An improved bearing system is provided for use in high speed rotating machinery such as a turbocharger, wherein a turbocharger shaft is rotatably supported at opposite ends by a pair of angular contact bearings subjected to a predetermined and substantially constant thrust pre-load. The angular contact bearings are carried respectively within a pair of generally cylindrical bearing sleeves which cooperatively define an axially split bearing carrier mounted within a turbocharger housing. A spring reacts between these bearing sleeves for applying a substantially constant axial thrust pre-load transmitted by the bearing sleeves to the angular contact bearings. The mechanical spring thrust pre-load may be supplemented or substituted by an hydraulic axial thrust load attributable to oil circulated through the split bearing carrier.