  132 B shown in FIG. 10 by a dashed line) in the preform  132  are preferably oriented in an axial direction as indicated by the arrow  132 A and in parallel relationship with an axis X of the caliper  130 . 
     The preform  134  has a generally uniform cross-sectional shape and is preferably disposed near the side  18 A of the bridge  18  thereof the caliper  130 . The preform  134  preferably extends across the entire axial width of the bridge  18  of the caliper  130  extending from the outboard leg  14  to the inboard leg  16 . The individual strands of the ceramic fibers  134 B (two of such strands  134 B shown in FIG. 10 by a dashed line) in the preform  134  are preferably oriented in an axial direction as indicated by the arrow  134 A and in parallel relationship with the axis X of the caliper  130 . 
     The preform  136  is optional and has a generally uniform cross-sectional shape and is preferably disposed at an outer side of the bridge  18  of the caliper at the juncture of transition of the bridge  18  to the outboard leg  14 . The preform  136  includes opposed ends  136 B which are disposed adjacent outer ends  132 B and  134 B of the preforms  132  and  134 , respectively. The individual strands of the ceramic fibers  136 B (two of such strands  136 B shown in FIG. 10 by a dashed line) in the preform  136  are preferably oriented in a direction as indicated by the arrow  136 A and in crossing or perpendicular relationship with the axis X of the caliper  130 . Alternatively, the shape, location and/or number of one or more of the preforms  132 ,  134  and  136  of the caliper  130  can be other than illustrated if so desired. Also, the caliper  130  could include additional preforms. For example, the caliper  130  could include a preform similar to the preform  106  shown and described above in connection with FIGS. 4 and 5. 
     Turning now to FIGS. 12 and 13 and using like reference numbers to indicate corresponding parts, there is illustrated a fifth embodiment of an improved structure for a caliper, indicated generally at  140 , in accordance with this invention which can be used in place of the conventional caliper  12  of the prior art disc brake assembly  10  illustrated and described above in connection with FIGS. 1 through 3. Although the caliper  140  of this invention will be described and illustrated in conjunction with the particular prior art vehicle disc brake assembly  10  structure disclosed herein, it will be appreciated that it may be used in conjunction with other kinds of disc brake assembly structures. 
     The caliper  140  is preferably a fiber reinforced caliper formed from aluminum or alloys thereof and includes an inboard leg portion  16  and an outboard leg portion  14  which are interconnected by an intermediate bridge portion  18 . More preferably, the caliper  140  is made from aluminum and is reinforced with one or more preforms or segments containing individual strands of aluminum oxide ceramic fibers, and chopped aluminum oxide ceramic fibers. The preforms are preferably formed from chopped aluminum oxide fibers and are extruded or otherwise preformed into the predetermined preforms and are selectively disposed in a casting mold and molded integrally in situ therewith the aluminum caliper body during a casting process. One example of suitable chopped ceramic fibers are Saffil® high aluminum ceramic fibers manufactured by Saffil Limited, of the United Kingdom. The preforms are formed by an extrusion process or other suitable process which combines the two different fibers into an unitary preform which is then selectively disposed in a casting mold and molded integrally in situ therewith the aluminum caliper body during a casting process. Alternatively, the caliper  140  can be formed from other metals, such as nodular iron, or a combination of two different metals, such as for example, an aluminum based metal matrix composite (MMC) containing silicon carbide particulate reinforcement, aluminum oxide fibers, and aluminum. 
