I am a Renault Technical Expert (RTE)
I have come accross same problems as everybody else where the harmonic dampers are separating from the Viscous coupling on the prop shaft, if the coupling is damaged these are available from
They say that you can remove the harmonic dampers and will have minimal vibration.
Providing that the rubbers in the dampers arnt to bad and the dampers are still in the correct position I have repaired a few of these using windscreen bonding this rebonds the rubber and creates a flexible take up for the dampers when setting off from start this method has proved to have been a susessfull repair in the past and see vehicles coming back year after year with the repair still intact.
hope this tip for the repair will help anybody with the dreaded Scenic 4X4 harmonic dampers separating