An outer combustor wall (36) includes an outer support shell (40) surrounding an outer combustion liner (42). The shell (40) includes a first radial aft flange (46), and the liner (42) includes a second radial aft flange (48) axially adjoining the first flange. An annular retainer (50) and seal (62) are joined to the first flange for slidingly trapping the second flange therebetween for thermally floating the liner on the shell.