     As shown in FIGS. 12 and 13, the caliper  140  includes two preforms  142  and  144 . The preform  142  has a generally uniform cross-sectional shape and is preferably disposed near the side  18 B of the bridge  18  of the caliper  140 . The preform  142  preferably extends across the entire axial width of the bridge  18  of the caliper  140  extending from the outboard leg  14  to the inboard leg  16 . The preform  142  includes a first portion  142 A having individual strands of ceramic fibers  142 C (two of such strands  142 C shown in FIG. 12 each by a single dot), and a second portion  142 B having chopped ceramic fibers  142 D (such chopped ceramic fibers shown in FIG. 12 by dots). Preferably, the preform  142  is oriented at an angle D 1  with respect to the axis X of the caliper  140 . The angle D 1  is in the range from about 5 degrees to about 25 degrees. More preferably, the angle D 1  is in the range from about 10 degrees to about 20 degrees. In the illustrated embodiment, the angle D 1  is about 15 degrees. The individual strands of the ceramic fibers  142 C in the first portion  142 A of the preform  142  are preferably oriented in a generally axial direction and in a generally parallel relationship with an axis X of the caliper  140 . The chopped ceramic fibers  142 D in the second portion  142 B of the preform  142  are preferably oriented in a generally axial direction and in a generally parallel relationship with the axis X of the caliper  140 . 
     The preform  144  has a generally uniform cross-sectional shape and is preferably disposed near the side  18 A of the bridge  18  thereof the caliper  140 . The preform  144  preferably extends across the entire axial width of the bridge  18  of the caliper  140  extending from the outboard leg  14  to the inboard leg  16 . The preform  144  includes a first portion  144 A having individual strands of ceramic fibers  144 C (two of such strands  144 C shown in FIG. 12 each by a single dot), and a second portion  144 B having chopped ceramic fibers  144 D  136 B (such chopped ceramic fibers shown in FIG. 12 by dots). Preferably, the preform  144  is oriented at an angle (not shown) with respect to the axis X of the caliper  140 . The angle is preferably in the range from about 5 degrees to about 25 degrees. More preferably, the angle is in the range from about 10 degrees to about 20 degrees. In the illustrated embodiment, the angle is about 15 degrees. The individual strands of the ceramic fibers  144 C in the first portion  144 A of the preform  144  are preferably oriented in a generally axial direction and in a generally parallel relationship with the axis X of the caliper  140 . The chopped ceramic fibers  144 D in the second portion  144 B of the preform  144  are preferably oriented in a generally axial direction and in a generally parallel relationship with the axis X of the caliper  140 . Alternatively, the shape, location and/or number of one or both of the preforms  142  and  144  of the caliper  140  can be other than illustrated if so desired. Also, the caliper  140  could include additional preforms of a similar or different construction. 
     Turning now to FIGS. 14 and 15 and using like reference numbers to indicate corresponding parts, there is illustrated a sixth embodiment of an improved structure for a caliper, indicated generally at  150 , in accordance with this invention which can be used in place of the conventional caliper  12  of the prior art disc brake assembly  10  illustrated and described above in connection with FIGS. 1 through 3. Although the caliper  150  of this invention will be described and illustrated in conjunction with the particular prior art vehicle disc brake assembly  10  structure disclosed herein, it will be appreciated that it may be used in conjunction with other kinds of disc brake assembly structures. 
     The caliper  150  is preferably a metal reinforced caliper formed from aluminum or alloys thereof and includes an inboard leg portion  16  and an outboard leg portion  14  which are interconnected by an intermediate bridge portion  18 . More preferably, the caliper  150  is made from aluminum and is reinforced with one or more preforms or segments formed from a powdered metal. A suitable powdered metal preform is preferably formed from steel, stainless steel, molybdenum, or Inconel® manufactured by Inco Alloys International, Inc., of Huntington, W. Va. The preforms are formed by a molding process of other suitable process which produces the preform which is then selectively disposed in a casting mold and molded integrally in situ therewith the aluminum caliper body during a casting process. Alternatively, the caliper  150  can be formed from other metals, such as nodular iron, or a combination of two different metals, such as for example, an aluminum based metal matrix composite (MMC) containing silicon carbide particulate reinforcement, aluminum oxide fibers, and aluminum. 
     As shown in FIGS. 14 and 15, the caliper  150  includes three preforms  152 ,  154  and  156 . The preform  152  has a non-uniform or varying cross-sectional shape and is preferably disposed near the side  18 B of the bridge  18  and adjacent an underside  18 C of the bridge  18  of the caliper  150 . The preform  152  preferably extends across the entire axial width of the bridge  18  of the caliper  150  extending from the inboard leg  16  and into a portion of the outboard leg  14 . In particular, the preform  152  includes an outer end portion  152 A which extends radially downwardly into a portion of the outboard leg  14  of the caliper  150 . 
