This study is focusing on the distortion phenomenon of the vibrational resonance peak when testing an e-drive assembly via RPM-sweep excitation. As the ramp rate increases, the measured response function deviates more and more from the stationary response. This distortion leads to a reduced peak amplitude, a shift in resonant frequency, changes in response shape and consequently, results in an increased half-power bandwidth, eventuating an increased apparent modal damping. These changes in the response are dependent on the sweeping direction and other physical parameters as well, like oil pressure and -temperature. The phenomenon was investigated earlier for linear systems, but not for operational testing of rotary machines, where the characteristics of the spectrum distortion are governed by different principles and are influenced by many other physical factors. A novel way for handling amplitude distortion of e-drives during transient testing is elaborated, which can be used to optimize RPM-sweep rate and other measurement parameters.