IDLER ARM INSPECTION SERVICE PROCEDURE

SUBJECT: INSPECTING C/K TRUCK IDLER ARMS

MODELS: 1988-1992 C/K TRUCKS (12,000 GVW AND BELOW)

Sometimes idler arms on 1988-92 trucks are checked as part of a routine safety inspection or because of a steering complaint. If the vehicle is being inspected for a shimmy complaint first consider areas such as dynamic imbalance, run out or force variation of wheel and tire assemblies and road surface irregularities, etc.

To avoid the customer dissatisfaction involved in replacing idler arms unnecessarily, use the following idler arm checking procedure.

SERVICE PROCEDURE:

1. Raise the vehicle. Support the vehicle with jack stands. Allow the front wheels to rotate freely and the steering mechanism freedom to turn. Position the wheels in a straight ahead position.

2. Place a spring scale and dial indicator near the relay rod end of the idler arm. Exert a 110 N (25 lbs.) force upward and record dial indicator change before and after upward load application. Then exert 110 N (25 lbs.) force downward and record the dial indicator change before and after downward load application. Add the two deflections due to the upward and downward load, the total allowable deflection is 6.4 mm (1/4-inch). Replace the idler arm if the deflection exceeds this amount.

Important

Moving the front wheel and tire assemblies back and forth, causing an up and down movement of the idler arm, is NOT an acceptable testing procedure. There is no control on the amount of force being applied to the idler arm.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.