A U-Bolt serves in four critical and related roles:

1. Primarily, the U-Bolt provides the force required to clamp the leaf spring and related components firmly together. In addition to the leaf spring, these components include the top plate, axle seat, axle and bottom plate.

2. The properly installed U-Bolt eliminates any flexing of the leaf spring in the area between the U-Bolts. This is particularly critical since the hole for the centerbolt in each leaf acts as a stress concentration which would lead to rapid leaf breakage if spring flexing was not totally eliminated by the U-Bolt clamping force.

3. By firmly clamping the spring to the axle seat the horizontal forces acting on the centerbolt are greatly reduced , which in turn prevents shearing of the centerbolt.

4. Proper clamping of the spring by the U-Bolts provides the desired spring stiffness and contributes to maintaining the vehicle ride height and handling characteristics as originally specified for the vehicle.