exhaust drone
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From: utah
exhaust drone
just installed a 4" exhaust on my 95, luv it,except for a drone i get at a certian rpm and speed around 60mph, anyone one else have this problem? and is there any way to get rid of the drone! thanks guys.
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I run a 5" straight system. (no muffler)
the following all helped to reduce interior resonance to the point where it's no longer an issue:
weld as many pipe connections as possible (instead of clamps)
add a couple stiff exhaust hangers to effectively add mass to the pipe and reduce movement/vibration (the pipe itself acts as a big tuning fork)
two layers of 1/8" lead sheet on the back of the cab and the floor behind the seat, one sheet on the rest of the floor and the firewall.
it's quieter inside than it was when I had a 27" long muffler, clamped connections, factory exhaust hangers, and no additional sound deadener.
but it's a hell of a lot louder OUTSIDE!
Forrest
the following all helped to reduce interior resonance to the point where it's no longer an issue:
weld as many pipe connections as possible (instead of clamps)
add a couple stiff exhaust hangers to effectively add mass to the pipe and reduce movement/vibration (the pipe itself acts as a big tuning fork)
two layers of 1/8" lead sheet on the back of the cab and the floor behind the seat, one sheet on the rest of the floor and the firewall.
it's quieter inside than it was when I had a 27" long muffler, clamped connections, factory exhaust hangers, and no additional sound deadener.
but it's a hell of a lot louder OUTSIDE!
Forrest
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From: Sandy, Utah
Originally posted by Eskimo
I had heard about welding/strapping some lengths of angle iron to the exhaust piping... does this not work?
I had heard about welding/strapping some lengths of angle iron to the exhaust piping... does this not work?
Strapping first, so you can move it forward or back till the offending drone is gone.
phox
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Isnt that the reason the factory put the resonator on the newer trucks to kill the resonation or drone.you might put some type of a glass pack on there with the muffler.Alot of resonators are just glass packs.
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the used a resonator because they didn't have to run a catalytic converter which soaks up a lot of sound... the third gen trucks are back to having a cat on them.
strapping/welding angle iron onto the pipe adds density and changes the frequency at which it vibrates. like I said, it acts like a tuning fork... the sound waves inside the pipe cause the pipe itself to vibrate, and those sound waves hammer on the underside and back of the cab.
the stiff exhaust hangers I added are kinda like putting your finger on the tuning fork to keep it from vibrating so loud.
all the sound deadener keeps the sound waves coming off the pipe from being able to vibrate the cab sheet metal (which then creates more sound waves that reach your ears!)
I think the reason you see a lot of straight piped trucks using stock exhaust pipe that don't sound so bad is the factory uses a thicker wall pipe than aftermarket systems, so it resonates at a different frequency.
anyhow, bottom line is there IS a way to have a killer exhaust note without painful interior resonance.
if I had some sort of muffler on my truck, it'd be so quiet inside that I'd fall asleep
I just love the sound of a straight pipe, so I did what I had to do to make it livable... and lemme tell ya, when that 5" straight system first went on, it LITERALLY hurt your eardrums when it hit 2500rpm. from 2100-up it was pretty **** uncomfortable!
Forrest
strapping/welding angle iron onto the pipe adds density and changes the frequency at which it vibrates. like I said, it acts like a tuning fork... the sound waves inside the pipe cause the pipe itself to vibrate, and those sound waves hammer on the underside and back of the cab.
the stiff exhaust hangers I added are kinda like putting your finger on the tuning fork to keep it from vibrating so loud.
all the sound deadener keeps the sound waves coming off the pipe from being able to vibrate the cab sheet metal (which then creates more sound waves that reach your ears!)
I think the reason you see a lot of straight piped trucks using stock exhaust pipe that don't sound so bad is the factory uses a thicker wall pipe than aftermarket systems, so it resonates at a different frequency.
anyhow, bottom line is there IS a way to have a killer exhaust note without painful interior resonance.
if I had some sort of muffler on my truck, it'd be so quiet inside that I'd fall asleep
I just love the sound of a straight pipe, so I did what I had to do to make it livable... and lemme tell ya, when that 5" straight system first went on, it LITERALLY hurt your eardrums when it hit 2500rpm. from 2100-up it was pretty **** uncomfortable!
Forrest
