Celebrity V6-173 2.8L (1989)
Band: Customer Interest
A/T - Harsh Engagement, Double Bump or Shudder
Number:
90-243-7A
Section:
7A
Date:
May 1990 Corp. Bulletin No.: 077119
Subject:
HARSH ENGAGE, DOUBLE BUMP OR SHUDDER-PARK/NEUTRAL TO REVERSE
Model and Year:
1985-90 A CAR AND 1990 W CAR WITH 4T60, F7 (THM 440-T4) AUTOMATIC TRANSMISSICN
THIS BULLETIN CANCELS AND SUPERSEDES DEALER SERVICE BULLETIN NO. 89-29-7A, DATED NOVEMBER 1988. INFORMATION
HAS BEEN ADDED ABOUT THE RUBBER TORSIONAL DAMPER UNIT. ALL COPIES OF 89-29-7A SHOULD BE DISCARDED.
BULLETIN COVERS:
A new reverse band assembly that will help decrease harsh engagement double "bump" or shudder from park or neutral to reverse in a vehicle equipped
with a HYDRA-MATIC 4T60 (THM 440-T4) or THM F-7 transaxle. The new reverse band assembly has new friction material that will help decrease
reverse engagement concerns.
Reverse engagement concerns can be caused by "oxidized" fluid (the fluid may visually appear to be OK), "glazed" (overheated) reverse band assembly
friction material and/or improper surface finish on the drum of the 2nd clutch housing.
IMPORTANT:
Harsh reverse engagement could also be caused by a worn or damaged rubber torsional damper unit (on models so equipped) that is
incorporated as part of of the right hand drive axle shaft. Refer to section 4D of the Service Manual.
SERVICE PROCEDURE:
Check engine idle speed, engine/transaxle mounts, rubber torsional damper unit for the right hand drive axle shaft (on models so equipped) and transaxle
reverse line pressure following Service Manual procedures. If okay, replace the reverse band assembly and 2nd clutch housing drum and bushing
assembly with the appropriate parts listed below in "SERVICE PARTS INFORMATION."
DATE OF PRODUCTION CHANGE:
Starting February 07, 1990 (Julian Date 038) all HYDRA-MATIC 4T60 (THM 440-T4) and THM F-7 transaxles will be built with the new reverse band
assembly.
SERVICE PARTS INFORMATION:
Model
Part
Year
Number
Description
1984-90
8675152
Reverse Band Assembly
1987-90
8661912
2nd Clutch Housing Drum and Bushing Assembly
(six plate)
1984-86
8668958
2nd Clutch Housing Drum and Bushing Assembly
(five plate)
Parts are expected to be available for part number 8675152 on 06-15-90. Until then, normal part orders will not be accepted by GMSPO. Only verifiable
emergency VIP orders will be accepted. SPO will make every effort to obtain parts. All parts will be placed on 400 control to waive VIP surcharges.
However, the part will be shipped premium transportation at dealer's expense. All other order types will be canceled as incorrectly ordered while the 400
control is in place.
Parts are currently available from GMSPO for part numbers 8661912 and 8668958.
SERVICE MANUAL REFERENCE:
Refer to the HYDRA-MATIC 4T60 (THM 440-T4) Automatic Transaxle Unit Repair and OnVehicle sections in the appropriate model year service
manual for repair procedures.
