  The $1/N_c$ rotational corrections to the axial vector constant and the
isovector magnetic moment of the nucleon are studied in the Nambu --
Jona-Lasinio model. We follow a semiclassical quantization procedure in terms
of path integrals in which we can include perturbatively corrections in powers
of angular velocity $\Omega \sim \frac 1{N_c}$. We find non-zero $1/N_c$ order
corrections from both the valence and the Dirac sea quarks. These corrections
are large enough to resolve the long-standing problem of a strong
underestimation of both $g_A$ and $\mu^{IV}$ in the leading order. The axial
constant $g_A$ is well reproduced, whereas the isovector magnetic moment
$\mu^{IV}$ is still underestimated by 25 \%.
