THIS BULLETIN PROVIDES PRODUCTION CHANGE, REPAIR PROCEDURE AND PARTS INFORMATION TO ADDRESS A CUSTOMER CONCERN OF A HIGH-PITCHED SOUND COMING FROM THE TRANSMISSION EXTENSION HOUSING AREA. IN COLD TEMPERATURES, THERMAL CONTRACTION CAUSES SHRINKING OF THE TRANSMISSION CASE. IN HIGH TEMPERATURES, EXPANSION OF THE CASE OCCURS. THESE TEMPERATURE CHANGES AFFECT THE AMOUNT OF PRELOAD ON THE TRANSFER DRIVEN SHAFT BEARINGS. IN SOME RARE CASES, WHEN PRELOAD IS VERY NEAR THE LIMIT OF SPECIFICATION COMBINED WITH UNUSUAL DRIVING CONDITIONS, THIS THERMALLY-INDUCED PRE-LOAD CHANGE MAY CAUSE DAMAGE TO THE BEARINGS AND RESULT IN THE SOUND HEARD BY THE CUSTOMER. A CHANGE HAS BEEN MADE TO THE EXTENSION CASE AND A NEW “DISH PLATE” ADDED. THE MACHINING DEPTH OF THE EXTENSION CASE HAS BEEN INCREASED TO ACCOMMODATE THE NEW DISH PLATE. WHEN USED ALONG WITH A SELECTIVE THRUST WASHER, THE SPRING TENSION OF THE DISH PLATE HELPS TO MAINTAIN A CONSISTENT AMOUNT OF PRE-LOAD ON THESE BEARINGS THROUGHOUT VARYING TEMPERATURE CONDITIONS.
