GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1998 🢒 Safari - 4WD 🢒 Driveline/Axle 🢒 Propeller Shaft 🢒 Roughness or Vibration

Checks

Action

DEFINITION: The roughness or vibration occurs while driving the vehicle at various speeds.

A bent or dented propeller shaft

Replace the propeller shaft. Refer to Propeller Shaft Replacement .

Undercoating is on the propeller shaft.

Clean the propeller shaft.

The tires are unbalanced at 48-80 km/h (30-50 mph).

Balance or replace the tires. Refer to Tire and Wheel Balancing in Vibration Diagnosis and Correction.

The universal joints are tight.

Tap the yokes with a hammer in order to free up the U-joints. If you are unable to free up the U-joints, or if the joint feels rough, replace the joint. Refer to Universal Joint Replacement - Nylon Injected Ring or to Universal Joint Replacement - External Snap Ring .

The universal joints are worn.

Replace the worn universal joints. Refer to Universal Joint Replacement - Nylon Injected Ring or to Universal Joint Replacement - External Snap Ring .

Burrs or gouges are on the pinion flange.
    • Inspect the snap ring locating surfaces on the flange yoke.

The propeller shaft or the pinion flange is unbalanced.
    • Check for a missing balance weight on the propeller shaft.
    • Rotate the propeller shaft in the companion flange 180 degrees. Refer to Correcting Driveline Vibration - RWD and 4WD in Vibration Diagnosis and Correction.

Incorrect rear joint angle usually as result of the angle being too large
    • Inspect and correct the trim height at curb weight.
    • Inspect and correct the joint angle. degrees. Refer to Correcting Driveline Vibration - RWD and 4WD in Vibration Diagnosis and Correction.

Excessive looseness at the slip spline

Replace the necessary parts.

Distorted or damaged yokes or flanges

Install new yokes or flanges. Refer to Front Differential Drive Pinion Flange/Yoke, Seal, and Dust Deflector Replacement or Drive Pinion Flange/Yoke and/or Oil Seal Replacement in Rear Drive Axle.

The propeller shaft runout is at 80 km/h (50 mph).
  1. Check the propeller shaft runout.
  2. Replace the propeller shaft if the runout is still over specification. Refer to Correcting Driveline Vibration - RWD and 4WD in Vibration Diagnosis and Correction.