INTERMITTENT LOSS OF DRIVE CHECK 1-2 BAND STOP

A,C,H,E,K,V, & W CARS

Bulletin Covers:(Figure 1)

A vehicle equipped with a THM 440-T4/HYDRA-MATIC 4T60 or THM F-7 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 a damaged input clutch sprag assembly is likely.

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:

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).

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 till its preset stop.

3. Cut off the remaining adjusting tab as shown in Figure 5.

IMPORTANT: The 1-2 band stop height can be checked during an overhaul. With the transaxle disassembled the 1-2 band stop must protrude 14mm (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

SERVICE MANUAL REFERENCE:

Refer to the appropriate model year THM 440-T4/HYDRA-MATIC 4T60 (ME9) or THM F-7 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.

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.