you are supposed to set the pre-load with a knuckle pull scale to get the proper amount of shims.... every time I have done mine I just use the shims that came out and make sure the pre-load feels ok and all is good and tight! the amount of shims will not affect how your wheels are sitting... chances are the leaks are caused by bad inner axle seals... order the marlin HD seals and never go back the stock ones will always leak!