A hydroelastic support assembly comprises a frusto-conically shaped rubber support (10) connected to a vehicle engine by an upstanding stud (12) and connected to the vehicle body by a metal platform (14). The hollow interior of the rubber support (10) defines a main hydraulic chamber (22) which is open to a damping cassette (24) via an aperture (18) in the platform (14). The cassette (24) comprises a compensation chamber (30) having a flexible wall (28) and which is connected to the main hydraulic chamber (22) via a restricted annular canal (32) to provide hydraulic damping. A flexible membrane (40) provides damping of low amplitude vibrations. The cassette (24) is made substantially completely of thermoplastic or composite material and is thus relatively inexpensive and light in weight. It is secured in the assembly by means of structural adhesive (46) and held in position while the adhesive sets by clips (47). <IMAGE>
