A/T - Intermittent Loss of Drive
89chevy32Number: 90-17-7A
Section: 7A
Date: June 1989
Subject: INTERMITTENT LOSS OF DRIVE
Model and Year: 1984-90 A, W CAR WITH 440-T4 TRANSMISSION
Figure 1 - THM 440-T4/THM F-7 Transaxle Identification Information:
TO: ALL CHEVROLET DEALERS
A vehicle equipped with a THM 440-T4/HYDRA-MATIC 4T60 (Figure 1) transaxle may experience an intermittent loss of Drive. This may be caused by the 1-2 band stop (139) being below specification allowing the band to shift off location causing the 1-2 Band Apply Pin to miss the Band while stroking, creating a loss of drive. The vehicle will still have Reverse gear. If there is no Forward and Reverse gear, then it is most likely a damaged input clutch sprag assembly.
Figure 2 - Removal Of Bottom Case Components:
SERVICE PROCEDURES: (Figures 2-6)
The 1-2 band stop (139) can be replaced while the transaxle is in the vehicle by removing the screws (60), transmission oil pan (59) and oil filter assembly (58) as listed in the Service Manual, then:
Figure 3 - Removing Old 1-2 Band Stop:
1. Using a punch and hammer, tap the black plastic adjusting tab into the 1-2 Band stop assembly just enough so the stop can be removed with pliers (Figure 3).
Figure 4 - Using 1-2 Band Stop Installation Tool:
2. Use J 38229 1-2 band stop installation tool as shown in Figure 4 by first putting the 1-2 band stop into the tool then put the stop into the hole and while pushing on the base, squeeze the handle of the tool to its preset stop.
Figure 5 - Cutting Off Tab:
3. Cut off the remaining adjusting tab as shown in Figure 5.
Figure 6 - 1-2 Band Stop:
IMPORTANT: The 1-2 band stop height can be checked during an overhaul. With the transaxle disassembled the 1-2 band stop must protrude 14 mm (9/16") through the case as shown in Figure 6.
SERVICE TOOL INFORMATION:
The 1-2 Band Stop Installation Tool J 38229 will be available later in the 1989 calendar year from Kent-Moore. Order the tool from Kent-Moore's order department at (313) 574- 2332 or 1-800-345-2233.
SERVICE PARTS INFORMATION:
Service Package Contents Application
8649302 Stop, 1-2 Band Assembly 1984-1990 model years
Parts are currently available from GMSPO.
SERVICE MANUAL REFERENCE:
Refer to the appropriate model year THM 440-T4/HYDRA-MATIC 4T60 (ME9) On-Car Service and/or Automatic Transaxle Unit Repair Table of Contents for Case Assembly that will contain the 1-2 band stop service information.
For Warranty Repairs use:
1-2 Band Stop - R&R Labor Operation
T5185
Labor Time .6 Hour