A system that is capable of monitoring tribological data, such as friction, in a data storage device. In accordance with various embodiments, a magnetoresistive head is separated from a rotating data storage media by an air bearing and attached to a slider that is adjusted through deformation controlled by a heating element. A measurement circuit concurrently monitors friction from the head and power applied to the heating element to determine an MR head clearance. The measurement circuit includes at least a phase filter that eliminates off-phase friction from contributing to the determination of the MR head clearance.