Front Driveline - Evaluating and Diagnosing Vibration
90chevy28Number: 90-279-4A
Section: 4A
Date: June 1990
Corp.Bulletin No.: 960106
Subject: EVALUATING FRONT DRIVELINE VIBRATION
Month and Year: 1990 L ASTRO VAN
TO: ALL CHEVROLET DEALERS
THIS BULLETIN CANCELS AND SUPERSEDES DEALER SERVICE BULLETIN NO. 90-270-4A, DATED JUNE 1990. THE BULLETIN NO. ON THE FLOW CHART HAS BEEN CHANGED. ALL COPIES OF 90-270-4A SHOULD BE DISCARDED.
The purpose of the bulletin is to provide a logical approach to evaluating and diagnosing vibration and imbalance generated by the front propshaft, front axle or transfer case. The following diagnosis tree is designed to be used as a guide, and when properly utilized, can help isolate and identify causes of front driveline vibration.
Figure 1:
Service Procedure:
Road test vehicle on a smooth, level road to verify customer concern. It is usually beneficial to have the customer present. Note speed and condition at which the disturbance is most noticeable. Follow arrows and perform the required service action. Never bypass or skip a step.