Attempting to Fix the Drone with Dynamat - 2007 Dodge Charger SRT8 Long-Term Road Test

Edmunds.com

Attempting to Fix the Drone with Dynamat - 2007 Dodge Charger SRT8 Long-Term Road Test

Edmunds.com attempts to fix the exhaust drone from its 2007 Dodge Charger SRT8 with Dynamat.

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desmolicious

Why would you think dynamatting the trunk would get rid of an exhaust drone? It's, umm, coming from the exhaust.

boff

A little searching would have revealed to you that nobody has ever cured exhaust drone with Dynamat. I would suggest welding in a couple of resonators between the cats and mufflers.

ballsonchin

Maybe try install the dynamat inside of the muffler for next weeks post

nate001

I think dynamat was a good (relatively cheap) place to start, but I don't know if the trunk is the right place, the seat backs already divide the trunk from the cabin of the car. I would have started with putting it under the rear seats and then down into the foot wells in the back seat area.

longtimelurker

That's like having a cold house because of one broken basement window - a single-point entry for cold air - and instead of fixing that one broken window, you attempt to find and block all of the hundreds of tiny openings between the basement and your first floor.

The drone is originating in your two exhaust pipes, and it's entering your car via both air transmission, from the tailpipe, and metal transmission up through the car structure. So even if you Dynamat-ed the entire interior surface of the car and installed double-pane glass, the drone would still transmit up through the structure.

The SRT8 boards say that Zoomers (around $1200) or Corsa (around ($1400) are the most quiet aftermarket units. You have already spent around $150 on Dynamat and tools, and what I have to think is around $250 worth of your labor to install the Dynamat. That is $400 and you are really no closer to solving the issue.

s197gt

i've got a touch of drone in my own car. It doesn't appear to be as bad as your case. I had wondered about dynamat. Glad you made the mistake and not me. I have also heard that the best way to fix it is to weld in some resonators before the mufflers.

sxty8stang

Ummm, yeah. Like others have said, this seems incredibly dumb. It's hard to believe you guys couldn't find somebody with a stock system already off their car to sell for cheap. I'm also pretty shocked how expensive aftermarket systems are for that car ($1,400 for Borla S-Type, which is my recommendation). That's higher than C6 Corvette or S197 Mustang systems.

daryleason

Well, on the bright side, if y'all ever decide to kidnap someone and transport them in the trunk, the Dynamat may make it a little quieter ride for them. Plus, there's some padding.

kirkhilles_

So... you have a loud exhaust and your answer is to apply some patches of Dynamat? Are you kidding me? Can't you find some used junkyard exhaust? Couldn't you find an inexpensive aftermarket model? Come on guys. You went all out on the Mustang, but couldn't spent a few hundred on a quieter exhaust?

atari

I posted this in the last drone thread, and it will be the only way to eliminate the drone and keep that exhaust. You need to look into Helmholtz Resonance. A helmholtz chamber needs to be added onto the exhaust. It looks like a "J"-pipe that's welded on. I had an axle back exhaust on my G8 GT that had a J-pipe on it instead of mufflers. I had the mid muffler removed too and replaced with an X pipe, so it was basically a straight pipe setup. Zero drone. Sounded awesome--a nice rumble, but surprisingly not ear-piercingly loud on the outside despite having no mufflers. Search youtube for example videos. It would be a neater project than heading to a junkyard or buying a new setup, and an exhaust shop could probably do it for a reasonable price.

longtimelurker

Now that everyone has pointed out what should have been obvious, here is a constructive suggestion - remember this post?

http://www.edmunds.com/dodge/charger/2007/long-term-road-test/2007-dodge-charger-highs-and-lows-of-the-jba-exhaust.html

This is the maker of the exhaust you have on the car. They are located 45 miles from your offices. Why not take the car there, point out the issue and the exposure the issue has on your website and invite them to take a shot at curing it? They designed it; they should be able to come up with a way to deal with the problem...and they might do it for nothing.

