A split mechanical end face seal assembly has a split gland plate assembly, a split mating seal ring assembly, a split primary seal ring assembly and a split biasing assembly. The segmented mating seal ring is axially and radially supported on the segmented mating ring adapter by resilient connector strips as pre-assembled sub-assemblies and the resilient connector strips axially non-rigidly support the mating seal ring within said mating ring adapter assembly. An axially movable primary sealing ring assembly includes a segmented primary seal ring. The biasing assembly is pre-assembled into the gland plate assembly and urges the primary seal ring into sealing relation with the mating seal ring. A method of installation includes resilient axial and radial support of the mating seal ring segments in mating ring adapter segments by the resilient connector strip for installation as a pre-assembled sub-assembly. It further includes pre-assembly of semi-circular shaped biasing ring segments into segments of the gland plate assembly.