The shaft outside diameter is $D=114 mm$ and the inside diameter is $d=102 mm$. The polar moment of inertia for the shaft is:

$J=\frac{\pi }{32}[D^4-d^4]$

   $=\frac{\pi }{32}[{\left(114mm\right)}^4-{\left(102mm\right)}^4]$

   $=5,954,575 m{m}^4$