A turbocharger having a variable-nozzle turbine, comprising: a turbine assembly comprising a turbine housing and a turbine wheel mounted in the turbine housing and connected to a rotatable shaft for rotation therewith, the turbine housing defining a chamber surrounding the turbine wheel for receiving exhaust gas from an engine and for supplying the exhaust gas to the turbine wheel, the turbine assembly defining a nozzle leading from the chamber generally radially inwardly to the turbine wheel; a compressor assembly comprising a compressor housing and a compressor wheel mounted in the compressor housing and connected to the rotatable shaft for rotation therewith; a center housing connected between the compressor housing and the turbine housing, the center housing having a radially outwardly facing surface and an axially facing surface that faces toward the turbine assembly; a generally annular nozzle ring and an array of vanes circumferentially spaced about the nozzle ring and disposed in the nozzle such that exhaust gas flows between the vanes to the turbine wheel, the vanes being rotatably mounted to the nozzle ring such that the vanes are rotatably adjustable for regulating exhaust gas flow to the turbine wheel, wherein the nozzle ring includes a radially inwardly facing surface; and a spring sleeve of generally S-shaped cross-section having resilience in the radial direction when compressed radially and resilience in the axial direction when compressed axially, the spring sleeve being disposed between the radially inwardly facing surface of the nozzle ring and the radially outwardly facing surface of the center housing, the spring sleeve being radially compressed between the respective radially facing surfaces (444, 421) of the nozzle ring and the center housing so as to radially center the nozzle ring relative to the center housing. a turbine assembly comprising a turbine housing and a turbine wheel mounted in the turbine housing and connected to a rotatable shaft for rotation therewith, the turbine housing defining a chamber surrounding the turbine wheel for receiving exhaust gas from an engine and for supplying the exhaust gas to the turbine wheel, the turbine assembly defining a nozzle leading from the chamber generally radially inwardly to the turbine wheel; a compressor assembly comprising a compressor housing and a compressor wheel mounted in the compressor housing and connected to the rotatable shaft for rotation therewith; a center housing connected between the compressor housing and the turbine housing, the center housing having a radially outwardly facing surface and an axially facing surface that faces toward the turbine assembly; a generally annular nozzle ring and an array of vanes circumferentially spaced about the nozzle ring and disposed in the nozzle such that exhaust gas flows between the vanes to the turbine wheel, the vanes being rotatably mounted to the nozzle ring such that the vanes are rotatably adjustable for regulating exhaust gas flow to the turbine wheel, wherein the nozzle ring includes a radially inwardly facing surface; and a spring sleeve of generally S-shaped cross-section having resilience in the radial direction when compressed radially and resilience in the axial direction when compressed axially, the spring sleeve being disposed between the radially inwardly facing surface of the nozzle ring and the radially outwardly facing surface of the center housing, the spring sleeve being radially compressed between the respective radially facing surfaces (444, 421) of the nozzle ring and the center housing so as to radially center the nozzle ring relative to the center housing.