Thermal effects influence film thickness and friction, particularly in lubricated non-conformal contacts at high values of rolling and sliding velocities. Some effects depend on the lubricated contact itself, but some others are related to the surrounding conditions. In this paper, an experimental work is presented, where three spherical specimens with different diameters are tested against a disc under the same working conditions. Tests are carried out with the specimens connected to two different rotating shafts: a steel shaft and a shaft with a ceramic insert purposely designed for limiting the heat transfer to the specimens. The friction values and trends, as well as the measured temperatures in different points of shafts and specimens, show a not negligible influence of the set-up of the experimental apparatus on the results.