NEW PRODUCT INFORMATION 1989 THM 440-T4, F7 (ME9)

Models Affected: 1989 6000, BONNEVILLE, AND GRAND PRIX

BULLETIN COVERS:

New Product Information on all 1989 model THM 440-T4 transaxles. The information contained in this bulletin describes changes that occurred at the Start Of Production (SOP) for 1989 THM 440-T4 transaxles. Refer to each section of this bulletin for specific product change informa- tion.

DATE OF PRODUCTION CHANGE: (Figure 1) ------------------------- At the Start of Production, 1989 THM 440-T4 transaxles were produced with the product changes listed in this bulletin.

SERVICE MANUAL REFERENCE:

Refer to the Transaxle Hydraulic Diagnosis and Transaxle Unit Repair Sections in your 1989 Service Manual for changes shown in this bulletin.

SUBJECT: -------- NEW REVERSE SERVO APPLY PIN SELECTION CHART

CHANGE TO ASSEMBLY COMPONENT: (Figure 2) ---------------------------- The reverse servo apply pin (551) selection chart has been changed for the 1989 model year to eliminate the longest and the two shortest of the selection set. The 1989 transaxle calibrations require a new selection set for the THM 440-T4 Transaxles.

SERVICE ACTION:

When servicing a past model THM 440-T4 transaxle use the proper year servo apply pin selection chart.

SERVICE PARTS INFORMATION:

Reference new reverse servo apply pin selection chart, Figure 2.

SERVICE MANUAL REFERENCE:

This product change informaiton is shown in the THM 440-T4 Automatic Transaxle Unit Repair section of your 1989 Service Manual.

SUBJECT: ------- 10 PLATE 3rd CLUTCH PACK

CHANGE TO ASSEMBLY COMPONENT: (Figures 3, 4, 5, 6, 7, 8 and 9) ---------------------------- A new 10 plate 3rd clutch pack (640) is used to replace the 8 plate 3rd clutch pack for all 1989 THM 440-T4 transaxles. The two extra plates were added for new higher torque engine applications. For this change to be implemented the following parts were modified:

- 3rd clutch plate (fiber one side) I.D. and O.D. splines, (Figure 4) are thinner by 0.15mm (0.006"). The fiber material is the same thickness only the steel part of the plate was made thinner.

- Input clutch piston (630) cutouts for the 3rd clutch plates are 6.35mm (0.25") deeper so the piston travel will clear the increased thickness of the 3rd clutch plate pack. (Figure 5)

- 3rd clutch piston housing (633) has decreased in overall size. (Figure 6)

- 3rd clutch piston (637) seal (635) is now molded to the piston (802) (Figure 7).

- 3rd roller clutch outer race (645) is wider by 0.83mm (0.033") to accommodate the two extra plates. (Figure 8) Note: The rollers have not changed in width.

- 3rd clutch spring retainer and guide assembly (638) cutout is 1.1mm (0.043") deeper for 1989. This allows sufficient clearance for the relocated retainer and ball assembly that is part of the new 3rd clutch piston seal assembly and retainer and ball assembly (802). (Figure 9)

SERVICE ACTION:

When servicing a 1984 through 1988 THM 440-T4 transaxle you must use the previous 3rd clutch pack assembly as shown in the Service Parts Information section below. DO NOT interchange individual components with previous model years or a misbuild will occur. The 1989 input clutch apply piston assembly (630) and 1989 3rd clutch spring retainer and guide assembly (638) are the only components of the 10 plate 3rd clutch pack that can service prior model years.

SERVICE PARTS INFORMATION:

Part Model Model Number Description Year Usage ------ ----------- ---- ----- 8662927 Plates, 3rd Clutch (fiber 1988 8AAH, 8ABH, 8AFH, one side with wave plate) 8AJH, 8ANH, 8ATH, (8 plates) (640) 8CFH, 8CMH, 8GRH, 8CTH, 8CWH, 8CXH

8646938 Plates, 3rd Clutch (fiber 1987-88 All 87 Models, one side) (8 plates) (640) 8BJH, 8BKH, 8BRH, 8BTH, 8BYH, 8FBH, 8FCH, 8FJH, 8FSH, 8VXH

8662954 Plates, 3rd Clutch (fiber 1989 All Models one side with wave plate) (10 plates) (640)

8668295 Piston Asm. Input Clutch 1984-89 All Models Apply (630)

8656310 Housing, 3rd Clutch 1984-88 All Models Piston (633)

8668359 Housing, 3rd Clutch 1989 All Models Piston (633)

8644919 Piston, 3rd Clutch (637) 1984-88 All Models

8668453 Seal Asm. and Retainer and 1989 All Models Ball Asm., 3rd Clutch Piston (802)

8662676 Roller Asm. Comp. - 3rd 1984-88 All Models Clutch (645)

8668367 Roller Asm. Comp. - 3rd 1989 All Models Clutch (645)

8662674 Spring Retainer and Guide 1984-88 All Models Asm. - 3rd Clutch

8668071 Spring Retainer and Guide 1984-89 All Models Asm. - 3rd Clutch

All parts listed above, except part number 8668295, are currently available from GMSPO.

