A/T - 4T60 Slipping/No Reverse
90pontiac20Bulletin Number: 91-7-10
Reference Number: 077130
Publish Date: 9/90
Subject: NO REVERSE, SLIPPING IN REVERSE AND/OR REPEAT REVERSE BAND DISTRESS (REPLACE CASE)
Models
Affected: 1987-91 6000, BONNEVILLE AND GRAND PRIX MODELS W/4T60
BULLETIN COVERS:
A vehicle equipped with a 1987-91 HYDRA-MATIC 4T60 transaxle may exhibit no reverse, slipping in reverse and/or repeat reverse band distress. This may be caused by 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 will distress the fiber liner material across all straps.
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 H W
6.5 6.5 7.6
Case, Transaxle - Replace
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 Pontiac Service Bulletin 90-7-13 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 currently available from GMSPO.
SERVICE MANUAL REFERENCE:
Refer to the appropriate Service Manual for proper procedures.