Moparts
Exhaust Drone
Posted By: AnRT4Me
Exhaust Drone - 06/04/12 08:05 PM
After restoring my 1970 Dodge Coronet RT Convertible a few years ago, I installed a complete 2 1/2 inch TTI H pipe exhaust system on my car. It came with DynoMax Turbo mufflers. They are oval, and the body of them is 20 inches long. The engine is a stock 440 4 bbl, auto trans. with stock exhaust manifolds on it. When cruising between 25 and 45 miles per hour the drone is deaffening!!!!! Once I hit 50 miles per hour and up, it fades into a nice tolerable rumble. But upon letting off the gas pedal and the speed hits 45 MPH and lower, the drone comes back. I called the tech. dept. at DynoMax and they told me it is a 3 chamber muffler and the quietest one they make. Anyone else out there in Mopar Land that has dealt successfully with this problem? Any other mufflers out there that would have a LIGHT RUMBLE WITHOUT the DRONE? Thanks for any and all replies!
Posted By: RapidRobert
Re: Exhaust Drone - 06/04/12 08:45 PM
in addition add a pair of glasspack type muffs alongside the leaf springs to act as resonators
Posted By: rapom
Re: Exhaust Drone - 06/04/12 09:02 PM
Do a search on Moparts. Lots of info on this topic. Just look back one week and you will find stuff.
https://board.moparts.org/ubbthreads/show...e=3#Post7227740
Posted By: patrick
Re: Exhaust Drone - 06/04/12 09:04 PM
this is probably your best bet, as the drone RPM/speed has to do with the resonant frequency of the pipe, which is dependent on it's length (think of a church organ) another option might be to try the dynomax VT series mufflers...
Posted By: 340SHORTY
Re: Exhaust Drone - 06/04/12 09:13 PM
If I said it once Ive said it a hundred times
HOOKER AERO CHAMBERS
Yeah I've got the 3 inch system with 4.10 gears and it is nasty. It's about a zero loss muffler though... I considered the resonator idea. That would probably tone it down.
Posted By: Lefty
Re: Exhaust Drone - 06/04/12 11:20 PM
Quote:
It came with DynoMax Turbo mufflers. They are oval, and the body of them is 20 inches long
That's strange to me as my 66 Coronet convertible w/440 RB; Dougs 2" headers and 2.5" exhaust has no drone whatsoever. I wonder if the 3" pipes is a factor? Or maybe how their hung under the car? 
I've been recommending these mufflers since I put them on the car thinking they were the best, but maybe not...
These are they -
http://www.jegs.com/i/Dynomax/289/17749/10002/-1?parentProductId=
Posted By: Dan Halen
Re: Exhaust Drone - 06/04/12 11:26 PM
Quote:
If I said it once Ive said it a hundred times
HOOKER AERO CHAMBERS
Y-E-S!!!!!! 
I love aerochambers!!
Posted By: kilroy
Re: Exhaust Drone - 06/04/12 11:29 PM
Ive been wondering if some of the drone we all are fighting is the actual muffler is acting like a drum. Maybe by wrapping some fireproof blanket of whatever and then putting some band clamp that you can tighten TIGHT around the muffler to take the high (low?) frequency vibration out.
I havent found a big enough fiberglass blanket yet to try it myself.
Posted By: ThermoQuad
Re: Exhaust Drone - 06/05/12 12:28 AM
Many times drone is caused by the car's state of tune, which typically means the car needs tuning.
Posted By: AnRT4Me
Re: Exhaust Drone - 06/05/12 12:35 AM
Thanks for all of the replies so far, as I will be trying some of these suggestions to get my exhaust OUT OF THE DRONE ZONE!!!!!
Posted By: bboogieart
Re: Exhaust Drone - 06/05/12 01:25 AM
Do your pipes extend passed the rear bumper?
