the openings at spaced intervals and the selection of the particular location of the bolt nut and washer assembly 6 determines the stiffness or roll rate characteristics of the anti roll bar if assembly 6 is at point 7 the anti roll bar is least stiff i e at the softest position points 8 9 and 10 present intermediate stiffness adjustments with the stiffness of the anti roll bar progressively increasing as the assembly 6 is moved from point 7 to point 8 then to 9 and on to point 10 with assembly 6 point 11 provides the stiffest position in fig1 with the bolt in the 9 position u00bd of the twist resistance of the softer inner member 23 and u00bd of the twist resistance of the stiffer outer spring or member 5 is used with the bolt in the 7 position soft adjustment all of the twisting goes through the softer inner spring member 23 and the outer one member 5 rotates freely at its connected end with the bolt in the 11 position stiffest adjustment the entire length of both members 5 and 23 are constrained to rotate in unison the first embodiment employs a tubular inner torsion member 23 which is welded to or is integrally formed with one of the lever arms here shown in fig5 as part of the left arm 1 each of the left and right lever arms of both embodiments of the invention include a flattened or flange section 30 having but one aperture in this aspect alone the devices of this invention are similar to the prior art nonadjustable anti roll bars of fig2 and 3 the one piece prior art adjustable anti roll bar of fig2.