Snap in ABS exciter ring

1. A disc brake rotor assembly comprising:

a cast iron rotor for rotation about an axis, the cast iron rotor having a cylindrically shaped interior surface and a plurality mutually isolated exciter ring engagement points distributed around the cylindrically shaped interior surface; and

an exciter ring made of a corrosion resistant material, which exhibits a different thermal coefficient of expansion than does the iron of the rotor, which is flattened to define opposite major surfaces and which has a plurality of tangs arranged radially with respect to one another and extending from one major surface for snap fit engagement with the plurality of engagement points on the cylindrically shaped interior surface of the cast iron rotor; and

the snap fit engagement providing resistance to removal of the exciter ring after fitting of the exciter ring to the rotor and preventing clocking of the exciter ring on the rotor even notwithstanding thermally related differential expansion of the cast iron rotor and the exciter ring.

2. A disc brake rotor assembly as set forth in claim 1 , further comprising:

a plurality of indentations in the cylindrically shaped interior surface, the plurality of indentations being coplaner and radially distributed about the cylindrically shaped interior surface to provide a plurality of catches corresponding to the engagement points;

the exciter ring being inserted in an orientation to bring each of the plurality of tangs into alignment with a different one of the plurality of indentations; and

a retaining element projecting outwardly from each tang into engagement with the adjacent indentation to provide a plurality of beads.

3. A disc brake rotor assembly as set forth in claim 1 , further comprising:

a plurality of beads extending away from the cylindrically shaped interior surface, the plurality of beads being coplaner and radially distributed about the cylindrically shaped interior surface to provide the engagement points;

the exciter ring being inserted in an orientation aligning each of the plurality of tangs with a different one of the plurality of beads; and

an opening in each tang for functioning as a catch into which one bead is fitted for retaining the exciter ring in place.

4. A disc brake rotor assembly as set forth in claim 3 , further comprising:

the beads having a beveled surface facing a direction from which the tangs are introduced.

5. A method of fabricating a disc brake rotor assembly, the method comprising the steps of:

providing a rotor having a cylindrically shaped interior surface;

stamping an exciter ring made of a material which is relatively corrosion resistant compared to the rotor, flattened to define opposite major surfaces and provided with radially arranged tangs extending from one

of the major sides of the exciter ring;

fitting the exciter ring onto the rotor with the tangs extending into an interior of the rotor defined by the cylindrically shaped interior surface and into snap fit engagement with the cylindrically shaped interior surface for retention of the exciter ring on the rotor; and

modifying the interior surface to provide a plurality isolated engagement points positioned around the interior surface to allow the each tang to be aligned with an engagement point upon fitting, the tangs and engagement points cooperating to prevent unintended withdrawal of the exciter ring and autorotation of the exciter ring notwithstanding differing differing thermal responses of the rotor and the exciter ring in use.

6. A method of fabricating a disc brake rotor assembly as set forth in claim 5 , wherein the step of providing a rotor includes:

including a plurality of indentations in the cylindrically shaped interior surface, the plurality of indentations being coplaner and radially distributed about the cylindrically shaped interior surface;

positioning the exciter ring to position the tangs into contact with the cylindrically shaped interior surface with each of the plurality of tangs aligned on a different one of the plurality of indentations; and

the step of stamping an exciter ring including providing a cooperating retaining element projecting outwardly from each tang for engagement with its adjacent indentation.

7. A method of fabricating a disc brake rotor assembly as set forth in claim 5 , wherein the step of providing a rotor includes:

casting the rotor in a mold defining a plurality of beads on the cylindrically shaped interior surface, the plurality of beads being coplaner and radially distributed about the cylindrically shaped interior surface;

inserting the exciter ring rotated to bring each of the plurality of tangs into alignment with a different one of the plurality of beads;

providing an opening in each tang as a catch; and

fitting each opening over a different one of the plurality of beads to retain the exciter ring in place.

8. A method of fabricating a disc brake rotor assembly as set forth in claim 7 , further comprising the steps of:

shaping the bead to have a bevel disposed for displacing the tangs upwardly while the tang is initially moved over the bead.

9. A method of fabricating a disc brake rotor assembly as set forth in claim 5 , the method comprising the further steps of providing a bevel on the ring.