Method and system to coat an expandable member of a medical device comprising a support structure to support the expandable member and an applicator positioned with at least one outlet proximate a surface of an expandable member. A drive assembly establishes relative movement between the at least one outlet and the surface of the expandable member to apply fluid on the surface of the expandable member along a coating path. A tracking mechanism maintains a substantially fixed distance between the at least one outlet and the surface of the expandable member during relative movement therebetween by displacing the at least one outlet relative to the expandable member.