Clutch - Shudder On Launch

91chevy12

GMC NUMBER: 91-7C-96

GROUP: 7C Clutch

DATE: May, 1991

CORPORATE
NUMBER: 167302


SUBJECT: CLUTCH CHATTER/SHUDDER ON LAUNCH

MODELS: 1988-91 C/K TRUCKS EQUIPPED WITH 4.3L & 5.0L ENGINES AND 4 SPEED & 5 SPEED MANUAL TRANSMISSIONS


Some 1988-91 C/K trucks equipped with 4.3L or 5.0L engines with 4 speed or 5 speed manual transmissions may experience a condition of chatter or shudder on launch.

Revised clutch discs and matching pressure plates have been released for these vehicles and are available through GMSPO. The clutch discs feature a revised facing material which will provide smoother engagement and increased wear resistance. These revised discs can be identified by the name stamp Valeo while the previous discs were stamped Borg Warner. The pressure plates have been revised to work with the discs and must be replaced at the same time. The revised pressure plates will be marked with the name stamp Luk while the previous pressure plate may be marked with the name stamp Luk or Borg Warner. The installation of these parts will provide significant improvement in the involved vehicles.

VEHICLES INVOLVED Some 1988-91 C/K trucks equipped with 4.3L or 5.0L engines and 4 speed or 5 speed transmissions built prior to the following VIN breakpoints:

4.3L/5.0L GMC CHEVROLET
Fort Wayne (Z) MZ516555 MZ159936
Oshawa (1) M1526826 MI 178933
Pontiac (E) ME516465 ME152577

SERVICE PROCEDURE The pressure plate and clutch disc should be replaced at the same time as the parts have been


designed to work together. Refer to section 7C of the appropriate service manual for clutch disc and pressure plate replacement procedure.

Important

Before removing the existing pressure plate, note the location of the paint dab on the pressure plate cover. This paint dab indicates the heavy side of the pressure plate assembly and is aligned with the light side of the engine at the assembly plant. The new pressure plate should be installed with the paint dab in the same location to preserve the balance of the engine assembly.

SERVICE PARTS INFORMATION

ENGINE TRANSMISSION PRESSURE CLUTCH
PLATE P/N DISC P/N

4.3L 4 or 5 SPEED 15668537 15666527
5.0L 5 SPEED 15668537 15668527

Parts are currently available from GMSPO.

WARRANTY INFORMATION

For vehicles repaired under warranty use:

LABOR MODELS LABOR
OPERATION TIME

K0800 C1 C2 C3 2.2 hrs.
K0800 K1 K2 K3 3.0 hrs.
Add K1 K2 K3 with skid plate 0.3 hr.