into an elastomer material 58 namely two outer half bushings of the same diameter 52 54 and an inner half bushing of smaller diameter 56 in a radial plane the elastomer material 58 has a generally v shaped cross section the inner half bushing 56 being located at the base of this v and the two outer half bushings 52 54 being located at the ends of the branches of this v the groove 32 is thus determined between the two branches of the v constituted of elastomer material capable of compression under the stress of transverse vibration of the stay 6 as is shown by the upper part of fig2 and the partial stripping of the elastomer material 58 in fig4 the metal half bushings 52 54 56 each have over most of their perimeter a rectangular shaped cross section to allow the assembly of the two halves 50 the half bushings 53 54 56 each have their two ends 62 64 66 which protrude from the moulded elastomer material 58 one end 62 64 66 of each half bushing 52 54 56 is in the shape of a clevis provided with a pinning aperture 72 74 76 whereas the other end 63 65 67 has a complementary shape of the clevis and is provided with a corresponding pinning aperture 73 75 77 the pinning apertures 72 77 allow the assembly of the two ring halves 50 by means of three pairs of pins 82 84 86 extending parallel to the direction of the stay section 6 see the lower part of fig2 a ring half 50 is easily manufactured by injecting the elastomer material 58 into an appropriately shaped mould in which have previously been placed the three half.