A vehicle seat of the type having a seat back with a plurality of transverse serpentine springs therein is provided with a regulating apparatus for adjusting the firmness of the lowermost springs to adjust the firmness of the seat back in the lumbar region. A torsion spring is wrapped about a vertically extending post in the lower corner of the seat back with one end thereof operatively engaged with the seat spring adjacent the lower center portion of the seat back and the opposite end being secured to a nut threaded on a rotatable shaft so that rotation of the shaft will vary the force of the torsion spring on the seat spring.