     The preform  154  has a non-uniform or varying cross-sectional shape and is preferably disposed near the side  18 A of the bridge  18  and adjacent the underside  18 C of the bridge  18  of the caliper  150 . The preform  154  preferably extends across the entire axial width of the bridge  18  of the caliper  150  extending from the inboard leg  16  and into a portion of the outboard leg  14 . In particular, the preform  154  includes an outer end portion  154 A which extends radially downwardly into a portion of the outboard leg  14  of the caliper  150 . 
     The preform  156  is optional and is disposed generally intermediate the bores  16 B of the caliper  150  and adjacent the underside  18 C of the bridge  18  of the caliper  150 . The preform  156  extends across a portion of the bridge  18  of the caliper  150  extending from the inboard leg  16  toward the outboard leg  14 . Alternatively, the shape, location and/or number of one or more of the preforms  152 ,  154  and  156  of the caliper  150  can be other than illustrated if so desired. 
     Turning now to FIGS. 16 and 17 and using like reference numbers to indicate corresponding parts, there is illustrated a seventh embodiment of an improved structure for a caliper, indicated generally at  160 , in accordance with this invention which can be used in place of the conventional caliper  12  of the prior art disc brake assembly  10  illustrated and described above in connection with FIGS. 1 through 3. Although the caliper  150  of this invention will be described and illustrated in conjunction with the particular prior art vehicle disc brake assembly  10  structure disclosed herein, it will be appreciated that it may be used in conjunction with other kinds of disc brake assembly structures. 
     The caliper  160  is preferably a metal reinforced caliper formed from aluminum or alloys thereof and includes an inboard leg portion  16  and an outboard leg portion  14  which are interconnected by an intermediate bridge portion  18 . More preferably, the caliper  160  is made from aluminum and is reinforced with one or more preforms or segments formed from powdered metal. A suitable powdered metal preform is preferably formed from steel, stainless steel, molybdenum, or Inconel®. The preforms are formed by a molding process or other suitable process which produces the preform which is then selectively disposed in a casting mold and molded integrally in situ therewith the aluminum caliper body during a casting process. Alternatively, the caliper  160  can be formed from other metals, such as nodular iron, or a combination of two different metals, such as for example, an aluminum based metal matrix composite (MMC) containing silicon carbide particulate reinforcement, aluminum oxide fibers, and aluminum. 
     As shown in FIGS. 16 and 17, the caliper  160  includes three preforms  162 ,  164  and  166 . The preform  162  includes a plurality of pockets or open cavities  162 A separated from each other by a wall  162 B. The illustrated preform  162  is provided with five pockets  162 A and four walls  162 B. The preform  162  has a non-uniform cross-sectional shape and is preferably disposed near the side  18 B of the bridge  18  and adjacent an underside  18 C of the bridge  18  of the caliper  160 . The preform  162  preferably extends across the entire axial width of the bridge  18  of the caliper  160  extending from the inboard leg  16  and into a portion of the outboard leg  14 . In particular, the preform  162  includes an outer end portion  162 C which extends radially downwardly into a portion of the outboard leg  14  of the caliper  160 . In the illustrated embodiment, the outer end portion includes a pocket  162 D. 
     The preform  164  includes a plurality of pockets or open cavities (not shown) separated from each other by a wall (not shown). The preform  164  has a non-uniform cross-sectional shape and is preferably disposed near the side  18 A of the bridge  18  and adjacent an underside  18 C of the bridge  18  of the caliper  160 . The preform  164  preferably extends across the entire axial width of the bridge  18  of the caliper  160  extending from the inboard leg  16  and into a portion of the outboard  14 . In particular, the preform  164  includes an outer end portion  164 C which extends radially downwardly into a portion of the outboard leg  14  of the caliper  160 . 
