Moparts
Short Resonator work to get rid of Drone
Posted By: Mopar_Mudder
Short Resonator work to get rid of Drone - 11/04/13 06:32 PM
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?
Posted By: RapidRobert
Re: Short Resonator work to get rid of Drone - 11/04/13 09:29 PM
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
Posted By: Mopar_Mudder
Re: Short Resonator work to get rid of Drone - 11/04/13 10:22 PM
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.
Posted By: RapidRobert
Re: Short Resonator work to get rid of Drone - 11/04/13 10:33 PM
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
Posted By: burdar
Re: Short Resonator work to get rid of Drone - 11/04/13 11:10 PM
Get out the video camera and post an exhaust clip on Youtube.
Posted By: Mopar_Mudder
Re: Short Resonator work to get rid of Drone - 11/04/13 11:11 PM
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
Posted By: ademon
Re: Short Resonator work to get rid of Drone - 11/04/13 11:32 PM
I added some magnaflo resonators just before the tips. Worked great to kill the resonance. But I had more room than what you have.
Posted By: Golden-Arm
Re: Short Resonator work to get rid of Drone - 11/04/13 11:39 PM
wouldn't that "fairly original looking" hemi cuda already have a pair of resonators on it?
Posted By: Mopar_Mudder
Re: Short Resonator work to get rid of Drone - 11/04/13 11:50 PM
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
Posted By: DaveRS23
Re: Short Resonator work to get rid of Drone - 11/05/13 12:47 AM
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.
Posted By: RSNOMO
Re: Short Resonator work to get rid of Drone - 11/05/13 01:24 AM
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...
Posted By: 360view
Re: Short Resonator work to get rid of Drone - 11/05/13 01:15 PM
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.
Posted By: 63stabamatic
Re: Short Resonator work to get rid of Drone - 11/05/13 02:17 PM
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.
Posted By: 8trackbee
Re: Short Resonator work to get rid of Drone - 11/05/13 02:41 PM
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.
Posted By: RapidRobert
Re: Short Resonator work to get rid of Drone - 11/05/13 03:14 PM
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
Posted By: Mopar_Mudder
Re: Short Resonator work to get rid of Drone - 11/05/13 03:28 PM
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?
Posted By: 63stabamatic
Re: Short Resonator work to get rid of Drone - 11/06/13 01:35 PM
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
Posted By: Mopar_Mudder
Re: Short Resonator work to get rid of Drone - 11/06/13 03:23 PM
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.
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Posted By: ademon
Re: Short Resonator work to get rid of Drone - 11/06/13 04:49 PM
24" total length
.jpg "7914134-68RR3834-speed(74).jpg")
Posted By: Colin Frolick
Re: Short Resonator work to get rid of Drone - 11/07/13 06:50 AM
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/
Posted By: Colin Frolick
Re: Short Resonator work to get rid of Drone - 11/07/13 06:51 AM
helped to tone my car down.
Posted By: Mopar_Mudder
Re: Short Resonator work to get rid of Drone - 11/07/13 03:07 PM
Quote:
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/
What you have on your car looks to be longer then the 6-1/2" though isn't it?
Posted By: CUDAJAS
Re: Short Resonator work to get rid of Drone - 11/07/13 03:22 PM
So will the resonator quiet the car down any, or just take care of the drone?
Jason
Posted By: DaveRS23
Re: Short Resonator work to get rid of Drone - 11/07/13 03:35 PM
They might lower the decibel level a bit. They seem to quiet the idle and light throttle more and have less impact on the heavier throttle noise.
I use straight-thru mufflers ahead of the axle and then bullets behind the axle. Makes for a good combo. I can cruise and listen to the radio, drive around the neighborhood and around town without getting the wrong kind of attention. But when I get on it, it cracks pretty good.
And for that extra measure of fun, I also have Doug's cut-outs.
Posted By: Mopar_Mudder
Re: Short Resonator work to get rid of Drone - 11/07/13 03:54 PM
Yea I am not worried about making it any queiter, I just want to get rid of the vibation in the car.
Has anyone ever done anything with tunning forks or added weight to the tail pipes? I know in diesel trucks if you clamp a steel bar anlong the pipe it can help. And some newer vehicles have a tunning fork kinda deal on them from the factory.
Posted By: Colin Frolick
Re: Short Resonator work to get rid of Drone - 11/08/13 05:15 AM
those on my car are about 12" long, on 2.5" exhaust pipes. they are summit brand with louvered baffles inside.
the link was for you!
Posted By: babarracuda
Re: Short Resonator work to get rid of Drone - 11/08/13 02:51 PM
I have Summit 2 1/2 X 12 glasspaks on my 67 Barracuda in the tailpipe. Works great with TTI exhaust!
