A leaf spring is a type of suspension system that uses stacked metal leaves to absorb shock. These leaves are attached to a leaf spring shackle at the frame and then to the axle. Leaf spring U-bolts attach the axle and leaf spring together. The U-bolt wraps around the axle and attaches to the leaf spring using a plate. They come in both round and square types. Some leaf springs are located below the axle; when this is the case, a round leaf spring U-bolt is needed. The U-bolt wraps around the axle and attaches to the leaf spring using a plate. If you notice increased shakiness or noise beneath your vehicle, check your leaf spring and leaf spring U-bolt. If you need a leaf spring, leaf spring shackle, or leaf spring U-bolts, check out O'Reilly Auto Parts and check out our selection of parts for your car, truck, or SUV.