Posted By: jeebis44
Re: Exhaust Drone - 06/05/12 01:19 PM
I have the same problem in my '66 300 w/ 383 and 2.25" straight duals. Mine do come out a few inches past the rear bumper... would adding an x-pipe crossover help?
Posted By: babarracuda
Re: Exhaust Drone - 06/05/12 06:05 PM
I have TTI 3" X pipe exhaust through the super turbo mufflers and 2 1/2" tail pipes. I bought Summit 12" glass packs to cure the drone. If I had more money, I would have bought ultra flows instead of glass packs. I am an old racer and hate giving away any performance.
Posted By: AnRT4Me
Re: Exhaust Drone - 06/11/12 03:48 AM
My exhaust has the stainless TTI tips that extend out under the rear bumper at least 2 inches. I found a set of 10 inch long stainless steel resonators on ebay which I hope to get early this week and install them just in front of the rear tips. I will post the results once I put them on. Thanks again for all the help and suggesstions. MOPARS RULE!!!!!
Posted By: MidPenMopar
Re: Exhaust Drone - 06/11/12 04:32 AM
I just put on these sidepipes after taking off the 3 inch TTI with Dynomax mufflers and no more drone! Yea!!!
Posted By: mnguy55
Re: Exhaust Drone - 08/12/12 04:21 AM
Quote:
Thanks for all of the replies so far, as I will be trying some of these suggestions to get my exhaust OUT OF THE DRONE ZONE!!!!!
I wish I had seen this post before I bought my TTI system. I have a 70 Charger R/T. I just put on the same system you have and it's exactly the same, terrible drone at about 40 MPH. I called TTI and they said they had never heard of a issue with drone with this system. Apparently I'm not the only one.
Have you tried anything yet? I replaced the Dynomax Super Turbos with Thrush Turbos. Same size but different internals. It helped a little but not enough.
Posted By: HemiRick
Re: Exhaust Drone - 08/12/12 04:27 AM
I've noticed the last few times I've driven my Challenger that used to drone, that it has stopped.
Nothing has changed in the TTi 2.5 x pipe exhaust system. I'm glad the drone was annoying.
Posted By: 340SHORTY
Re: Exhaust Drone - 08/12/12 06:21 AM
Quote:
I've noticed the last few times I've driven my Challenger that used to drone, that it has stopped.
Nothing has changed in the TTi 2.5 x pipe exhaust system. I'm glad the drone was annoying.
Thats because youve gone deaf listening to them. lol 
Posted By: cogen80
Re: Exhaust Drone - 08/12/12 11:52 AM
Posted By: 74RALLYE
Re: Exhaust Drone - 08/12/12 03:12 PM
I have the same exhaust system on my 74 Charger with a mild 440. I started with Spin Tech mufflers and the drone was a PIA. I made some inserts for the tail pipe that made it better, but was not the cure. I switched to Dyno Max and the drone was reduced.
2 most common causes for the dreaded drone:
1- The muffler resonates due to a free flowing design and the muffler casing vibrates like a speaker.
2- Tail pipe diameter is the same diameter as the pipes in front of the muffler. The exhaust cools somewhat and the tail pipes can become something like a megaphone. If the tail pipes are 1/4" smaller, drone decreases.
Posted By: 1MYTGTX
Re: Exhaust Drone - 08/12/12 05:55 PM
Cured my Dynomax UltraFlo drone with a pair of Magnaflow bullets on the tailpipes...Hemi style
Posted By: mnguy55
Re: Exhaust Drone - 08/12/12 07:23 PM
Quote:
Cured my Dynomax UltraFlo drone with a pair of Magnaflow bullets on the tailpipes...Hemi style
I'm interested in trying this. Can you tell me what magnaflow muffler you used? Did you weld the tip directly to the muffler or is there a short section of pipe connecting the two?
