WHINE AT HIGHWAY SPEEDS NEW DESIGN SPEEDO CABLE

VEHICLES AFFECTED: 1985-86 'S' Car With Automatic Transmission

Some of the subject vehicles may exhibit a high pitched whine at highway speeds. This condition occurs in any gear and is most apparent during acceleration and coast down maneuvers at these speeds.

The condition is caused by the constant mesh counter gear set located at the extreme outboard end (left hand side of car) of the transmission. This noise is transferred through the speedometer cable into the passenger compartment. This noise does not indicate a reliability or durability concern with regard to the transmission.

A new speedometer cable design incorporating a sound isolation feature has been released, this is a two-piece cable design and is available from GM Parts by ordering both parts: 94844466 speedometer cable-lower; 94844467 speedometer cable-upper.

NOTICE: BOTH PARTS ARE REQUIRED TO REPLACE THE EXISTING ONE-PIECE CABLE.

Revised counter gear tooth geometry has also been developed to reduce gear noise, a kit is available from GM Parts by ordering P/N 94844514.

Both of the above design changes are incorporated in vehicles produced after VIN serial number (last 6 digits) 190000 for USA and 253500 (Canada) during the 1986 model year (date Code G).

To correct this condition on complaint vehicles built prior to these VIN breakpoints the following steps should be carried out:

1. To Remove existing one-piece speedometer cable, See Illustration and instructions for procedure.

2. Install new upper and lower cables after first connecting the two parts together at the connector. The connected speedo cables can be installed by reversing the procedures for removing the original cable.

3. Evaluate vehicle for existence of complaint condition and compare with original complaint level. If a satisfactory level of improvement has been achieved, no further changes are required.

NOTICE: TESTING HAS SHOWN THAT THE TWO-PIECE SPEEDO CABLE WILL SATISFACTORILY CORRECT THE MAJORITY OF COMPLAINT VEHICLES. IN THE EVENT THAT A SATISFACTORILY LEVEL OF PERFORMANCE HAS NOT BEEN REACHED, PROCEED TO STEP 4.

4. Replace counter-gear with parts contained in new counter-gear kit using existing Shop Manual procedures.

Use applicable Labour Time and Operation Number.

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.