A method for shimming a thrust bearing for an accessory power take off shaft to obtain optimal meshing of bevel gears within the internal gearbox (IGB) without disassembly of the IGB is enabled by relocating the thrust bearing from the engine sump. The accessory gearbox (AGB) is driven from a power off-take from the turbine spool via the IGB. The radial position of the power take-off bevel gear is established by a radial position of the thrust bearing attached to the exterior of the casing via a housing. Candidate shims are selected from a set each having different thicknesses, the shims are formed of two halves and placed between the housing and the engine casing to adjust the radial position of the thrust bearing and consequently the power take-off bevel gear, without requiring the disassembly of the IGB.