SUMMARY OF SHUDDER THM 440-T4 DIAGNOSIS-POTENTIAL CAUSES

OLDSMOBILE: THIS BULLETIN REPLACES DEALER TECHNICAL BULLETIN 86-T-51. IT CONTAINS REVISED "MODEL" INFORMATION AND TORQUE CONVERTER PART NUMBERS. NOTE: --THIS INFORMATION SUPERCEDES BULLETIN HM 86-25, WHICH SHOULD BE DESTROYED. --THIS BULLETIN SUPPLEMENTS HM 85-17 AND 86-07; CHEVY # 85-34 A VEHICLE EQUIPPED WITH A 1984 THROUGH 1986 THM 440-T4 TRANSAXLE MAY EXPERIENCE A SHUDDER CONDITION WHICH MAY BE DESCRIBED AS SIMILAR TO DRIVING OVER ROUGH PAVEMENT. THIS CONDITION MAY BE THE RESULT OF VARIOUS ENGINE AND/OR TRANSAXLE-RELATED CAUSES. BEFORE DIAGNOSING FOR A TRANSAXLE-RELATED SHUDDER CONDITION, MAKE SURE THE CONDITION IS NOT ENGINE-RELATED. REFER TO THE CHART (FIGURE 2) FOR DIAGNOSIS INFORMATION AND POTENTIAL CAUSES. WHEN PERFORMING ANY SERVICE PROCEDURE, REFER TO THE APPROPRIATE SERVICE MANUAL. REFER TO FIGURE 1 FOR TRANSAXLE IDENTIFICATION. FIGURE 1 PAGE 2, CHART NOTE: A 1986 THM 440-T4 TRANSAXLE BUILT BEFORE MARCH 10, 1986 (JULIAN DATE 069) MAY EXHIBIT A TORQUE CONVERTER CLUTCH APPLY SHUDDER AT 45-55 MPH. THE SHUDDER CONDITION MAY BE CAUSED BY THE DAMPER PLATE NOT FULLY SEATING. IF THE TCC APPLY SHUDDER CONDITION IS EXHIBITED, AND ALL DIAGNOSTIC PROCEDURES HAVE BEEN PERFORMED, REPLACE THE TORQUE CONVERTER WITH A SERVICE CONVERTER AS INDICATED BELOW. MODEL TORQUE CONVERTER PART NUMBER 4CW, 5CM, 5CN, 5CP, 5CW 8656920 5HA, 5HJ, 5HT, 6CFH 6CMH, 6CNH, 6HBH, 6HJH 4BC, 5BA, 5BC, 5BN, 5BR 8656928 6BDH, 6BLH, 6BMH, 6BTH 6BYH, 6BZH 6BBH 8656931 5BS, 5BU, 5BV, 6BHH 8656923 5BW, 5BX, 6BAH, 6BCH, 6BSH 8656930

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.