Immersive virtual reality (VR) has long been considered an excellent environment in which to manipulate 3D virtual objects. However currently used immersive VR user interfaces have limitations. For example, while direct manipulation by hand is easy to understand and to use for approximate positioning, direct manipulation by hand is not suitable for making fine adjustments to virtual objects in an immersive environment because it is difficult to hold an unsupported hand in midair and then to release an object at a fixed point. We therefore propose a method that combines direct 3D manipulation by hand with a virtual 3D gearbox widget that we recently designed. Using this method, hand manipulation is used first to move virtual objects and place them in an approximate position, and then the widget is used to move them into a precise position. The experimental evaluation showed that this combination of direct manipulation by hand and the proposed gearbox is the best of five tested methods in terms of completion ratio of task and subjective preference.