Ideas On How To Get Rid Of Exhaust Drone?

[Leviticus]

Hey guys,

So I started my day by re-timing my truck and let me tell you, she is running sooo much better!! But anyways, I have been trying to track down a loud drone/whine sound when on the freeway for a while now, it sounded like a bad rear end, so I checked it and it seems fine.

It comes on at about 60-65 MPH which is about 2300-2500 RPM. At 55 its not there, at 70 its not there, let off the go pedal its not there etc. I am pretty much positive it is exhaust drone. I have long tube headers going into 40 series flows with turn outs in front of the rear axle.

I am wondering if anyone has had any similar problems, or has any ideas on how to get rid of this drone, it makes your head hurt after 10 minutes! I know with my later model diesel trucks we have welded weights and such to cut down on drone with custom exhaust, but I am trying to avoid that on this truck.

The PO had the exhaust done by a shop and where the turnouts are, they drilled a bolt hole in the frame, welded a bracket to the pipe, and thru bolted the bracket to the frame with big rubber bushings on both sides instead of a hanger type mount.

Would a cross pipe (H pipe) help you think?

Ok sorry for the long post, as always I appreciate your guys help!

[cdowns]

you could move the mufflers further back in the system to change the harmonics

[Tx Firefighter]

Originally Posted by Leviticus

Hey guys,

So I started my day by re-timing my truck and let me tell you, she is running sooo much better!! But anyways, I have been trying to track down a loud drone/whine sound when on the freeway for a while now, it sounded like a bad rear end, so I checked it and it seems fine.

It comes on at about 60-65 MPH which is about 2300-2500 RPM. At 55 its not there, at 70 its not there, let off the go pedal its not there etc. I am pretty much positive it is exhaust drone. I have long tube headers going into 40 series flows with turn outs in front of the rear axle.

I am wondering if anyone has had any similar problems, or has any ideas on how to get rid of this drone, it makes your head hurt after 10 minutes! I know with my later model diesel trucks we have welded weights and such to cut down on drone with custom exhaust, but I am trying to avoid that on this truck.

The PO had the exhaust done by a shop and where the turnouts are, they drilled a bolt hole in the frame, welded a bracket to the pipe, and thru bolted the bracket to the frame with big rubber bushings on both sides instead of a hanger type mount.

Would a cross pipe (H pipe) help you think?

Ok sorry for the long post, as always I appreciate your guys help!

I'm guessing Cummins ? I always welded a piece of angle iron to the straight pipe section myself.

[kyle fitz]

i had a similar issue on my truck. my mufflers were right under the cab and the tailpipes were just before the rear end. i put some 45 degree tailpipes so it would exit in front the the rear wheels and i have not had a problem since

[Leviticus]

Originally Posted by kyle fitz

i had a similar issue on my truck. my mufflers were right under the cab and the tailpipes were just before the rear end. i put some 45 degree tailpipes so it would exit in front the the rear wheels and i have not had a problem since

Yeah, they turn out the sides right in front of the rear wheels already, thanks for the recommendation though.

[Leviticus]

Originally Posted by Tx Firefighter

I'm guessing Cummins ? I always welded a piece of angle iron to the straight pipe section myself.

Oh yeah, an 04 and an 05, they would shake your fillings loose, we tried welding all kinds of stuff to them until we got it right. They looked like a piece of steel abstract hippy art by the time we were done trying different stuff

[piecesparts]

An "H-Pipe" will always help, if nothing else but to add low end torque. However, having just dealt with my newer Pontiac G8 6.0 engine, customisizing the exhaust and the drone inside it, I would recommend an "X-Pipe" instead. The drone went away and the torque numbers were more than what an H-Pipe would even think about.

['72customdeluxe]

H-pipe, and magnaflows My race bullets are nicer on the highway with a new motor and longtubes than the old one with flow 40's, manifolds, and pinched off piping

[mr48chev]

I had a set of burned out glass packs on duals that exited in front of the rear tires and had that drone until I went with turbos and new pipes that exit behind the tire like they are supposed to.

Different and more flexible hangers might help some but running tailpipes back to where they should exit would be the biggest and best change. You won't get to here it rumble back off the Johnson barriers like you do now but you won't get the headaches either.

[Tom Vogel]

Thats why they use flexible hangers. If that system touchs the frame anywhere, itll make a difference. I am not saying 'thats it', but you should use the rubber hangers.

