A variable turbine geometry turbine turbocharger (1) includes a vane ring assembly (29) configured to control flow of exhaust gas to a turbine wheel (12), and retainers (60, 160) that are used to secure the vane ring assembly (29) to the bearing housing (16) in a desired axial and radial position and angular orientation relative to the bearing housing (16). In some embodiments, the vane ring assembly (29) is spring biased toward an axially outward position relative to the bearing housing (16), and the retainers (60, 160) retain the vane (30) ring in the desired position against the spring bias.