A torsion isolator (34) for transmitting torque and dampening torsionals in a driveline. The isolator includes a composite c-shaped spring (48) disposed in an annular chamber (44) of a housing (38,40) filled with torque converter fluid. The spring transmits driveline torque and attenuates torsionals. The spring also functions as a fluid displacement piston by dividing the chamber into radially inner and outer volumes (44a,44b) which vary inversely in volume in response to torque changes flexing the spring. Rapid flexing of the spring increases the fluid pressure in the decreasing volume and thereby dampens or reduces the rate of spring flexing or rebound.