Ifound a trick to keep grease from contaminating the brakes. You just cut the end of the axles greasing caps with a quarter of an inch slit with a pointed exacto blade. and clean the inside of these ;rubber caps so that the slight pressure developped with a change of temperature either from the weather or from the heath of rolling will escape by the slit instead of by the grease seal.
but keep the insside surface of the caps clean otherwise the grease will block the slot. If you doubt my idea, just try it on a wheel that gave you problems...worked for me good luck. The dust wont get in cause the lips of the slot keep tight close when no inside presure.