Most of the published studies on gear dynamics focused either gear durability or noise and vibration. Dynamic tooth forces and dynamic stress factors were the main concern of the durability related work while the dynamic motion transmission error and gearbox vibrations were investigated for noise purposes. Two recent theoretical studies by Tamminana et al. 1 and Velex and Ajmi 2 provided formulations to define certain relationships between the dynamic or quasi-static motion transmission error and dynamic tooth forces or dynamic factor of spur gears in an attempt to bridge these two groups of studies. This paper provides a comprehensive set of experimental data consisting of both dynamic stress factor and dynamic transmission error values collected simultaneously from the same gears to complement these earlier theoretical studies in terms of the relationship between durability and noise metrics. A gear dynamics test set-up with integrated root strain and dynamic transmission error measurement systems is described. Dynamic factor and dynamic transmission error measurements from unmodified and modified spur gears are presented and their relationship is demonstrated experimentally. •Experimental setup for dynamic stress and transmission error factor measurements.•Simultaneous measurements of DF and DTE were conducted.•Effect of backlash nonlinearity on DF and DTE is demonstrated experimentally.•Impact of tooth modification on DF and DTE is investigated through measurements.•Empirical linear correlation between DF and DTE is given.