| Subject: | Information on Driveline Vibration Diagnosis (Proper Driveshaft Alignment) |
| Models: | 2003-2005 Chevrolet Kodiak C4500-C5500 Series |
| 2003-2005 GMC TopKick C4500-C5500 Series |
| With Multiple Propeller Shaft Systems |
The purpose of this bulletin is to remind technicians that C4500 and C5500 Series
trucks, with two or more propeller shafts (prop-shaft), have drivelines that are system
balanced. In a two or three prop-shaft system, the prop-shafts are bolted together
and balanced as an assembly prior to being installed in the truck. In a four prop-shaft
system, the rear three prop-shafts are balanced as an assembly and the front prop-shaft
is balanced by itself.
Because the driveline is system balanced, the prop-shafts MUST be properly indexed
when installed in the truck. If a driveline vibration is detected in a C4500 or C5500
Series truck, the first step in a diagnosis is to verify prop-shaft alignment. Look
for the identification label as shown below on the prop-shaft tube near the front
of the prop-shaft. When the prop-shafts are properly indexed, the labels on each prop-shaft
will be in line.
Prop-shafts on C6500-8500 Series trucks are individually balanced and
do not require aligning the identification labels.
