A/T - Harsh Engagement During Range Selection
87chevy23Number: 88-97-7A
Section: 7A
Date: DEC., 1987
Subject: HARSH ENGAGEMENT
DURING RANGE SELECTION
Model and Year: 1987-88 CELEBRITY WITH
THM 440-T4 TRANSAXLE
TO: ALL CHEVROLET DEALERS
This bulletin covers harsh engagement conditions and specific service information for 1987-88 Celebrity models 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)
I. Harsh Engagement From Park Or Neutral To Drive Or Reverse - 1987-88 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 - 1987-88 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 Number Description
8668121 Reverse Servo Cushion Spring (549)
8668123 1-2 Servo Cushion Spring (559)
8668127 Reverse Servo Return Spring (552)
SERVICE MANUAL REFERENCE:
Refer to the THM 440-T4 (ME9) Automatic Transaxle On Car Service section for appropriate service information.
SERVICE NOTES:
For warranty purposes, use both Labor Operations described below:
Labor Operation K6623 for the reverse servo assembly:
1987-88 - .5 Hour
Labor Operation K6626 for the 1-2 servo assembly:
1987-88 - .5 Hour