A/T - Shudder Upon Apply/Release of TCC

GROUP REF.: Transmission

BULLETIN NO.: 477116

DATE: May, 1994

SUBJECT:
TORQUE CONVERTER SHUDDER (REPLACE TORQUE CONVERTER)

MODELS:
1991-92 CHEVROLET AND GMC TRUCK C/K TRUCKS WITH 5.7L ENGINE (RPO LO5)

TRANSMISSION APPLICATIONS:
1991-92 HYDRA-MATIC 4L60 (RPO MD8)

CONDITION:

Some vehicles may exhibit a shudder upon the apply and/or release of TCC. A shudder may also occur when the [1][2]torque converter clutch is applied and becomes most noticeable under load.

CAUSE:

The apply and/or release shudder may be caused by degradation of the paper based friction material on the damper assembly. The shudder that occurs after the [1][2]torque converter clutch is applied may be caused by the damper springs in the torque converter becoming completely compressed (bottom out) during certain engine operating conditions.

CORRECTION:

Install a new torque converter assembly which has a new carbon based friction material on the damper that improves the apply and release feel of TCC. The new torque converter also has enhanced damper springs to improve the shudder condition while [1][2]torque converter clutch is applied.

DIAGNOSIS INFORMATION:

The shudder may occur during various conditions of TCC usage. Use the following procedure to determine if the vehicle has a shudder concern.

1. Accelerate the vehicle until TCC is applied.

2. Tip into the throttle but not enough to disengage the TCC. A shudder may occur under this condition.

3. While maintaining constant speed, tap the brake to release TCC. During the apply or release of TCC, a shudder may occur.

SERVICE PARTS INFORMATION:

PART NUMBER PART NAME MODELS
8691912 Torque 1KRM, 1KWM, 2KJM,
Converter 1CNM, 1CYM, 2CHM

Parts are currently available from GMSPO.

WARRANTY INFORMATION:

For vehicles repaired under warranty, use:

Labor Operation Labor Time
K7O2O Use published labor operation time.