If I remember correctly, the service manual says to torque spindle nut to 12 lb/ft while spinning rotor forwards. Back off half a turn, then tighten to 12 lb/ft. Insert cotter pin (backing off nut if necessary).
What I usually do is tighten the nut until there is some resistance on the rotor, spin the rotor a few times, back off the nut and just hand tighten with a socket then install cotter pin. What you are really trying to do here is squeeze the grease out of the bearings to create a tight tolerance between the rollers & races. Make sure the rotor spins freely when finished.