We present an experimental study of erosion of the dayside magnetosphere, utilizing solar wind measurements from the Wind spacecraft and magnetic field measurements from the Goes spacecraft when located between 11.00-13.00 MLT. We focus on three case studies encompassing 3 levels of solar wind dynamic pressure and 3 levels of moderate, negative IMF B_z. In all cases the variation of B_z and dynamic pressure do not exceed 1 nT and 1 nPa, respectively. The AL index is analyzed to confirm that the day-side observations refer to the substorm growth phase. Particular attention is thus paid to the timing of sub-storms to infer the delay times for onset signatures to reach the dayside.