......after you separate front rotors from hubs, use a mill file, razor blade scraper and emery cloth to make sure that the mating surface on the hub is perfectly clean and FLAT..you dont want to distort the new rotors. Cover bearing hole when you do this so you dont get any crap in with the bearings. Also use high temp. lock-tite on bolts when you install new rotors.

Since this is the time to clean and re-pack bearings (assuming yours are good), put on a new set of grease seals.

Good Luck

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1984 300TD Wagon, 407,800 mi (current daily driver)
1985 300DT Sedan, 330,000 mi (gone to that great autobahn in the sky)