[chevy_mike]

When I saw the title of this thread, I thought to myself, he's got Flowmaster mufflers. I had a similar problem on my last '68 using FM and I even had the exhaust ran out the back. It used to give me and my wife a headache. Myself and many of my friends who have used FM mufflers have always found at some RPM/Speed a drone. Go to about any other brand of muffler and the problem goes away.

I for one will never use Flowmasters again. My guess is to change your mufflers or live with it. My .02 worth.

[72swb_327stroker_?]

You could always do some sound insulation work..... this will change the comfort level inside the truck and allow you to listen to music, or have a conversation without having to fight road noise!

[Cole Trickle]

Some good sugestions....

What mufflers are you running what motor?

I would try to get the mufflers out from under the cab. X/H pipe will help and the type of muffler plays a big role. A lot of people love that flowmaster sound but they cost you hp and can be anoyingly loud.

I run nothing but magnaflow

[72swb_327stroker_?]

Originally Posted by Cole Trickle

Some good sugestions....

What mufflers are you running what motor?

I would try to get the mufflers out from under the cab. X/H pipe will help and the type of muffler plays a big role. A lot of people love that flowmaster sound but they cost you hp and can be anoyingly loud.

I run nothing but magnaflow

GOOD point!!!!

[piecesparts]

Originally Posted by chevy_mike

When I saw the title of this thread, I thought to myself, he's got Flowmaster mufflers. I had a similar problem on my last '68 using FM and I even had the exhaust ran out the back. It used to give me and my wife a headache. Myself and many of my friends who have used FM mufflers have always found at some RPM/Speed a drone. Go to about any other brand of muffler and the problem goes away.

I for one will never use Flowmasters again. My guess is to change your mufflers or live with it. My .02 worth.

I have three trucks with Flowmaster muffs. Two of them are mid 80s trucks and the other is a 91 daily driver. The Flowmasters are a loud muffler, but as for drone, it is ALL in how you place them and how much insulation there is on the cab. If you are running a cab with very little insulation in them, you WILL get drone, but there is ways around that. I used some pieces of Dynamat to take the tinny metal effect out of the cab and then I did one thing that many do not think of. I went a purchased some foam water line insulation. It hen placed the round insualtion tubes between the cab and the bed, creating a sound barrier to the muffler and road sounds. It works really quite well. I only needed one tube on the older trucks, but the design of the later model truck required a couple tubes to get a good seal.

Make sure that 1) you are running your pipes out from under the truck and 2) you have a good flow path and not a lot of restrictions under the truck. You want that sound at the end of the exhaust pipe, not under the truck.

[ChevLoRay]

Mine has a drone to it, but I kinda like it. The wife doesn't, so I get to drive it by myself. Radio? Don't bother. Have Flowmaster 40's underneath the floor with the exit pipes in front of each rear wheel opening.

My '96 GMC with a 4.3 has a Flowmaster Wannabe on it, and it also has a droning sound. The GMC has more insulation and running the A/C or driving with the windows closed takes care of some of it, but the stock muffler had a harmonic resonance, too.

My '81 El Camino had a pair of baby turbo mufflers and tailpipes out the back. It had a droning sound that I couldn't take, especially on the highway. So, I replaced the exhaust system with new pipes and a muffler from a Buick Regal Grand National. Nice, throaty sound without any annoying resonance. Much nicer to drive.


But my '69 was built to listen to and it will be when it is done, whenever that is.

[packers05]

magnaflows have no drone for me I loved flowmaster until I got these.

[gator2511]

I have super 40's back behind the cab with an H pipe and I still get a drone. I like it!!!!!!!!! If it bugs me I can hit the gvod and the rpm changes and the drone goes away. Guess its just a fm thing. I'd rather listen to the engine than the radio.

[Leviticus]

Originally Posted by gator2511

I have super 40's back behind the cab with an H pipe and I still get a drone. I like it!!!!!!!!! If it bugs me I can hit the gvod and the rpm changes and the drone goes away. Guess its just a fm thing. I'd rather listen to the engine than the radio.

Trust me, there is nothing enjoyable about this drone, and I like loud, I am in Cali so when I hear "smog exempt", I think how loud can I make this thing to piss off the eco hippies

This is more the sound of a police car siren, but in the cab with you, it makes your head hurt! The mufflers are under the rear of the cab, and the direct mount rear hangers are making it worse.

I have an appointment at the end of the week for my buddy at the welding shop to make me some new hangers and install an H pipe, I sure hope it fixes it!