A/T - THM 440-T4 Harsh Gear Engagement
88cad02Bulletin No. T-88-80
File in Group 7
Number 179
Corp. Ref. No. 877108
Date Jan. '88
SUBJECT: TRANSMISSION HARSH ENGAGEMENT - PARK OR NEUTRAL TO DRIVE OR REVERSE - THM 440-T4
MODELS AFFECTED: 1987-1988 DE VILLES, FLEETWOODS, ELDORADOS, AND SEVILLES
Some 1987-1988 DeVilles, Fleetwoods, Eldorados, and Sevilles equipped with the THM 440-T4 built prior to November 24, 1987 (Julian Date 328), may experience a harsh engagement condition when shifting from park/neutral to drive/reverse.
This condition may be caused by miscalibrated 1-2 and reverse servo cushion springs. Before proceeding with repair, verify that line pressures are within specification. Refer to the appropriate Service Information Manual for line pressure specification and repair procedures for high line pressures.
If line pressures are within specification, repair this condition by installing a new 1-2 servo cushion spring (for harsh engagement into drive or a new reverse servo cushion spring (for harsh engagement into reverse) using the following procedure:
1. Remove the 1-2 servo assembly and the reverse servo assembly from the transaxle. Refer to the appropriate Service Information Manual, Section 7A1 440-T4 Diagnosis and On-Car Service.
FIGURE 1 - 1-2 SERVO AND REVERSE SERVO ASSEMBLIES:
2. Disassemble and replace the 1-2 servo cushion spring (559), P/N 8668123, and the reverse servo cushion spring (549), P/N 8668121, (refer to Figure 1).
3. Install the 1-2 servo assembly and the reverse servo assembly in the transaxle.
If a harsh engagement condition is still evident after performing this procedure, refer to harsh engagement diagnostic procedures in the appropriate Service Information Manual.
For warranty purposes, use Labor Operation T6279 at 1.3 hours for Eldorados and Sevilles, and 1.6 hours for DeVilles and Fleetwoods.