3500 4x4 Pickup L6-359 5.9L DSL Turbo (1996)
Technical Service Bulletin # 18-49-98
Date: 981230
Driveline - Vehicle Surge/Vibration Diagnosis
NO: 18-49-98
GROUP: Vehicle Performance
DATE: Dec. 30, 1998
SUBJECT:
Driveline Induced Vehicle
Surge/Vibration Diagnosis
MODELS:
1996 - 1999 (BR/BE) Ram Truck
NOTE:
THIS BULLETIN APPLIES TO 1500 SERIES FOUR WHEEL DRIVE RAM TRUCKS EQUIPPED WITH AN AUTOMATIC TRANSMISSION
AND A 3.55:1 AXLE RATIO (SALES CODE DMD).
DISCUSSION:
In addition to performing a powertrain diagnosis (using the appropriate Powertrain Diagnostic Manual) for an engine miss/buck/surge/vibration on the
subject vehicles, a diagnosis of the driveline should also be performed.
NOTE:
TECHNICAL SERVICE BULLETIN 18-48-98, DATED DEC. 30, 1998 SHOULD BE PERFORMED PRIOR TO PERFORMING THIS
DRIVELINE INDUCED VEHICLE SURGE/VIBRATION DIAGNOSIS.
Three driveline areas of concern that might induce an incorrect diagnosis of a vehicle surge/vibration are:
^
Driveline Angles
^
Tire Force Variation
^
Differential Ring Gear Pitch Line Runout
Driveline Angle
When two shafts come together at a common joint, the angle that is formed is called the operating angle. Universal joints produce system speed
variations when operating at an angle. This characteristic causes the vehicle propeller shaft to speed up and slow down twice each rotation due to the
working angle at the front of the propeller shaft. The speed variation is canceled at the rear axle when the rear universal joint is operating exactly at the
same angle as the front universal joint. Anytime there is a difference between the front and rear angles of the driveline, driveline roughness will result
and if great enough, a vehicle surge/vibration may be noticed. The larger the angle, the larger the amount of angular acceleration and deceleration at the
joint and the greater the roughness.
Because of their relatively high working angles, four wheel drive and short wheel base vehicles are more sensitive to angular differences. To help
minimize the amount of acceleration and deceleration at the joint, the operating angle of the driveline must be kept to a minimum.
Tire Force Variation
A tire may normally appear to be a true circle with a uniform internal structure. However, due to the construction characteristics of a tire, the tire's
weight, its' internal rigidity, and its' dimensions, tires may have a small amount of variation.
