Important: 
   •  Do not jerk the right tire and wheel assembly back and forth, causing
an up-and-down movement of the idler arm. This is not an acceptable testing
procedure because there is no control on the amount of force being applied
to the idler arm.    •  Use care whenever loose idler arms are suspected of causing shimmy complaints.
Before suspecting suspension or steering components, consider the following
areas:       -  Dynamic imbalance       -  Runout       -  Force variation of tire and wheel assemblies       -  Road surface irregularities 
The allowable deflection is 3.18 mm (1/8 in) from the center for a total of 6.35 mm (¼ in) (1).