Part number 8668295 is expected to be available on October 24, 1988. Until then normal part orders will not be accepted by GMSPO. Only verifiable emergency VIP orders will be accepted. GMSPO 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 cancelled as incorrectly ordered while the 400 control is in place.

SERVICE MANUAL REFERENCE:

This product change information is shown in the THM 440-T4 Automatic Transaxle Unit Repair section of your 1989 Service Manual.

SERVICE NOTES:

The 3rd clutch wave plate (800) (was 640A for 1988) is standard on all 1989 vehicles equipped with a THm 440-T4. The wave plate (640A) for 1988 was only used on vehicles equipped with 2.8L engines.

SUBJECT: ------- ONE PIECE CHANNEL PLATE GASKET

CHANGE TO ASSEMBLY COMPONENTS: (Figure 10) ----------------------------- A new one piece channel plate (upper) gasket (801) is used to replace the channel plate (upper) gasket (409) and modulator port gasket (415) . The one piece design ensures that the gasket does not become misposi- tioned upon assembly of the channel plate.

SERVICE ACTION:

When servicing a past model (built after 1985-1/2) use the new one piece channel plate (upper) gasket. The one piece channel plate (upper) gasket will service all past models back to 1985-1/2. Transaxles built before 1985-1/2 must still use the two piece channel plate gasket. Important

The new one piece channel plate gasket cannot be used to service transaxles built before Julian Date Oll for 1985 models. If the new gasket is used on a previous channel plate, park, reverse and neutral (PRN) fluid may enter the reverse servo feed circuit and apply the reverse band. Since the input clutch is applied in Park, the transaxle may be in Park and Reverse at the same time when Park is selected.

SERVICE PARTS INFORMATION:

Part Model Model Number Description Year Usage ------ ----------- ---- ------ 8646945 Gasket, Channel Plate 1985 1/2-89 All (one piece upper/lower)

8646908 Gasket, Channel Plate 1984-85 1/2 All (two piece upper/lower)

Parts are currently available from GMSPO.

SERVICE MANUAL REFERENCE:

This product change information is shown in the THM 440-T4 Automatic Transaxle Unit Repair section of the 1989 Service Manual.

SERVICE NOTES:

This change was implemented into some models late in the 1988 model year.

SUBJECT: ------- NEW BACKING PLATE AND SNAP RING FOR 2nd CLUTCH PACK

CHANGE TO ASSEMBLY COMPONENTS: (Figure 11) ------------------------------ A new shorter 2nd clutch backing plate that eliminates the groove and cutouts for the snap ring, replaces the previous 2nd clutch backing plate and snap ring. A new snap ring that is about half as wide as the previous model year must be used with the new backing plate.

DATE OF PRODUCTION CHANGE:

The THM F-7 started using the new backing plate and snap ring at Start Of Production (SOP) 1989.

The THM 440-T4 started using the new backing plate and snap ring on August 22, 1988 (Julian Date 235).

SERVICE ACTION:

DO NOT service the new backing plate (619) and snap ring (620) into a prior year 2nd clutch. This may cause the backing plate to crack if the new 2nd clutch backing plate is used with the old (non chamfered) reaction drum and/or an engine without torque management.

SERVICE PARTS INFORMATION:

Part Model Model Number Description Year Usage ------ ----------- ---- ----- 8668566 Plate, Backing Support Ring 1989 All 8668567 Ring, Snap 1989 All 8662010 Plate, Backing Support Ring 1987-88 All 8661141 Ring, Snap 1987-88 All

Part numbers 8668566 and 8668567 are expected to be available on November 21, 1988. Until then normal part orders will not be accepted by GMSPO. Only verifiable emergency VIP orders will be accepted. GMSPO 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 cancelled as incorrectly ordered while the 400 control is in place.

Part numbers 8662010 and 8661141 are currently available from GMSPO.

SERVICE MANUAL REFERENCE:

This product change does not affect diagnosis for 1989 THM 440-T4 transaxles and is not shown in the 1989 THM 440-T4 Unit Repair Section of your Service Manual.

SUBJECT: -------- NEW SHIFT SPEED AND OIL PRESSURE CHARTS

CHANGE TO ASSEMBLY COMPONENTS: (Figures 12 and 13) ----------------------------- Shift speed and oil pressure charts for the 1989 model year have been changed for new engine calibrations and the addition of three 1989 THM 440-T4 transaxle models.

SERVICE ACTION:

Reference the new shift speed and oil pressure charts when servicing a 1989 model.

SERVICE MANUAL REFERENCE:

This product change information is shown in the THM 440-T4 Automatic Transaxle Unit Repair section of your 1989 Service Manual.

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.