.... hmmm ...........
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noise=too late
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if you have an issue with a bearing .... due to insufficient grease ........ it will probably be too late by the time you are aware of it due to an audible sound .........
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there may not be any sound/noise to warn you ...... ??? ..... maybe *after* the bearings have become 'welded' to the spindle ........... and/or the spindle is in the process of being cut in half .......

the rotors are not the only item you are 'saving' when you repack the front bearings ....... the spindles ....... bearings ........ etc .......