Drone from exhaust - how to fix or reduce??

[DylanR]

I have a custom exhaust similar to a rock basher exiting right before rear axle. Love the sound very deep... I’ve posted about it before.
My issue is around gear 5-6 there is some serious drone. Especially towing my boat. I would like to reduce that...
If it’s just a little bit better that would be great. I know my wife hates it. Before I waste half a day going to the muffler shop what ideas would help... trying to keep the sound I have but get rid of the drone.

1. just add another muffler
2. Extend on out to exit behind rear tire
3. Thinking about adding a dual exhaust
4. I have heard cold air intakes reduce drone???

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[Renegade]

It’s going to be very difficult to give you a 100% answer, not knowing exactly what you have done to yours, but adding a resonator is A possible solution. The stock exhaust has two, one before the muffler, and one after. I’m guessing you removed them both with your “rock basher” (whatever that is).

 

[Jt-wrx]

it's awful, 2000 rpm under load can be painful for real, i went magnaflow street series side exit and it's as far as i would go, i eliminated the first two mufflers initially but one highway trip and i ordered the magnaflow when i got back

somebody here did a j-pipe that cured the drone, find that thread, could be your solution

 

[cecaa850]

somebody here did a j-pipe that cured the drone, find that thread, could be your solution

That was me. It totally eliminated my drone. OP. what rpm is it the worst?

 

[whiteglad]

placement of the muffler can matter. Usually, the farther forward, the better to reduce drone.

 

[Flexin]

In your instance, I would just put the stock one back on. Just cutting the pipe and deleting can give unexpected results. Either that or go with one that's been tested already.

 

[whiteglad]

I replaced the front resonator with a piece of 2.5" pipe, 25" long, expanded to 2.58" ID at the ends to fit over the pipes in front of and behind the resonator. I did it to get another 2" ground clearance, and noted no significant change in exhaust sound

 

[cecaa850]

Drone is fixable. Guess he's moved on or accepted it.

 

[Halfcabnut]

Hello would just like ro day Thanks to Dylan R for the write up on the Welded Thrush ,and to Cecaa 850 for the J Pipe Helmholtz Ideal.
I installed the Thrush Welded muffler similiar to Dylan other than i did run mine all the way to rear as the stock location was. Like Dylan at 2100 to 2500 drone was fairly bad. After reading Cecaa 850 fix for the problem I fabbed up a J pipe very similar to his description. Absolutely Drone free !
Sounds great now. Great Sound when accelerating very quiet at cruising .
2000 -3000 rpm is zero Drone ..
Thanks so much for the help ! Definitely sent me in the right direction..
Great information in this forum ..

Dan

 

[oldhp3]

Did any of these exhaust modifications actually do any good for real power or MPG increase? Not rear end dyno or "pretty sure it gets better MPG." The biggest restriction in these little engines is the catalytic convertors. I floor mine from a stop, it shifts at 6600RPM and tops out at 110 MPH. I know it would go faster but ECU stops it.

 

[ShadowsPapa]

Did any of these exhaust modifications actually do any good for real power or MPG increase? Not rear end dyno or "pretty sure it gets better MPG." The biggest restriction in these little engines is the catalytic convertors. I floor mine from a stop, it shifts at 6600RPM and tops out at 110 MPH. I know it would go faster but ECU stops it.

Would love to see if any JT owner has done an honest before and after dyno check. I mean changing NOTHING else - no pedalcommander or other stuff - dyno the beast, swap exhaust, dyno it again (same weather, same ambient temp, same relative humidity)

As far as drone - PIPES matter, mufflers matter, length of the pipes matter.
If it was true dual exhaust I'd suggest an X or H pipe configuration.

 

[j.o.y.ride]

I have never noticed any drone at all

But someone on here had posted shots of a J pipe. If you can determine the frequency of the drone you can have a J pipe installed that should work to be 180* opposite wave to cancel it, same thing noise cancelling headphones do.

https://www.jeepgladiatorforum.com/forum/threads/exhaust-upgrade.33722/#post-547046

 

[ShadowsPapa]

I have never noticed any drone at all

But someone on here had posted shots of a J pipe. If you can determine the frequency of the drone you can have a J pipe installed that should work to be 180* opposite wave to cancel it, same thing noise cancelling headphones do.

https://www.jeepgladiatorforum.com/forum/threads/exhaust-upgrade.33722/#post-547046

Good explanation comparing to the headphones. It's how my hearing aids work as well in the noise cancelling program I have set up - choose that program through my phone app if the JT is noisy due to wind and they cancel it out. Nice for when the freedom panels are out or the roof off.
When I studied performance exhaust a few years back, one guy compared exhaust notes - or waves of air moving through an exhaust pipe to how an acoustic guitar works.

 

[Halfcabnut]

Oldhp3
Honestly to early for me to tell. However that wast my goal. My goal was to actually achive a bit of soumd i could hear.
My JT is a manual and ive always drove manuals somewhat by ear . The stock system surrpresed the note so well you just couldnt hear it.
Now i have just enough of sound needed for me without sounding like wound up buzz saw.
Goal achived ..
Dan

 

[whiteglad]

today's catalytic converters are much less restrictive than those of the 1970s. One set of exhaust tests with acceleration times was done by JK gear and gadgets. They got improvements from ball joint back systems, particularly the afe rock basher, but no measurable improvement from the bigger afe cat and head pipe systems. I think the rock basher was 3" diameter and of course dumps in front of the rear axle with just one muffler.

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