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Short Resonator work to get rid of Drone #1528493
11/04/13 02:32 PM
11/04/13 02:32 PM
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Wisconsin
Mopar_Mudder Offline OP
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I have a 3" TTI system with X pipe and their standard Dynomax mufflers. While it sounds good and mean it just has way to much drone for my taste. We are talking rattling sheetmetal and teeth at certain RPM's

I have heard that putting a resonator / bullet type muffler under the trunk where the factory mufflers were will get rid of this.

Problem is I only have about 8" to work with from the bend to where the hanger bracket is that hold the tail pipe up. So it something like the Dynomax Race Bullet #24250 that only has a 6-1/2" body going to me too short to do any good?

Last edited by Mopar_Mudder; 11/04/13 06:23 PM.

1971 Hemi Cuda 2005 SRT-10 Regular Cab Flame Red. 12.771 @ 109.67<---TIME SLIP--Video
Re: Short Resonator work to get rid of Drone [Re: Mopar_Mudder] #1528494
11/04/13 05:29 PM
11/04/13 05:29 PM
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Lincoln Nebraska
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RapidRobert Offline
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Any possiblity of using some longer glasspacks somewhere else in the system? Even ahead of the dynomaxes? www.classicindustries.com has a very nice selection of Mopar items


live every 24 hour block of time like it's your last day on earth
Re: Short Resonator work to get rid of Drone [Re: RapidRobert] #1528495
11/04/13 06:22 PM
11/04/13 06:22 PM
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Wisconsin
Mopar_Mudder Offline OP
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Quote:

Any possiblity of using some longer glasspacks somewhere else in the system? Even ahead of the dynomaxes? www.classicindustries.com has a very nice selection of Mopar items




Not really, ahead of the muffler the pipes are real close to the drive shaft. From what I have read it has to do with the length of the pipe behind the muffle so that is where you need a resonator of some sort to get rid of it.


1971 Hemi Cuda 2005 SRT-10 Regular Cab Flame Red. 12.771 @ 109.67<---TIME SLIP--Video
Re: Short Resonator work to get rid of Drone [Re: Mopar_Mudder] #1528496
11/04/13 06:33 PM
11/04/13 06:33 PM
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Lincoln Nebraska
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RapidRobert Offline
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Since resonators after the muffs is the way pipes are normally routed I had always assumed that that would give the most benefit but I dont know that to be a fact but in your case with the pipes close to the driveshaft it makes that a moot point since you cant do that either. On another site a guy made 2 add on pipes ~1.5 ft iirc & capped on each end & welded them on horizontle at the apex of each arc over the axle & said it made a significant reduction with the noise. Something about the sound waves bouncing back cancelled each other out. If you're back is against the wall on this it might be an option otherwise only a muff change is going to change the tone unless someone has another idea for you


live every 24 hour block of time like it's your last day on earth
Re: Short Resonator work to get rid of Drone [Re: RapidRobert] #1528497
11/04/13 07:10 PM
11/04/13 07:10 PM
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Iowa
burdar Offline
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Get out the video camera and post an exhaust clip on Youtube.

Re: Short Resonator work to get rid of Drone [Re: RapidRobert] #1528498
11/04/13 07:11 PM
11/04/13 07:11 PM
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Wisconsin
Mopar_Mudder Offline OP
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Quote:

Since resonators after the muffs is the way pipes are normally routed I had always assumed that that would give the most benefit but I dont know that to be a fact but in your case with the pipes close to the driveshaft it makes that a moot point since you cant do that either. On another site a guy made 2 add on pipes ~1.5 ft iirc & capped on each end & welded them on horizontle at the apex of each arc over the axle & said it made a significant reduction with the noise. Something about the sound waves bouncing back cancelled each other out. If you're back is against the wall on this it might be an option otherwise only a muff change is going to change the tone unless someone has another idea for you




I had heard about the add pipe also and I think it problably does work. But I really don't want to do that to the car. Think it would look a little tacky on a fairly original looking Hemi Cuda


1971 Hemi Cuda 2005 SRT-10 Regular Cab Flame Red. 12.771 @ 109.67<---TIME SLIP--Video
Re: Short Resonator work to get rid of Drone [Re: Mopar_Mudder] #1528499
11/04/13 07:32 PM
11/04/13 07:32 PM
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ademon Offline
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I added some magnaflo resonators just before the tips. Worked great to kill the resonance. But I had more room than what you have.

Re: Short Resonator work to get rid of Drone [Re: Mopar_Mudder] #1528500
11/04/13 07:39 PM
11/04/13 07:39 PM
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Sunny South Florida
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wouldn't that "fairly original looking" hemi cuda already have a pair of resonators on it?


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Re: Short Resonator work to get rid of Drone [Re: burdar] #1528501
11/04/13 07:50 PM
11/04/13 07:50 PM
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Wisconsin
Mopar_Mudder Offline OP
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Quote:

Get out the video camera and post an exhaust clip on Youtube.




