B4000 V6-4.0L SOHC (2005)
DRIVELINE / AXLE VIBRATION ANALYSIS
Warning:
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A vehicle equipped with a Traction-Lok differential will always have both wheels driving. If only one wheel is raised off the floor and the
rear axle is driven by the engine, the wheel on the floor could drive the vehicle off the stand or jack. Be sure both rear wheels are off the
floor. Failure to follow these instructions may result in personal injury.
Few vibration conditions are caused by the front or rear axle. On a vibration concern, follow the diagnosis procedure in SYMPTOM
TROUBLESHOOTING CHART - DRIVELINE / AXLE, unless there is a good reason to suspect the axle. See: Transmission and Drivetrain/Drive
Axles, Bearings and Joints/Testing and Inspection/Diagnosis By Symptom/Symptom Troubleshooting Chart - Driveline / Axle
TIRES
Warning:
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Do not balance the wheels and tires while they are mounted on the vehicle. Possible tire disintegration/ differential failure could result,
causing personal injury/extensive component damage. Use an off- vehicle wheel and tire balancer only.
Most vibration in the rear end is caused by tires or driveline angle.
Vibration is a concern with modern, high-mileage tires if they are not "true" both radially and laterally. They are more susceptible to vibration around
the limits of radial and lateral runout of the tire and wheel assembly. They also require more accurate balancing. Wheel and tire runout checks, truing
and balancing are normally done before axle inspection.
DRIVELINE ANGLE
Driveline angularity is the angular relationship between the engine crankshaft, the propeller shaft, and the rear axle pinion, Factors determining
driveline angularity include ride height, rear spring, and engine mounts.
Driveline Angle
An incorrect driveline (pinion) angle can often be detected by the driving condition in which the vibration occurs.
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A vibration during coastdown from 72 to 56 km/h (45 to 35 mph) is often caused by an excessive U-joint angle at the axle (pinion nose
downward).
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A vibration during acceleration, from 56 to 72 km/h (35 to 45 mph) may indicate an excessive U-joint angle at the axle (pinion nose upward).
When these conditions exist, check the driveline angles.
If the tires and driveline angle are not the cause, perform the NVH tests to determine whether the concern is caused by a condition in the axle.
