BEARING NOISE IN PARK/NEUTRAL DRIVE SPROCKET THM 125-C

SOME 1982 AND 1983 THM 125C TRANSMISSIONS MAY EXPERIENCE A NOISE CONDITION, BEST DESCRIBED AS A HIGH PITCHED WHINE. THIS NOISE CONDITION, IF ONLY NOTICEABLE IN PARK AND NUETRAL AND NOT IN DRIVE OR REVERSE (WHILE STOPPED WITH BRAKES APPLIED), COULD BE CAUSED FROM ONE OR MORE OF THE FOLLOWING BEARINGS. 1. DRIVE SPROCKET ROLLER CAGE BEARING 2. DRIVEN SPROCKET ROLLER CAGE BEARING 3. DRIVEN SPROCKET THRUST BEARING (ILLUSTRATION) WHEN SERVICING ANY 1982 OR 1983 THM 125C FOR THIS BEARING NOISE, FIRST INSPECT THE DRIVE AND DRIVEN SPROCKET ROLLER CAGE BEARINGS AND DRIVEN SPROCKET THRUST BEARING FOR WEAR OR DAMAGE. IF WEAR OR DAMAGE IS VISABLE ON ANY OF THE ABOVE BEARINGS, REPLACE THEM WITH SERVICE PARTS LISTED BELOW: 1. DRIVE SPROCKET ROLLER CAGE BEARING - 8631186 2. DRIVEN SPROCKET ROLLER CAGE BEARING - 8631190 3. DRIVE SPROCKET THRUST BEARING - 9436851 REFER TO YOUR SERVICE MANUAL FOR REMOVAL AND INSTALLATION PROCEDURES OF THE DRIVE AND DRIVEN SPROCKET SUPPORT CAGE BEARINGS. SECOND BULLETIN: THIS BULLETIN PROVIDES ADDITIONAL INFORMATION ON A NOISE CONDITION ON SOME 1982 AND 1983 THM 125-C TRANSMISSIONS. THIS NOISE CONDITION COULD ALSO BE CAUSED BY A ROUGH SURFACE ON THE DRIVEN SPROCKET (FIGURE #1, ITEM #122), WHERE THE DRIVEN SPROCKET ROLLER CAGE BEARING LOCATES. WHEN SERVICING A 1982 OR 1983 THM 125-C FOR THIS NOISE CONDITION, INSPECT THE DRIVEN SPROCKET, FACE, WHERE THE ROLLER BEARING LOCATES, FOR A ROUGH OR WORN SURFACE. IF THE DRIVEN SPROCKET SHOWS SIGNS OF ROUGHNESS ON THE BEARING SURFACE, IT MUST BE REPLACED.

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.