     The preform  166  is optional and is preferably disposed generally intermediate the bores  16 B of the caliper  160  and adjacent the underside  18 C of the bridge  18  of the caliper  160 . The preform  166  extends across a portion of the bridge  18  of the caliper  160  extending from the inboard leg  16  toward the outboard leg  14 . The preform  166  can include one or more pockets (not shown) similar to that of preform  162  or can be similar to any of the other preforms described and illustrated hereinbefore or hereinafter. Alternatively, the shape, location and/or number of one or more of the performs  162 ,  164  and  166  of the caliper  160  can be other than illustrated if so desired. 
     Turning now to FIGS. 18 and 19 and using like reference numbers to indicate corresponding parts, there is illustrated an eighth embodiment of an improved structure for a caliper, indicated generally at  170 , in accordance with this invention which can be used in place of the conventional caliper  12  of the prior art disc brake assembly  10  illustrated and described above in connection with FIGS. 1 through 3. Although the caliper  170  of this invention will be described and illustrated in conjunction with the particular prior art vehicle disc brake assembly  10  structure disclosed herein, it will be appreciated that it may be used in conjunction with other kinds of disc brake assembly structures. 
     The caliper  170  is preferably a fiber reinforced caliper formed from aluminum or alloys thereof and includes an inboard leg portion  16  and an outboard leg portion  14  which are interconnected by an intermediate bridge portion  18 . More preferably, the caliper  170  is made from aluminum and is reinforced with one preform or segment containing individual strands of aluminum oxide ceramic fibers, and chopped aluminum oxide fibers. The preforms are preferably formed from chopped alumina oxide fibers and are formed by an extrusion process or other suitable process which enables the two different fibers to be combined into an unitary perform which is then selectively disposed in a casting mold and molded integrally in situ therewith the aluminum caliper body during a casting process. Alternatively, the caliper  170  can be formed from other metals, such as nodular iron, or a combination of two different metals, such as for example, an aluminum based metal matrix composite (MMC) containing silicon carbide particulate reinforcement, aluminum oxide fibers, and aluminum. 
     As shown in FIGS. 18 and 19, the caliper  170  includes a single preform  172 . The preform  172  has a generally uniform cross-sectional shape and preferably spans or covers substantially the entire portion of the bridge  18  of the caliper  140 . Alternatively, the preform  172  can cover the entire portion of the bridge  18  of the caliper  170  or can cover substantially less than the entire portion of the bridge  18  of the caliper  170 . The preform  172  includes a first or main body portion  174  which preferably includes chopped fibers  174 A (such chopped fibers  174 A shown in only a portion of FIG. 19 by dots), and a plurality of second portions including individual strands of fibers  176 J (such individual strands of fibers  176 J shown in FIG. 18 only portion  176 H by a dashed line) which are selectively located within the first portion  174 . As shown in this embodiment, the preform  172  includes nine second portions indicated at  176 A- 176 I. Each of the second portions  176 A- 176 I is preferably located below the adjacent outer surface of the first portion  174 . In this embodiment, the secondary portions  176 A- 176 H preferably extend across the entire axial width of the bridge  18  of the caliper  170  extending from the outboard leg  14  to the inboard leg  16  thereof. The secondary portion  176 I extends across a portion of the bridge  18  of the caliper  170  extending from the inboard leg  16  toward the outboard leg  14 . Alternatively, the shape, location, and or number of the preform  172 , the first portion  174 , and the second portions  176 A- 176 I can be other than illustrated if so desired. For example, the preform  172  could be divided into two or more individual preform sections. 
     Turning now to FIGS. 20 and 21 and using like reference numbers to indicate corresponding parts, there is illustrated a ninth embodiment of an improved structure for a caliper, indicated generally at  180 , in accordance with this invention which can be used in place of the conventional caliper  12  of the prior art disc brake assembly  10  illustrated and described above in connection with FIGS. 1 through 3. Although the caliper  180  of this invention will be described and illustrated in conjunction with the particular prior art vehicle disc brake assembly  10  structure disclosed herein, it will be appreciated that it may be used in conjunction with other kinds of disc brake assembly structures. 
