Locking Differential - Chattering on Turns

91chevy19

Number: 91-370-0B

Section: 0B

Date: JULY 1991

Corporate Bulletin No.: 964201R


Subject: LOCKING DIFFERENTIAL LUBRICANT


Model and Year: 1982-91 ALL TRUCKS WITH G80 REAR AXLE


THIS BULLETIN CANCELS AND SUPERSEDES DEALER SERVICE BULLETIN NO. 90-139-4A, DATED JANUARY 1990. CONDITION DESCRIPTION AND CORRECTION HAVE BEEN ADDED AS WELL AS THE 1991 MODEL YEAR. ALL COPIES OF 90-139-4A SHOULD BE DISCARDED.

Some light duty trucks equipped with locking rear axles (G80) may exhibit rear axle chatter, especially when turning a corner from a stop.

This condition of alternate engagement and disengagement of the clutches in the differential assembly is usually caused by contaminated axle lubricant.

To correct this condition, drain and refill the rear axle with SAE 80W-90 GL5 (P/N 1052271). The use of any additive in locking rear axles (G80) is not recommended. Rear axle additives are designed for use in limited slip differentials which are normally installed in cars. All light duty trucks equipped with RPO G80 make use of a locking differential and the use of additives will delay the engagement of the locking mechanism and may decrease axle life.

VEHICLES/COMPONENTS INVOLVED:

Some light duty trucks equipped with locking rear axles, RPO G80.

SERVICE PARTS INFORMATION:

Part Number Description

1052271 Lubricant, Rear Axle (24 oz.)
See Appropriate Parts Manual Gasket, Rear Axle Housing Cover

Parts are currently available through GMSPO.

WARRANTY INFORMATION:

As specified in Light Duty Truck Maintenance Schedules, locking rear axle fluid drain and refill is required owner maintenance at the first engine oil change. Failure to drain and refill the rear axle as specified may contribute to a later axle chatter condition. Refer to the appropriate Light Duty Truck Maintenance Schedule or service manual, section 0B, for further details on change intervals.


For those vehicles repaired under warranty, which have had the axle fluid changed at the first oil change and have experienced rear axle chatter use:

Labor Operation: F2010

Use applicable labor time guide for labor hours.