Abstract: A vehicle suspension strut for a vehicle having sprung and unsprung portions, the strut including a telescopic shock absorber including a cylinder and a reciprocable piston and piston rod, attachment means for securing the piston rod to one of the vehicle portions and the cylinder to the other of the vehicle portions, first and second spring seats spaced axially of the strut and spaced radially outwardly from the shock absorber, a helical coil spring arranged substantially concentrically of the shock absorber and extending axially between and supported by the spring seats, means defining a variable volume gas chamber with the shock absorber and including a generally tubular-shaped flexible diaphragm member disposed between the radially outer side of the shock absorber and the radially inner side of the coil spring, one end of the diaphragm member being fixedly secured to the shock absorber cylinder and the opposite end of the member being fixedly secured to the piston rod, and means for supplying pressurized