Diagnosing Vibration

Driving is designed to be a pleasurable experience. Most of the time this is true, but there are moments when that expectation is interrupted by unwanted noises or vibrations. While unwelcome, these may be a valuable clue to a part failure that is developing in your vehicle.


Noise is a by-product of a much more insidious enemy to vehicle parts: vibration – and this enemy is often already beginning to wreak havoc on the vehicle components before the sound reaches your ears.


When a vehicle engine is running, or the car is driving, many vibration sources come into play. OE manufacturers spend countless hours and employ sophisticated techniques in the quest to find and eliminate noises in the vehicle before it leaves the factory.


As the vehicle begins to age, failure and fatigue begin to present themselves in different forms which create a variety of noises. This vibration can affect sensitive vehicle electronic system components and lead to broken parts.


Mechanics have a tremendous challenge of determining what parts are causing the noise. Below we provide a technique to help you systematically diagnose the problem by understanding and identifying noise so that the source can ultimately be discovered and repaired.


Diagnosing Vibration

Vibration diagnosis is best done using an established methodology as you work your way through the vehicle to eliminate possible causes. Here are our recommended steps:


Listen to the driver.

We can’t emphasis this enough. Drivers can often lead you to the problem area by how they describe the sound. They may be able to explain how and when it happens when they drive, or even point out the location it seems to be coming from.


Perform a test drive.

Have the regular driver try to replicate the noise they hear. Observe how they attempt to make the noise happen in their driving motions. Then, as the mechanic, drive the vehicle yourself, paying specific attention to how the vehicle handles. You should note any odd or unusual driving characteristics – something like failed ride control can happen so slowly that a regular driver would not notice it, they just change their driving style to deal with it subconsciously!


Eliminate obvious signals.

Look for worn tires, fluid leaks, grease or oil sprays, worn rubber boots, loose or damaged parts, or even unusual odors - particularly burnt smells! Check springs, rubber couplers and isolators for fatigue or failure. You should always check brake pads, rotors and calipers visually, make sure wheel nuts are at proper torque specification and lastly check steering wheel and pedal feedback when driving.


Check vehicle angles.

This is an extremely important step and is particularly relevant to suspension components. Make sure the vehicle sits at its correct ride height, is balanced in its stance (front/rear view) and level as it sits on the ground (side views). Struts may no longer be supporting the vehicle correctly if springs are weakened. Also check for leaking oil around the strut this would indicate the seals have deteriorated. Finally look at suspension control arms, hubs, drive shafts and CV axles to ensure they are at the correct angles.


Observe if the vehicle is at OE spec.

Sometimes it may be obvious that a vehicle has been modified. Modifications change the dimensional specification and design of the vehicle and can lead to premature wear on some parts, especially if the modification has not been comprehensively engineered.


Dig a bit deeper.

CV axles may require some additional time and effort in order to check the splines and bearing blocks for damage. Any changes to the geometry of the parts will alter the way torque is distributed and result in uneven wearing and failure. The most common sign is a damaged boot and leaking grease.


Don’t just replace broken parts, find the source.

A useful rule of thumb is when you see some signs of wear in a part, (e.g. tires) the damage might be caused by another part of the vehicle that has failed or been damaged. Always check all parts that have direct relationship to the failed part to make sure they have not contributed to its failure. This will ensure you get to the source of the problem and help prevent the customer returning with a newly damaged part that you just installed. Warranty returns in many parts companies point to incorrect diagnosis of the source of the problem. Reduce comebacks by being thorough.


GSP consistently manufactures high quality replacement parts so you can be assured that when you make a repair, you are using the best new parts available. Build a solid reputation for your company by using troubleshooting techniques, being careful in your diagnosis and recommending the best parts available.

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