Abstract: Apparatus for measuring rotational imbalance of a turbocharger core assembly, comprising a base frame (30) having a housing (31) in the form of an exhaust duct. Attached by leaf springs (33) to the housing (31) is a support part (35) and a co-axial adaptor (36) to which a turbocharger core assembly (38) is removably attached by quick-release clamps (37). An air inlet (40) receives air to drive the turbocharger core assembly via a volute within the adaptor (36), and any imbalance of the turbocharger core assembly, causing oscillatory vibration via the leaf springs (33) is measured by an accelerometer (40) mounted on the support part (35).