I could but compressed video really does nothing to get good sound of what exaust sounds like I have found. Plus it would be real hard to pick up drone.

This doesn't do alot but the best and only thing I have right now:

Video


1971 Hemi Cuda 2005 SRT-10 Regular Cab Flame Red. 12.771 @ 109.67<---TIME SLIP--Video
Re: Short Resonator work to get rid of Drone [Re: Mopar_Mudder] #1528502
11/04/13 08:47 PM
11/04/13 08:47 PM
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DaveRS23 Offline
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I always use short cheap glass packs/bullets behind the axle to control the drone. It is very effective, even when used with a straight-through system.


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Re: Short Resonator work to get rid of Drone [Re: Golden-Arm] #1528503
11/04/13 09:24 PM
11/04/13 09:24 PM
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Quote:

wouldn't that "fairly original looking" hemi cuda already have a pair of resonators on it?




That'd be the way I'd approach it...

Re: Short Resonator work to get rid of Drone [Re: Mopar_Mudder] #1528504
11/05/13 09:15 AM
11/05/13 09:15 AM
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USA
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360view Offline
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What is the distance in inches from rear of muffler to end of exhaust pipe at rear?

This distance determines the RPM at which drone is loudest at cruise.

Throttle opening also affects drone.
At a completely steady Speed and therefore RPM does the drone change when the car climbs a hill on the highway?

You can run the simple experiment of temporarily adding extensions to your tailpipes and seeing if the drone noise shifts away from your cruising RPM.

Re: Short Resonator work to get rid of Drone [Re: 360view] #1528505
11/05/13 10:17 AM
11/05/13 10:17 AM
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Palmyra, NY
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63stabamatic Offline
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Adding small glass-packs before the tips got rid of my drone at 45MPH or around 2200 RPM's. The B body Hemi's all had them.

7912850-DSCN1571.JPG (415 downloads)
Re: Short Resonator work to get rid of Drone [Re: Mopar_Mudder] #1528506
11/05/13 10:41 AM
11/05/13 10:41 AM
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west australia
8trackbee Offline
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I remember Richard Erinburg did a bit on your problem...mopar action... you could find that write-up, I think you may have a problem with the mounting of the exhaust tranfering vibration into the car.

Re: Short Resonator work to get rid of Drone [Re: 8trackbee] #1528507
11/05/13 11:14 AM
11/05/13 11:14 AM
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RapidRobert Offline
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good stuff what 360view said. You might go ahead & use those short dynomax bullets & see if there is a good gain. As you know a person wouldn't want to use glasspacks that neck down at the end nipples which the cheap ones do but I'm assuming they are good ones like the ones in Stabamatics'pic. Holler how it turns out


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Re: Short Resonator work to get rid of Drone [Re: 63stabamatic] #1528508
11/05/13 11:28 AM
11/05/13 11:28 AM
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Wisconsin
Mopar_Mudder Offline OP
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Quote:

Adding small glass-packs before the tips got rid of my drone at 45MPH or around 2200 RPM's. The B body Hemi's all had them.




Can you tell me how long the body is on thoose that you put on?


1971 Hemi Cuda 2005 SRT-10 Regular Cab Flame Red. 12.771 @ 109.67<---TIME SLIP--Video
Re: Short Resonator work to get rid of Drone [Re: Mopar_Mudder] #1528509
11/06/13 09:35 AM
11/06/13 09:35 AM
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Palmyra, NY
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63stabamatic Offline
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They are Summit JEX-A4512B around 12". They have two different back pressures modes depending on polarity, I have mine in minimum back pressure polarity.

Jim

Re: Short Resonator work to get rid of Drone [Re: 63stabamatic] #1528510
11/06/13 11:23 AM
11/06/13 11:23 AM
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Wisconsin
Mopar_Mudder Offline OP
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Quote:

They are Summit JEX-A4512B around 12". They have two different back pressures modes depending on polarity, I have mine in minimum back pressure polarity.

Jim




Thanks for the info. I will have to do some more looking at it to see if I can get anything longer in. I know to go over 10" I am gooing to have to do some major modification.

Not a great picture but all I could find right now.




Last edited by Mopar_Mudder; 11/06/13 11:46 AM.

1971 Hemi Cuda 2005 SRT-10 Regular Cab Flame Red. 12.771 @ 109.67<---TIME SLIP--Video
Re: Short Resonator work to get rid of Drone [Re: Mopar_Mudder] #1528511
11/06/13 12:49 PM
11/06/13 12:49 PM
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ademon Offline
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24" total length

Re: Short Resonator work to get rid of Drone [Re: ademon] #1528512
11/07/13 02:50 AM
11/07/13 02:50 AM
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Southern CA
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yeah squeeze some short bullet mufflers in there. the longer the better but this one is only 6.5" long, since you said that's about all the room you have. 4" overall diameter.

http://www.summitracing.com/parts/wlk-24250/overview/

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