Posted By: markrr
Re: Exhaust Drone - 08/12/12 08:29 PM
Quote:
Quote:
Cured my Dynomax UltraFlo drone with a pair of Magnaflow bullets on the tailpipes...Hemi style
I'm interested in trying this. Can you tell me what magnaflow muffler you used? Did you weld the tip directly to the muffler or is there a short section of pipe connecting the two?
Please let us know. I'm interested also.
Posted By: 1MYTGTX
Re: Exhaust Drone - 08/13/12 12:33 AM
Quote:
Quote:
Quote:
Cured my Dynomax UltraFlo drone with a pair of Magnaflow bullets on the tailpipes...Hemi style
I'm interested in trying this. Can you tell me what magnaflow muffler you used? Did you weld the tip directly to the muffler or is there a short section of pipe connecting the two?
Please let us know. I'm interested also.
Thanks! Full write up here....
Magnaflow resonators
Posted By: mnguy55
Re: Exhaust Drone - 08/13/12 03:24 AM
Quote:
Quote:
Quote:
Quote:
Cured my Dynomax UltraFlo drone with a pair of Magnaflow bullets on the tailpipes...Hemi style
I'm interested in trying this. Can you tell me what magnaflow muffler you used? Did you weld the tip directly to the muffler or is there a short section of pipe connecting the two?
Please let us know. I'm interested also.
Thanks! Full write up here....
Magnaflow resonators
Thanks for the link. One more question. What tailpipes are you using? (Accurate, TTI, etc) I'm trying to figure out the longest resonator I can fit.
Posted By: 63stabamatic
Re: Exhaust Drone - 08/13/12 01:07 PM
Thanks everyone. I've had the drone with my 2 1/2 inch TTI with H pipe and Dynomax on my 69GTX for years. After reading the posts I ordered a couple Jones 2 1/2 inch, 12" X 4" mufflers, Summit JEX-A4512B, to use as resonators. They're aluminized and a little smaller, just what I wanted. Will report back how they work.
Jim
Posted By: JohnH
Re: Exhaust Drone - 08/13/12 02:32 PM
What is the noise you all are calling drone? Ready to fire up my 440 with TTI's with mild muffles,, need to know what I might expect.... Thanks
Posted By: markrr
Re: Exhaust Drone - 08/13/12 02:49 PM
Quote:
Thanks everyone. I've had the drone with my 2 1/2 inch TTI with H pipe and Dynomax on my 69GTX for years. After reading the posts I ordered a couple Jones 2 1/2 inch, 12" X 4" mufflers, Summit JEX-A4512B, to use as resonators. They're aluminized and a little smaller, just what I wanted. Will report back how they work. Jim
Thanks.
My car is a '69 roadrunner with the same set up as yours, and it drones. I never knew what to call the the sound until this thread.
Posted By: markrr
Re: Exhaust Drone - 08/13/12 02:53 PM
Quote:
What is the noise you all are calling drone? Ready to fire up my 440 with TTI's with mild muffles,, need to know what I might expect.... Thanks
In my case it's sort of a vibrating echo inside the car that pulses or resonates inside at around 2500 or so RPMs. If I speed up, slow down, shift, or do anything to change the RPMs the sound goes away. 
Posted By: bonefish
Re: Exhaust Drone - 08/13/12 03:03 PM
Quote:
What is the noise you all are calling drone? Ready to fire up my 440 with TTI's with mild muffles,, need to know what I might expect.... Thanks
DRONE is the noise you hear when your pipes aint loud enough. 
Posted By: 63stabamatic
Re: Exhaust Drone - 08/14/12 12:32 PM
Quote:
What is the noise you all are calling drone? Ready to fire up my 440 with TTI's with mild muffles,, need to know what I might expect.... Thanks
John, the "drone" is a small point in the RPM range, (2200 or 45MPH on my GTX with 3.23 gears) where the exhaust note gets so loud it's almost painful. I've been avoiding that speed quickly which is possible but I see some of the guys fixed it by putting resontors at the end of the tailpipes like the Hemi cars. I will try this soon.
