A/T - Slipping/No Reverse/Repeat Reverse Band Distress
90buick13Bulletin 91-7440-3
Date . Oct. '90
Ref. No. 91-039-7440
Corp. Ref. No. 077130
SUBJECT: NO REVERSE, SLIPPING IN REVERSE AND/OR REPEAT REVERSE BAND DISTRESS (REPLACE TRANSAXLE CASE)
MODELS AFFECTED: ALL 1987-91 MODELS EQUIPPED WITH 4T60 (THM 440T4) TRANSAXLES
BULLETIN COVERS:
A vehicle equipped with a 1987-91 Hydra-Matic 4T60 transaxle may exhibit a condition of no reverse, slipping in reverse and/or repeat reverse band distress. This may be caused by an interference between the reverse band apply bracket and the case. The suspected transaxle cases have an additional wall thickness in the area where the reverse band apply pin engages the apply bracket. The band may never fully apply or release once caught and could cause premature band failure.
Figure 1:
Figure 2:
SERVICE PROCEDURE:
If the transaxle exhibits any of the symptoms discussed in this bulletin, inspect the case die number as shown in Figure 1 and the transaxle Julian Date. If the case die number matches the suspect numbers and the transaxle Julian Date is after the dates listed, disassemble the transaxle and check the case spline number (Figure 2) (located deep inside the barrel of the case next to the right axle seal). If it is listed below, replace the case. If the transaxle is not a suspect unit, then refer to the Automatic Transaxle Diagnosis section of the Service Manual for repair procedures.
LABOR TIME INFORMATION:
Labor Operation: K7800 - Case, Transaxle - Replace
Labor Time: See Chart Below
Vehicle Series
A C E H W
6.5 6.5 6.5 6.5 7.6
SERVICE PARTS INFORMATION:
Part Transaxle
Number Description Model Year Model Usage
8668986 Case, Transaxle 1990 OLAH
8662928 Case, Transaxle 1987-90 All with previous Park
System built before September 25, 1989 (Julian Date 268)
Reference Buick Service Bulletin 90-7440-1 for more information on the new park lock system.
8668985 Case, Transaxle 1990-91 All except OLAH with new
(common case for Park System built after
new park system) September 24, 1989
(Julian Date 267)
Parts are now available from GMSPO.
SERVICE MANUAL REFERENCE:
Refer to the appropriate Service Manual for proper procedures.