Taking the Measure of Automotive Noise Standards, Part 1

Just how loud is that squeaky wheel?

We all know what happens to a squeaky wheel, right? But just how loud does a wheel need to squeak before it’s squeak-worthy of replacement?

During my years of auto repair, one of the interesting tidbits I was hipped to was this: What human ears perceive as a squeak is actually a high-frequency vibration. In the case of vehicle front-end accessory drive (FEAD) applications (e.g., power steering, A/C, alternator), causes of vibration range from worn pulley bearings to inconsistent torque supply. However, the engineering side of this phenomenon is definitely more interesting than the repair side.

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Comments

I wonder ...

I wonder how loud should a car wheel, or belt or any other part squeak before taking the car to the maintenance shop. I wonder how loud should our bone junctions squeak before we go to the hospital. Squeaking is just an age question, gasoline cars last 100,000 miles, diesel cars almost double, trucks 700,000 miles - and they all start squeaking just out of the dealer's shop. How loud squeak earth moving machines? Never noticed? The noise they make go well beyond 90 decibels, but nobody cares. Further on, wheels are not the squeakiest parts of of any car: there are the external mirrors, and the windows that add to; I also wonder why the once highly considered Cx coefficient is not used anymore.