Brackets for mounting auxiliary suspension systems, such as lift axle systems, to vehicles are disclosed herein. For example, brackets are disclosed for attaching lift axle hanger brackets and lift axle load springs to corresponding frame members. In some embodiments, the frame brackets can include physical features (e.g., a series of graduated steps in an edge portion thereof) to facilitate visual alignment of the lift axle with the vehicle frame members during installation. In other embodiments, the frame brackets can be two-piece brackets that enable the load springs to be removed and replaced without having to detach the frame bracket from the frame rail.