Abstract: The present invention provides a radially expandable plateauing tool for finishing bore surfaces. The tool includes a shank for attachment to a means for rotation, and a substantially cylindrical portion including an outer work-engaging surface including abrasive particles secured thereto, and an inner surface defining a bore therethrough with at least one longitudinal split permitting radial expansion and contraction of the cylindrical portion. A metallic spring is disposed within the bore and a threaded bolt assembly or other device is provided for applying an axial compressive force on the spring such that the spring exerts a radial expansive force on the cylindrical portion causing the cylindrical portion to expand to adjust the outer work-engaging surface. The spring is comprised with longitudinal splits aligned with corresponding longitudinal splits on the cylindrical portion to permit coolant flow therethrough.