PIAGGIO 633929(IT) Service Station Manual page 180

Suspensions
Remove the constant-velocity universal joint from
the steering bar by undoing the nut indicated in the
photograph.
Use a specific tool to remove the upper tightening
ring nut of the steering tube.
Specific tooling
020055Y Wrench for steering tube ring nut
Remove the hydraulic pipe support bracket.
SUSP - 8
MP3 125