     The caliper  180  is preferably a fiber reinforced caliper formed from aluminum or alloys thereof and includes an inboard leg portion  16  and an outboard leg portion  14  which are interconnected by an intermediate bridge portion  18 . More preferably, the caliper  180  is made from aluminum and is reinforced with one or more preforms or segments containing individual strands of ceramic fibers and chopped ceramic fibers. The preforms are preferably formed from chopped alumina oxide fibers and are formed by an extrusion process or other suitable process which combines the two different fibers into an unitary preform which is then selectively disposed in a casting mold and molded integrally in situ therewith the aluminum caliper body during a casting process. Alternatively, the caliper  180  can be formed from other metals, such as nodular iron, or a combination of two different metals, such as for example, an aluminum based metal matrix composite (MMC) containing silicon carbide particulate reinforcement, aluminum oxide fibers, and aluminum. 
     As shown in FIGS. 20 and 21, the caliper  180  includes two preforms  182  and  184 . The preform  182  has a generally uniform cross-sectional shape and is preferably disposed near the side  18 B of the bridge  18  of the caliper  140 . The preform  182  preferably extends across the entire axial width of the bridge  18  of the caliper  180  extending from the outboard leg  14  to the inboard leg  16 . 
     The preform  182  includes a first portion  186  including individual strands of the ceramic fibers  186 A (one of such individual strands of fibers  186 A shown in FIG. 20 by a dashed line), and a second portion  188  including chopped ceramic fibers  188 A (such chopped fibers  188 AB shown in FIG. 18 only in a portion thereof by dots). The individual strands of the ceramic fibers  186 A in the first portion  186  of the preform  182  are preferably oriented in a generally axial direction and in a generally parallel relationship with an axis X of the caliper  180 . The chopped fibers  188 A in the second portion  188  of the preform  182  are preferably oriented in a generally axial direction and in a generally parallel relationship with the axis X of the caliper  180 . 
     The preform  182  is preferably provided with one or more through or blind openings. In the illustrated embodiment, the preform  182  is provided with two through openings  190  and  192  which extend completely through the preform  182 . In the illustrated embodiment, the openings  190  and  192  are formed in the second portion  188  of the preform  182 . As will be described below, the openings  190  and  192  are effective to locate and maintain the preform  182  in a desired position in a mold apparatus during a molding process of the caliper  180 . Alternatively, the shape, depth, number and/or the location of the openings  190  and  192  can be other than illustrated if desired. 
     The preform  184  has a generally uniform cross-sectional shape and is preferably disposed near the side  18 A of the bridge  18  of the caliper  140 . The preform  184  preferably extends across the entire axial width of the bridge  18  of the caliper  180  extending from the outboard leg  14  to the inboard leg  16 . 
     The preform  184  includes a first portion  194  including individual strands of the ceramic fibers  194 A (one of such individual strands of fibers  194 A shown in FIG. 20 by a dashed line), and a second portion  196  including chopped ceramic fibers  196 A (such chopped fibers  196 A shown in FIG. 20 only in a portion thereof by dots). The individual strands of the ceramic fibers  194 A in the first portion  194  of the preform  184  are preferably oriented in a generally axial direction and in a generally parallel relationship with an axis X of the caliper  180 . The chopped ceramic fibers  196 A in the second portion  196  of the preform  184  are preferably oriented in a generally axial direction and in a generally parallel relationship with the axis X of the caliper  180 . 
     The preform  184  is preferably provided with one or more through or blind openings. In the illustrated embodiment, the preform  184  is provided with two through openings  198  and  200  which extend completely through the preform  182  In the illustrated embodiment, the openings  198  and  200  are formed in the second portion  16  of the preform  184  and have a generally circular shape. As will be described below, the openings  198  and  200  are effective to locate and maintain the preform  184  in a desired position in a mold apparatus during a molding process of the caliper  180 . Alternatively, the shape, depth, number and/or the location of the openings  198  and  200  can be other than illustrated if desired. For example, the preform  184  can include only one opening having a non-circular shape. 
