A/T - Harsh Park or Neutral/Drive/Reverse Engagement

87buick11 Bulletin 88-7440-2

Date Dec. '87

Ref. No. 88-056-7440

Corp. Ref. No. 877108


SUBJECT: HARSH ENGAGEMENT CONDITIONS:
I. PARK OR NEUTRAL TO DRIVE OR REVERSE
II. REVERSE TO DRIVE - VEHICLES WITH 2.8L ENGINES ONLY
1987-1988 THM 440-T4 (ME9)

MODELS AFFECTED: ALL 1987-88 CENTURYS, LESABRES, ELECTRAS, RIVIERAS AND REGALS EQUIPPED WITH THM 440-T4 (ME9) TRANSAXLES


BULLETIN COVERS

Harsh engagement conditions and specific service information for 1987 and 1988 cars equipped with a THM 440-T4 transaxle. Other items which cause harsh engagement conditions are:

- vacuum leaks (low vacuum supply to the vacuum modulator) 33-46 Cm Hg (13-18 In Hg) required
- stuck modulator valve
- missing #9 checkball

Figure 1 - THM 440-T4 Transaxle Identification Information:

DATE OF PRODUCTION CHANGE (Figure 1)

November 24, 1987 (Julian Date 328), all THM 440-T4 transaxles were built using a new 1-2 servo cushion spring, reverse servo cushion spring and reverse servo return spring.

Figure 2 - 1-2 Servo And Reverse Servo Assemblies:

SERVICE ACTION (Figure 2)

1. Harsh engagement from park or neutral to drive or reverse - 1987-1988 A, C, H, E cars without 2.8L engines

1. Remove the 1-2 servo assembly and the reverse servo assembly from the transaxle.

2. Disassemble and replace the 1-2 servo cushion spring (559) and the reverse servo cushion spring (549) with the correct part listed in the Service Parts Information section.

3. Install the 1-2 servo assembly and reverse servo assembly in the transaxle.
II. Harsh engagement from reverse to drive, park or neutral to drive or reverse - 1987-1988 A cars with 2.8L engines only
1988 W cars With 2.8L engines only

1. Remove the 1-2 servo assembly and the reverse servo assembly from the transaxle.

2. Disassemble and replace the 1-2 servo cushion spring (559), the reverse servo cushion spring (549) and the reverse servo return spring (552) with the parts listed in the Service Parts Information section.

3. Install the 1-2 servo assembly and reverse servo assembly in the transaxle.

SERVICE PARTS INFORMATION

Part No. Description Usage

8668121 Reverse Servo Cushion Spring (549) All 1987-88 Models

8668123 1-2 Servo Cushion Spring (559) All 1987-88 Models

8668127 Reverse Servo Return Spring (552) 1987-88 Vehicles
w/2.8L Engines Only

SERVICE MANUAL REFERENCE

Refer to the THM 440-T4 (ME9) Automatic Transaxle On Car Service Section for appropriate service information.

WARRANTY INFORMATION

For warranty purposes, use both Labor Operations described below:

Labor Operation K6623 for the reverse servo assembly:

1987-1988 A, E, K Cars - .5 Flour 1987-1988 C, H Cars - .8 Hour 1988 W Car - .8 Hour

Labor Operation K6626 for the 1-2 servo assembly:

1987-1988 A, C, H, E, K Cars - .5 Hour 1988 W Car - 2.1 Hours