The spin and orbital evolution for our W-R–BH binaries. All systems have equal mass companions initially. The solid and dashed lines show the spin and orbital frequencies, respectively. Line colors indicate the evolving central helium mass fraction. The stars mark the end of evolution (core helium depletion), and the red “ZF” symbols show the spins if Zahn’s formalism (Equation (6) in the published article) is assumed. Left: systems with initial orbital periods of 0.3 days and a mass-loss rate equivalent to solar metallicity. Mass loss is very significant for high-mass models and the final spins depart from Zahn’s formalism for them. Middle: systems with initial orbital periods of 0.8 days and a mass-loss rate equivalent to solar metallicity. Mass loss overpowers tidal spin-up and the primaries are not spun up much, consistent with Zahn’s results. Right: systems with initial orbital periods of 0.3 days and a mass-loss rate equivalent to 0.01 solar metallicity. Mass loss is negligible for most systems and the primaries are partially spun up, but not as much as Zahn’s formalism predicts. None of these models reach tidal synchronization.