Thread: Dreadful drone
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JFairman JFairman is offline
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Join Date: Jul 2006
Location: S. Florida
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If the droning gradually increased over a few months or whatever I would check to see that the sound absorbtion packing hasn't gradually blown out of the muffler or melted.
If that happened, and it just recently happened to someone that lives near me with one of these mufflers and there's a post about it here the muffler would gradually become louder and if there is a droning at certain rpms than the pitch of the exhaust may be hitting the resonant frequency of the engine bay sheet metal, or possibly the floor pan and rear bulkhead firewall.
If sound absorbtion material has been removed from the floor or behind the back seats to lighten the car, that will just make it louder and more resonant at certain frequencies.

What do you use for sound absorbtion material in your mufflers?

Chopped fiberglass packing blows out of 4 cylinder glass pack mufflers in no time from the exhaust pulses so long strand fiberglass usually stays in place in those applications.
I've also heard of stainlees steel wool fibers being used. Not sure if I've heard of carbon fiber being used in muffler packing.
Old 12-29-2009, 03:30 PM
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