The impact of full convection on stellar dynamos remains an open problem. Recent work has reported an abrupt shift in both rotation and braking torque across the fully convective boundary, suggesting a plausible association with changes in the magnetic field. We examine this transition region with 320 K/M dwarfs within wide (>100 au) binary systems, leveraging the companion white dwarfs’ cooling ages for age determination of these systems. Using a calibrated magnetic braking law, along with assumptions about initial conditions and angular momentum transport, we construct gyrochrones to predict the rotation periods of the main-sequence (MS) stars. Both data and models show that, near the fully convective boundary, MS stars with ages up to 7.5 Gyr experience a rotation period increase by up to a factor of ≈3 within a < 50 K effective temperature range. The rapid braking at this boundary is ubiquitous across models and is driven by a sharp rise in the convective overturn timescale due to structural changes between partially and fully convective stars caused by the 3He instability near the fully convective boundary. Hence, invoking a modification to the stellar dynamo mechanism is not necessary to explain stronger magnetic braking at the fully convective boundary; changes in the torque naturally result from changes in the stellar structure. Stars on this spike show a Rossby number that is 0.2 − 0.7 lower than stars on either side of this feature, depending on the age, corresponding to a ∼ 2 − 20 times enhancement in activity, assuming magnetic activity scales as Ro^(−2). This represents a relatively subtle change compared to the one-order-of-magnitude spread in X-ray luminosities from observational Lx/Lbol−Ro relations, allowing such a feature to escape previous detection.