typically when used in automobile suspension the leaf both supports an axle and locates/ partially locates the axle. this can lead to handling issues (such as 'axle tramp'), as the flexible nature of the spring makes precise control of the unsprung mass of the axle difficult. some suspension designs use a watts link (or a panhard rod) and radius arms to locate the axle and do not have this drawback. such designs can use softer springs, resulting in better ride. the various austin-healey 3000's and fiat 128's rear suspension are examples.