NO SERVICE FRONT AXLE ASSY. (REPLACE COMPLETE AXLE ASSY.)

SUBJECT: REPLACING FRONT AXLE PARTS MAY RESULT IN VIBRATION

MODEL and YEAR: 1990-93L-VANS

THIS BULLETIN CANCELS AND SUPERSEDES DEALER SERVICE BULLETIN NO. 92-23-4C. THE 1993 MODEL YEAR HAS BEEN ADDED. ALL COPIES OF 92-23-4C SHOULD BE DISCARDED.

CONDITION:

--------- Each front axle for 1990-93 L-vans is balanced with the pinion flange assembly modified to act as a harmonic member which reduces audible driveline disturbance.

CAUSE:

----- Replacing the ring and pinion gear set, pinion flange assembly, or the pinion bearings will disturb the balance integrity of the axle and result in a vibration.

CORRECTION:

---------- Do not replace either the ring and pinion gear set, pinion flange assembly, or the pinion bearings in a 1990-93 L-van front axle. If replacement of one of these parts is necessary, replace the entire axle assembly, using the system-balanced service axle assemblies listed below.

Prior to replacement of the axle assembly, it is essential that the position of the propeller shaft relative to all of the driveline components be observed and reference marked. When replacing the pinion seal, the pinion yoke must be referenced to the pinion to ensure reassembly in the original position. All components must be reassembled in the same relationship to eachother. Attach propeller shaft to replacement axle first, then to the transfer case, and roadtest. If vibration is noted, re-index propeller shaft to transfer case and test drive again.

SERVICE PARTS INFORMATION:

Axle Part Vehicle Ratio Number Description L-Van 3.42 26022779 Service Axle Assembly, Front L-Van 3.73 26022781 Service Axle Assembly, Front

Parts are currently available from GMSPO.

WARRANTY INFORMATION: For vehicles repaired under warranty, use:

Labor Op: F2142 Labor Time: See Applicable Labor Time Guide

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.