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Old 06-02-2013, 04:14 PM   #125
VonMagnum
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Member#: 200781
Join Date: Jan 2009
Location: Ohio
Vehicle:
2015 Forester XT
Venetian Red Pearl

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Quote:
Originally Posted by rationull View Post
But does the noise actually mean the bearings are "garbage" even if we don't know yet if they're prone to early failure?
Typically, a bearing noise means something is creating friction. The louder it gets the more wear is happening and as it grinds down it will eventually seize. A new bearing should make virtually zero noise. A ticking sound indicates rubbing. The louder it gets the more wear is happening. At work, we check machine bearings with a ultrasound meter to locate the bad bearing quickly. When it's pegging around 100dB over a normal/new/typical bearing, it's time to change it to prevent a failure while the machine is running later in the day.

Of course, a noisy bearing may last a good long time and a quiet one can suddenly freeze if something wears really fast for some reason. It's not an exact science, but noise is a good indicator of friction and the whole point of a bearing is a smooth rotational motion. Lack of grease, dust/dirt contamination or excess wear can create more and more friction and therefore it's more and more likely to seize.

So my point was that a bearing that is making noise on Day 1 is probably not the best made bearing in the world. OTOH, I had a bearing squeak on my first car for over 6 years and the TOB never seized.
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