Are You a Vibration and Noise Diagnosis Expert?

Study Notes

Vibration and noise are common complaints from vehicle owners and drivers.
Wheels and tires account for the majority of vehicle vibration problems.
Dampening weights are used to minimize noise, vibration, and harshness (NVH).
A careful analysis procedure should be followed to diagnose assembly or parts problems.
A technician should duplicate the condition by driving the vehicle and observing when and where the vibration is felt or heard.
A neutral run-up test is used to determine if the source of the vibration is engine-related.
Vibration during braking usually indicates out-of-round brake drums, warped disc brake rotors, or other braking system problems.
Frequency is measured in hertz (Hz) and low-frequency oscillations between 1 and 80 Hz are the most disturbing to vehicle occupants.
Tires and wheels are the most common source of vibration in the low-frequency range.
The rolling circumference of the tire is usually shorter due to the contact patch.

Vibration can be measured using a reed tachometer or an electronic vibration analyzer.
Low-frequency vibration (5-20 Hz) is usually due to tire/wheel problems.
Medium-frequency vibration (20-50 Hz) can be caused by imbalances of the driveline.
High-frequency vibration (50-100 Hz) is commonly caused by a fault of the clutch, torque converter, or transmission main shaft that rotates at engine speed.
Incorrect driveline angles are usually caused by worn, damaged, or improperly installed U-joints, worn, collapsed, or defective engine or transmission mount(s), incorrect vehicle ride height, or a bent or distorted driveshaft.
Driveshaft runout should be checked using a dial indicator, and the maximum allowable runout is 0.030 inch (0.8 mm).
Driveshaft U-joint phasing should be checked to see if the front and rear U-joints are directly in line or parallel with each other.
Companion flange runout should be checked, and the companion flange should have a maximum runout of 0.006 inch (0.15 mm) while being rotated.
If the driveshaft is within runout specification and a vibration still exists, the balance of the shaft should be checked and corrected as necessary.
Driveshaft balance is more important than front drive axle shaft balance because a driveshaft rotates much faster.
Driveshaft heavy part should be facing upward.
Corrective weight must be added to opposite side of driveshaft if heavy part is down.
Noise diagnosis is difficult as noise can be transmitted to other places in the vehicle.
Thorough test-drive can help pin down exact location of sound.
Some noises may be normal and should be compared to a similar vehicle.
Noises usually become louder and easier to find over time and mileage.
Repair the cause of the noise instead of using temporary methods.
Almost all vehicle faults cause noise first.
Check power steering high-pressure lines and exhaust system for clearances and stress.
Ignoring noise can lead to more serious and dangerous problems.

Description

Do you hear strange noises or feel vibrations while driving your vehicle? This quiz is for you! Learn about common causes of vibration and noise issues in vehicles, including problems with wheels, tires, and driveline components. Discover how to diagnose and repair these issues with careful analysis procedures and testing methods. With keywords like NVH, driveline angles, and companion flange runout, this quiz will test your knowledge and help you become an expert in identifying and fixing vibration and noise problems in your vehicle.