If you own a Jeep with a leaf spring suspension system, you probably know a thing or two about shackles. Because the leaf spring is mounted solidly on one end, it must have a part that allows for movement and adjusts to changing road conditions on the other end. Located between the frame and the spring, this part is called a shackle. When off-roading enthusiasts make modifications to their tires, wheels, and suspension systems, they must also change shackle lengths. Failure to do so could adversely affect driving performance and lead to premature wear on vital parts and components. Longer shackles on your Jeep Wrangler also add lift to the suspension system, which is necessary for just about any off-roading activity.