shaft 19 as shown in fig3 and 4 fastener 70 may be used to fix the position of adjustment member 60 on arm 56 fastener 70 extends through elongated bore 80 and into coacting threads in arm 56 not shown in addition the fastener head may be disposed within recess 82 to minimize interference with the operation of the suspension as shown in fig5 shaft 19 is disposed inside roller 18 and terminates at a point that is spaced from the vertical wall 32 to form space or gap 90 space 90 permits adjustment of the roller without interference from shaft 19 in an alternate embodiment adjustment member 119 may be an axially positionable shaft that employs coacting threads to adjust the position of the roller with respect to the guide as shown in fig6 roller 18 is axially adjusted by coacting threaded members 110 and 120 the rotation of which changes the axial position of the shaft and attached stop 110 and in turn urges roller 18 towards or away from side wall 38 in yet another alternate embodiment the adjustment member may be comprised of an articulating lever 130 having opposing ends 131 and 133 end 131 engages a fastener 132 and end 133 causes the axial movement of roller 18 as lever 130 pivots about fulcrum or pivot point 134 through the use of fastener 132 end 133 urges roller 18 to either move axially toward or away from guide wall 38 u2014 thus adjusting the roller 39 s position.