  Recent ground--state--focused studies of the tensor effects in the
mean--field framework are our starting point. On the basis of phenomenological
arguments, we indicate regions for acceptable values of the parameters that are
associated with the tensor effective forces within both the Skyrme and the
Gogny models. We identify acceptable signs and values of the parameters by
making an adjustment on the neutron $1f$ spin--orbit splitting for the nuclei
$^{40}$Ca, $^{48}$Ca and $^{56}$Ni. The first nucleus is not used to adjust the
tensor parameters because it is spin--saturated, but is employed to tune the
spin--orbit strength. One of the main conclusions of this work is that some
existing Skyrme parametrizations containing the tensor force should not be
employed because the wrong sign of the tensor parameters does not lead to the
correct behavior (by comparing with the experimental results). This study also
allows us to better constrain the tensor parameters in the Gogny case, where
much less work is published and boundaries and signs for the parameters have
not been analyzed so far.