Posted By: Mopar_Mudder
Re: Short Resonator work to get rid of Drone - 11/08/13 03:11 PM
Quote:
those on my car are about 12" long, on 2.5" exhaust pipes. they are summit brand with louvered baffles inside.
the link was for you!
Yea I am just worried going that short isn't going to have as much of an effect as something like your 12" ones. Gues their is only one way to find out though.....
Posted By: Sunroofcuda
Re: Short Resonator work to get rid of Drone - 11/10/13 04:01 AM
Quote:
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?
The round rear mufflers on a Cuda/Challenger were about 19" long bodied. You should have room for at least 16" of resonator, plus the OE mufflers were 7" diameter. Maybe you need to have a set of new tail pipes bent?? I can build you some resonators...
Posted By: Mopar_Mudder
Re: Short Resonator work to get rid of Drone - 11/11/13 03:27 PM
Quote:
The round rear mufflers on a Cuda/Challenger were about 19" long bodied. You should have room for at least 16" of resonator, plus the OE mufflers were 7" diameter. Maybe you need to have a set of new tail pipes bent?? I can build you some resonators...
I was trying to get away with out modifing the tail pipes that I have. Just cut out the flat section that is available and put a resinator in its place, which is around 8".
I will look at it some more, would rather not go that way unless I have to.
Posted By: 360view
Re: Short Resonator work to get rid of Drone - 11/11/13 05:31 PM
if all you have is that particular 8 inches of space a custom length resonator could be cut down from a longer one.
Resonators are relatively simple inside,
perforated inside pipe
surrounded by a packing of heat resistant fiber
and enclosed in a corrosion resistant cover.
But the longer and larger in diameter a resonator is, the more sound reduction it will accomplish.
Before cutting your existing exhaust system,
make custom 8 inch resonators
and temporarily attach them as exhaust tips
to see if they give you the drone reduction you require.
Instead of mounting such short 8 inch resonators lengthwise,
could you create a cross-over and mount longer resonators from left to right?
Posted By: RapidRobert
Re: Short Resonator work to get rid of Drone - 11/11/13 05:50 PM
Quote:
if all you have is that particular 8 inches of space.
Before cutting your existing exhaust system,
make custom 8 inch resonators
and temporarily attach them as exhaust tips
to see if they give you the drone reduction you require.
Ding ding ding I do believe we have a winna
Posted By: Mopar_Mudder
Re: Short Resonator work to get rid of Drone - 11/11/13 06:02 PM
Quote:
Quote:
if all you have is that particular 8 inches of space.
Before cutting your existing exhaust system,
make custom 8 inch resonators
and temporarily attach them as exhaust tips
to see if they give you the drone reduction you require.
Ding ding ding I do believe we have a winna
Thats not possible when the tips are welded to the exhaust pipe, that is just the way they are on a TTI system 
Posted By: RapidRobert
Re: Short Resonator work to get rid of Drone - 11/11/13 08:59 PM
Quote:
Thats not possible when the tips are welded to the exhaust pipe, that is just the way they are on a TTI system
I guess we dont have a winna
Posted By: Mopar_Mudder
Re: Short Resonator work to get rid of Drone - 11/11/13 09:04 PM
I will just have to start playing around and see what I can do. I could go with something with a 9" body and cut the flanges off. Then weld it right to the tail pipes getting rid of the slip joint. I would rather beable to take it apart in the future but that might be what I have to do.
Posted By: DaveRS23
Re: Short Resonator work to get rid of Drone - 11/12/13 12:57 AM
Is the problem that the pipe over the axle comes down too low and then has to go back up to meet the tip going through the rear pan? Which only leaves that small straight to fit a resonator into?
The surest fix would be to cut out a section of the over the axle pipe behind the axle and move the last turn up to where it more closely aligns with the tip. You will need to remove or change the curves going to the tip, but this will move the resonator up towards the heat shield and make room for a longer resonator.
You will either have to do something like that or else put a much shorter glass pack in the short straight you have now and hope it is enough.
Posted By: Mopar_Mudder
Re: Short Resonator work to get rid of Drone - 11/12/13 03:29 PM
Quote:
Is the problem that the pipe over the axle comes down too low and then has to go back up to meet the tip going through the rear pan? Which only leaves that small straight to fit a resonator into?
The surest fix would be to cut out a section of the over the axle pipe behind the axle and move the last turn up to where it more closely aligns with the tip. You will need to remove or change the curves going to the tip, but this will move the resonator up towards the heat shield and make room for a longer resonator.
You will either have to do something like that or else put a much shorter glass pack in the short straight you have now and hope it is enough.
Yes that is exactly what the problem is. I would rather not cut and start welding / changing the over the axle curve just because it looks nice and clean now. I guess if it comes to that I would problably get entire new pipes made from muffler to tip.
The short bullets aren't to expensive so it doesn't cost much to try. I was just hoping someone had tried bullets that short to give me some feed back.