  We calculate the long-term evolution of angular momentum in double white
dwarf binaries undergoing direct impact accretion over a broad range of
parameter space. We allow the rotation rate of both components to vary, and
account for the exchange of angular momentum between the spins of the white
dwarfs and the orbit, while conserving the total angular momentum. We include
gravitational, tidal, and mass transfer effects in the orbital evolution, and
allow the Roche radius of the donor star to vary with both the stellar mass and
the rotation rate. We examine the long-term stability of these systems,
focusing in particular on those systems that may be progenitors of AM CVn or
Type Ia Supernovae. We find that our analysis yields an increase in the
predicted number of stable systems compared to that in previous studies.
Additionally, we find that by properly accounting for the effects of
asynchronism between the donor and the orbit on the Roche-lobe size, we
eliminate oscillations in the orbital parameters which are found in previous
studies. Removing these oscillations can reduce the peak mass transfer rate in
some systems, keeping them from entering an unstable mass transfer phase.
