On the nilpotent $\pi$-length of a finite $\pi$-solvable group

New estimates for the nilpotent $\pi$-length of a finite $\pi$-solvable group with the nilpotent commutant of the Hall $\pi$-subgroup are obtained. A connection between the nilpotent $\pi$-length of a finite $\pi$-solvable group and the derivative length of its Hall $\pi$-subgroup of an odd order is established.