A totally split mechanical face seal being installable and replaceable without necessitating breakdown of the shaft and/or housing. The inventive split seal is well suited for replacement of packing or stuffing in heavy duty or inaccessible locations. The inventive seals include a sealing element that seals the primary ring against the shaft and rigidly positions the primary ring in the axial, circumferential and radial directions, and also includes a sealing element which seals the mating ring against the housing and non-rigidly positions the mating ring in the axial direction while simultaneously providing an axial biasing force on the mating ring to provide mating contact of the two rings. For applications where gross displacements of the shaft relative to the housing are expected, a thrust bearing or a connection is made between the mating ring assembly and rotating elements associated with shaft. Alternatively, a bearing assembly is provided for maintaining the axial position of the primary ring assembly and both primary and mating rings are held in approximately the same positions relative to each other regardless of the gross shaft displacements.