     Referring to FIG. 22, there is illustrated a sectional view of a portion of a molding apparatus, indicated generally at  210 , which can be used to produce the caliper  180 . As shown therein, the mold apparatus  210  includes an upper mold section  212  and a lower mold section  214 . In the illustrated embodiment, the upper mold section  212  includes a plurality of downwardly extending projections  216 . The number of the projections  216  preferably correspond to the number of openings provided in the preforms  182  and  184 . In this embodiment the mold apparatus  210  includes four projections  216  (only two of which are shown in FIG.  22 ), which are operative to extend completely through the associated openings  190  and  192  and  196  and  198  of the preforms  182  and  184 , respectively, and are received in corresponding openings  214 A provided in the lower mold section  214 . Alternatively, the projections  216  could extend less than completely through one or more of the associated openings  190  and  192  and  196  and  198  of the respective preforms  182  and  184  if so desired. As a result, the preforms  182  and  184  are located in the molding apparatus  210  in a predetermined position. Alternatively, the number, length, structure and/or location of the projections  216  can be other than illustrated if so desired. For example, the projections  216  could be upwardly extending projections provided only on the lower mold section  214 , or at least one or more of the projections  216  could be provided on both the upper mold section  212  and the lower mold section  216 . Also, projections (not shown) could be provided on the preforms  182  and  184  and corresponding openings or recesses provided in one or both of the mold sections  214  and  216  for receiving such projections. 
     Turning now to FIG.  23  and using like reference numbers to indicated corresponding parts, there is illustrated a portion of a tenth embodiment of an improved structure for a caliper, indicated generally at  250 , in accordance with this invention which can be used in place of the conventional caliper  12  of the prior art disc brake assembly  10  illustrated and described above in connection with FIGS. 1 through 3. Although the caliper  250  of this invention will be described and illustrated in conjunction with the particular prior art vehicle disc brake assembly  10  structure disclosed herein, it will be appreciated that it may be used in conjunction with other kinds of disc brake assembly structures. As shown therein, the bridge portion  18  of the caliper  250  in this embodiment is reinforced with generally I-shaped preforms or segments  252 . Each of the preforms  252  includes a first portion  252 A having chopped ceramic fibers  252 C (such chopped fibers  252 C shown in FIG. 23 by dots), and a second outer portions  252 B including individual strands of ceramic fibers  252 D (such individual strands of ceramic fibers  252 D shown in FIG. 23 by a dashed line). 
     Turning now to FIG.  24  and using like reference numbers to indicate corresponding parts, there is illustrated an eleventh embodiment of an improved structure for a caliper, indicated generally at  220 , in accordance with this invention which can be used in place of the conventional caliper  12  of the prior art disc brake assembly  10  illustrated and described above in connection with FIGS. 1 through 3. Although the caliper  220  of this invention will be described and illustrated in conjunction with the particular prior art vehicle disc brake assembly  10  structure disclosed herein, it will be appreciated that it may be used in conjunction with other kinds of disc brake assembly structures. 
     The caliper  220  is preferably a reinforced caliper formed from aluminum or alloys thereof and includes an inboard leg portion  16  and an outboard leg portion  14  which are interconnected by an intermediate bridge portion  18 . More preferably, the caliper  220  is made from aluminum and is reinforced with one or more preforms or segments formed from powdered metal. A suitable powdered metal preform is preferably formed from steel, stainless steel, molybdenum, and Inconel®. The preforms are formed by a molding process or other suitable process which produces the preform which is then selectively disposed in a casting mold and molded integrally in situ therewith the aluminum caliper body during a casting process. Alternatively, the caliper  240  can be formed from other metals, such as nodular iron, or a combination of two different metals, such as for example, an aluminum based metal matrix composite (MMC) containing silicon carbide particulate reinforcement, aluminum oxide fibers, and aluminum. 
     As shown in FIG. 24, the caliper  220  includes a first preform  224  and a second preform  226 . The first preform  224  is a reinforced preform preferably formed from ceramic particles. The second preform  226  is a reinforced preform preferably formed from the ceramic fibers. The reinforced preforms  224  and  226  are preferably formed by a molding process or other suitable process which produces the preforms which are then selectively disposed in a casting mold and molded integrally in situ therewith the aluminum caliper body during a casting process. Alternatively, the caliper  220  can be formed from other metals, such as nodular iron, or a combination of two different metals, such as for example, an aluminum based metal matrix composite (MMC) containing silicon carbide particulate reinforcement, aluminum oxide fibers, and aluminum. 
