Is there a universal coupling threshold for few-body stability?

We test the hypothesis that a single value of tidal coupling between Keplerian subsystems determines the stability threshold of few-body configurations. We define a standardized measure, the ratio of the tidal acceleration due to the external bodies to the internal acceleration of each subsystem, and compute it at nine simulated thresholds from three families: Lagrange triangles with unequal masses, Maxwell rings, and hierarchical systems. The values range from 0.66% to 5.1%, a spread of about a factor of eight, which refutes the universal constant and preserves an order-of-magnitude rule. Rings with n ≤ 6 are unstable even with coupling well below 1%. We propose that resonance overlap, in the sense of Chirikov, better explains both the common scale and the systematic differences between families.