Vehicle twist axle assembly

1. A twist axle assembly for a vehicle, comprising:

twist beam of a single integral piece and extending along a length between opposite ends and having an open cross-sectional shape between said ends;

the twist beam being stamped into a U-shape with a middle section which extends in a first direction between a pair of trailing arm sections and wherein each of said trailing arm sections extends at least partially in a second direction that is generally transverse to said first direction to reduce twisting stresses within said trailing arm sections during operation of said twist axle assembly;

a pair of closeout plates joined with said trailing arm sections of said twist beam to close said open cross-sectional shapes of said trailing arm sections; and

each of said closeout plates extending through a curve from one of said ends of said twist beam to said middle section to at least partially close only a portion of said open cross-sectional shape in said middle section.

2. The twist axle assembly as set forth in claim 1 further including at least one component welded to the portion of at least one of said trailing arm sections that extends in said second direction.

3. The twist axle assembly as set forth in claim 2 wherein said at least one component welded to at least one of said trailing arm sections is a wheel carrier.

4. The twist axle assembly as set forth in claim 2 wherein said at least one component welded to at least one of said trailing arm sections is a body mount.

5. The twist axle assembly as set forth in claim 1 wherein each of said closeout plates includes a transition portion which has a U-shaped opening for gradually increasing the torsional stiffness of said twist beam from said middle section to each of said trailing arm sections.

6. The twist axle assembly as set forth in claim 1 wherein said trailing arm sections are curved from said first direction to said second direction.

7. The twist axle assembly as set forth in claim 1 further including a spring seat that is integrally connected as one piece with said twist beam.

8. A method of making a twist axle assembly, comprising the steps of:

preparing a workpiece;

stamping the workpiece into a single piece twist beam with a U-shaped configuration which presents a middle section that extends in a first direction and a pair of trailing arm sections that extend at least partially in a second direction that is generally transverse to the first direction, wherein the twist beam has an open cross-sectional shape along a length thereof; and

fixedly attaching closeout plates with the twist beam to close the open cross-sectional shapes of the trailing arm sections and wherein each of the closeout plates extends through a curve to at least partially close only a portion of the open cross-sectional shape in the middle section.

9. The method as set forth in claim 8 further including the step of welding at least one component to the portion of at least one of the trailing arm sections of the twist beam that extends in the second direction.

10. The method as set forth in claim 9 wherein the step of welding at least one component to at least one of the trailing arm sections of the twist beam is further defined as welding at least one wheel carrier to at least one of the trailing arm sections of the twist beam.

11. The method as set forth in claim 9 wherein the step of welding at least one component to at least one of the trailing arm sections of the twist beam is further defined as welding at least one body mount to at least one of the trailing arm sections of the twist beam.

12. The method as set forth in claim 8 wherein the step of stamping the workpiece further creates at least one spring seat integrally connected with at least one of the trailing arm sections of the twist beam.

13. The method as set forth in claim 8 wherein the closeout plate includes a transitional feature which includes a U-shaped opening for gradually increasing a torsional stiffness of the twist beam from the middle section to the at least one trailing arm section.