     As shown in FIG. 24, the preform  224  has a generally C-shaped cross-sectional shape and includes a first generally flat surface  224 A, a second generally upwardly extending surface  224 B, a third generally flat surface  224 C, and a fourth generally flat surface  224 D. In the illustrated embodiment, the preform includes a generally curved transition surface  224 E between the first second surface  224 B and the third surface  224 C, and a generally curved transition surface  224 F between the third surface  224 C and the fourth surface  224 D. The first surface  224 A defines a shoulder, and the fourth surface  224 D defines a portion of the counterbore  16 B. 
     The preform  226  has a generally C-shaped cross-sectional shape and includes a first portion  226 A, a second portion  226 B, and a third portion  226 C. In the illustrated embodiment, the first portion  226 A extends radially downwardly into a portion of the outboard leg  14  of the caliper  220 , the second portion  226 B extends across the entire axial width of the bridge  18  of the caliper  220 , and the third portion  226 C extends radially downwardly into a portion of the inboard leg  16  and defines a portion of the counterbore  16 B. Alternatively, the shape, location and/or number of one or more of the preforms  224  and  226  of the caliper  220  can be other than illustrated if so desired. 
     Turning now to FIG.  25  and using like reference numbers to indicate corresponding parts, there is illustrated an twelfth embodiment of an improved structure for a caliper, indicated generally at  240 , in accordance with this invention which can be used in place of the conventional caliper  12  of the prior art disc brake assembly  10  illustrated and described above in connection with FIGS. 1 through 3. Although the caliper  240  of this invention will be described and illustrated in conjunction with the particular prior art vehicle disc brake assembly  10  structure disclosed herein, it will be appreciated that it may be used in conjunction with other kinds of disc brake assembly structures. 
     The caliper  240  is preferably a reinforced caliper formed from aluminum or alloys thereof and includes an inboard leg portion  16  and an outboard leg portion  14  which are interconnected by an intermediate bridge portion  18 . More preferably, the caliper  240  is made from aluminum and is reinforced with one or more preforms or segments formed from a powdered metal. A suitable powdered metal preform is preferably formed from steel, stainless steel, molybdenum, and Inconel®. The preforms are formed by a molding process or other suitable process which produces the preform which is then selectively disposed in a casting mold and molded integrally in situ therewith the aluminum caliper body during a casting process. Alternatively, the caliper  240  can be formed from other metals, such as nodular iron, or a combination of two different metals, such as for example, an aluminum based metal matrix composite (MMC) containing silicon carbide particulate reinforcement, aluminum oxide fibers, and aluminum. 
     As shown in FIG. 25, the caliper  240  includes a preform  242  having a generally C-shaped cross-sectional shape and includes a first portion  242 A, a second portion  242 B, and a third portion  242 C. In the illustrated embodiment, the first portion  242 A extends radially downwardly into a portion of the outboard leg  14  of the caliper  240 , the second portion  242 B extends across the entire axial width of the bridge  18  of the caliper  220 , and the third portion  242 C extends radially downwardly into a portion of the inboard leg  16 . Alternatively, the shape, location and/or number of the preform  242  of the caliper  220  can be other than illustrated if so desired. In this embodiment, the preform  242  is in that part of the casting which is in compression during pressurization of the casting apparatus. 
     While the calipers  100 ,  110 ,  120 ,  130 ,  140 ,  150 ,  160 ,  170 ,  180 ,  210 ,  220  and  240  of this invention have been illustrated and described in connection with a “sliding” caliper type of disc brake assembly, the invention may be used with other types of brake assemblies. For example, the invention may be used in connection with a “fixed” caliper type of disc brake assembly (not shown), or may be used in connection with a drum-in-hat type of disc brake assembly (not shown), wherein the disc brake assembly includes a disc service brake and a drum parking and emergency brake. 
     In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention have been described and illustrated in its preferred embodiments. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.