And yes, I think there are plenty of LA-area millenial owners of a car like this that could have come up with this idea all by themselves.

jfa1177

Carlos answered his own question even before they installed the mat. Its used for vibration control, not sound deadening. If you want to truly deaden the sound you need to use the Dynamat in conjunction with some mass loaded vinyl or equivalent. It would need to go in the trunk, cabin floors, and probably the doors.
These guys should have read this first:
http://www.raamaudio.com/pages/How%2dTo.html

and I'm in no way, shape, or form affiliated with RAAM.

thecardoc3

NVH (Noise, Vibration, Harshness) diagnostics and repair can be some of the toughest issues to solve. That being said, there are some routines that do help narrow down the possibilities. The fact that putting the rear seat down has some influence in the sound is an important clue. Going with that fact, the next thing that has to be discerned is how the sound is being transmitted into the car.

One possibility is that the sound is directly transmitted into the vehicle. This could be done by direct contact of the exhaust to some other component under the car, or even excessive stress of one or more hangers. The sound could be audible directly from the source, which means one or two people observing from different locations in the car should be able to point in the direction that the noise appears to be coming from. One of the more difficult possibilities is that the sound as it is being heard inside the car is an echo. One example of this are sounds that are noticed primarily when driving past parked cars, or a wall, but echo's can often be off of the road too. It requires a little imagination applied to where the sound appears to be coming from. If there is nothing in that direct line, then you have to visualize extending that angle down to the road and then to where it reflects back up to the car.

Tools like Chassis Ears can really help identify the sources of certain sounds.

With the history here, I have to wonder if the mufflers simply don't match the natural resonance of the exhaust. It really is a talent to design a system that is agreeable to hear at all of the different engine speeds and loads. Is there a "tinny" aspect to the drone and does it sound like it is coming directly from the mufflers?

throwback

Change the mufflers, that's the only way to get rid of the drone. Dynamat is great for road noise however.

bankerdanny

longtimelurker said:

And yes, I think there are plenty of LA-area millenial owners of a car like this that could have come up with this idea all by themselves.

Maybe, but how many of them would run or write for an influential car blog and thus be someone that the company would have any interest in solving said problem for with no charge?

Having the manufacturer custom re-engineer your exhaust system really isn't an option for the typical owner, regardless of what generation they belong too.

longtimelurker

Then pay for it - but they might have some insight into what might help...it's their system.

defyant15

honestly, i am in the minority here when I say I thought what they attempted was interesting (with dynamat) and a lot of folks would have tried the same. It made for a fun read for sure. No one is currently doing these kind of posts in the blogs or mags.

Tracing down the drone would be a difficult task indeed. I would def inspect the clamps - it could be transmitted through a clamp that is loose/too tight. Especially, if a search shows other people with the same car/exhaust do not have a drone issue.

Another cheap fix would be potentially working with a muffler shop to design a resonator. It may or may not work.

The long term fix is changing the exhaust - but that would be no fun would it!

agentorange

".... and a new original equipment exhaust would cost thousands." Doesn't the average muffler shop have a pattern part that fits for much less? Oh, wait, you don't live in a free state, you have CARB, so that idea is out unless you swap it during a road trip to Vegas.

As for trying to fix an exhaust drone with a sound deadening....bwahahaha!

emajor

The Good: This is an interesting post because it shows the effort involved installing Dynamat, the useless outcome that resulted, and allowed some knowledgeable forum members to explain why.

The Bad: You are still using the budget Millenial Car blah blah excuse to justify it. This exhaust system was a quirk on your particular car, and not every car in this price range will have such an annoying add-on. So paying to fix the exhaust wouldn't violate your Millenial Car Prime Directive. So just do it, document the costs, and revel in the improvement it makes. That will still be good information for someone looking for that budget enthusiast car.

defierro

You need a Heimholtz chamber added to your exhaust.  Any muffler shop should be able to do it....you will need to determine the peak drone frequency first.  The dynamat will make for a quieter ride tho.

G8board.com has a great "Almost drone free" thread

5vzfe

Have you tried selling the Charger? I think the best solution is to sell the car in order to eliminate the drone from your lives. And this is the only solution that you can make money off of. Win win.

banhugh

Dynamat works better if you install it near the receivers of the noise rather than the source. Keep the leftover dynamat to cover the ears of the driver/passengers.

cotak

At 82 db if you drive it long enough, you'll find the whole world start becoming a lot more quiet. As in your'll lose your hearing, problem solved.