We report a neutron spin echo (NSE) study of the nanoscale dynamics of the cell–cell adhesion cadherin–catenin complex bound to vinculin. Our measurements and theoretical physics analyses of the NSE data reveal that the dynamics of full-length α-catenin, β-catenin, and vinculin residing in the cadherin–catenin–vinculin complex become activated, involving nanoscale motions in this complex. The cadherin–catenin complex is the central component of the cell–cell adherens junction (AJ) and is fundamental to embryogenesis, tissue wound healing, neuronal plasticity, cancer metastasis, and cardiovascular health and disease. A highly dynamic cadherin–catenin–vinculin complex provides the molecular dynamics basis for the flexibility and elasticity that are necessary for the AJs to function as force transducers. Our theoretical physics analysis provides a way to elucidate these driving nanoscale motions within the complex without requiring large-scale numerical simulations, providing insights not accessible by other techniques. We propose a three-way “motorman” entropic spring model for the dynamic cadherin–catenin–vinculin complex, which allows the complex to function as a flexible and elastic force transducer.