Jim
Posted By: 70Cuda383
Re: Exhaust Drone - 08/14/12 01:36 PM
yea, drone...hm....how do you describe it... how about, you'll know it when you hear it! it's a hollow echo/ringing type sound that can be deafening.
I cured mine with the 12" summit glasspack as well. I don't see how the resonator/glasspack is going to hurt performance. it's a straight through flow path with louvers cut into the inside flow tube. Plus, it's all the way at the end of the exhaust where the gasses have cooled down some anyway.
Posted By: JohnH
Re: Exhaust Drone - 08/14/12 02:24 PM
Thanks for the info,, I retired out of the Air Force and thought you were talking about a spy plane
... I hope I don't have that noise when I get this car on the road..
Posted By: patrick
Re: Exhaust Drone - 08/14/12 02:29 PM
Quote:
Quote:
Thanks for all of the replies so far, as I will be trying some of these suggestions to get my exhaust OUT OF THE DRONE ZONE!!!!!
I wish I had seen this post before I bought my TTI system. I have a 70 Charger R/T. I just put on the same system you have and it's exactly the same, terrible drone at about 40 MPH. I called TTI and they said they had never heard of a issue with drone with this system. Apparently I'm not the only one.
Have you tried anything yet? I replaced the Dynomax Super Turbos with Thrush Turbos. Same size but different internals. It helped a little but not enough.
try some dynomax VT's if you don't want to put a glasspack as a resonator in the tailpipe
Posted By: babarracuda
Re: Exhaust Drone - 08/14/12 05:10 PM
My 2 1/2 X 12 glass packs slowed my car 1.5 mph. Ive been told since then that glasspacks are the biggest HP robbers of any straight through muffler
Posted By: 63stabamatic
Re: Exhaust Drone - 08/22/12 08:18 PM
Quote:
Thanks everyone. I've had the drone with my 2 1/2 inch TTI with H pipe and Dynomax on my 69GTX for years. After reading the posts I ordered a couple Jones 2 1/2 inch, 12" X 4" mufflers, Summit JEX-A4512B, to use as resonators. They're aluminized and a little smaller, just what I wanted. Will report back how they work.
Jim
I did exactly as described above and it works great! Drone is gone but still a healthy rumble at idle, much more enjoyable on the highway now. You can put the Jones mufflers in two ways, I put them in the maximum through exhaust mode, still plenty quiet.
Jim
Posted By: pinkduster
Re: Exhaust Drone - 08/23/12 02:15 AM
Quote:
DRONE is the noise you hear when your pipes aint loud enough.
Posted By: mnguy55
Re: Exhaust Drone - 08/25/12 05:20 AM
I just added magnaflow 4" mufflers as resonators on my 70 Charger. I just got back from the test drive and it's a sucess. No more drone at 40 & 60 MPH. It still has a very deep sounding idle, a little deeper than I'd like but not bad. Driving is great. Sounds nice but you can listen to the radio with the windows up at 60 MPH. The only bad thing is I now hear a lot more noises that were covered up by the exhaust.
Posted By: A12
Re: Exhaust Drone - 08/25/12 06:07 AM
Some more info and performance results at the end of the thread...........
https://board.moparts.org/ubbthreads/show...part=1&vc=1
Posted By: 1MYTGTX
Re: Exhaust Drone - 08/26/12 12:15 AM
Quote:
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Cured my Dynomax UltraFlo drone with a pair of Magnaflow bullets on the tailpipes...Hemi style
I'm interested in trying this. Can you tell me what magnaflow muffler you used? Did you weld the tip directly to the muffler or is there a short section of pipe connecting the two?
Please let us know. I'm interested also.
Thanks! Full write up here....
Magnaflow resonators
Thanks for the link. One more question. What tailpipes are you using? (Accurate, TTI, etc) I'm trying to figure out the longest resonator I can fit.
The tailpipes are 2.5" from Accurate LTD