Before putting in the axleshaft, the brake rotor should be installed andtorqued in place with all five lug nuts to allow rotor-runout checking.This helps prevent considerable aggravation when the axleshafts areinstalled, since it's difficult to turn the rotor during rotor-runoutchecking. Excessive rotor runout causes brake-fluid aeration and a low,spongy brake pedal. New rotors may need correction due to variations ofthe spindle-rotor mounting surface. Your hardware store should have .005brass shim stock that can be used for rotor-runout correction. Locatethe high spot and place a piece of .005 shim stock on the opposite-sidelow spot between the rotor and spindle.