Exhaust Drone Fixed! Spoiler Alert another 3.21 vs 3.92 discussion

[Bmags]

Count yourself lucky i didn't say anything about how stupid this idea is
BTW i wasn't the one who side tracked your thread,i never said squat about you,or your dumb idea,all i did was answer a couple questions,but you feel the need to slander me
Glad to see your buddy Tweedle Dee showed up to help you out Tweedle Dumb.
I'm starting to think you're buddy is "you" with another profile,as nobody can be that gulliable
Seems very suspicious that he showed up when you thought you needed back-up,so i'll give you credit for creating another profile,must be hard to keep them straight though

Haha. What do I need backup for? I explained my solution to a problem (drone is a very real problem) and provided the reasoning behind it. If someone doesn’t like it I couldn’t care less… if there was a real reason not to do it I’d listen… but there isn’t.

 

[G-Ride990]

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[G-Ride990]

Removed off topic posts.

 

[GWillings]

Well, you could just remove the resonators and have the drone just be gone. So there is that.

 

[Black1500Ram]

Just figured I’d throw this out there to the group.

BACKGROUND:
There are many reasons why folks love the 3.92 gears… (way lower 1st gear, lower reverse gear, better acceleration, etc) but for me I mainly was searching for ways to remove my highway drone from my Carven Competitor (which I love)!

Prior to this I had:
1) Solo Performane Mach 44 muffler (too quiet for me, and really the only loud sound was droning)

2) Carven Progressive (loud, but still not loud enough) with a fair amount of drone

3) Carven Competitor (louder still, and frankly the same drone as the Progressive)

In addition to (2) and (3) I also had installed the Mufflex Drone Supression pipe which made things a little better, but the truck was still frustrating to drive for more than 2-3 hours at a time.

I had heard good things about the Corsa Muffler, but it sounds more like a sports car than a V8 truck…

THE SOLUTION:
In general, 7th gear with a 3.21 runs at the same engine speed as 8th gear in the 3.92… which for me cruising at 65+ down the highway keeps my exhaust sounding loud and great with no drone!

What I ended up doing is reflashing my TCM to get rid of 8th gear, so now my truck only runs from 1-7th (giving me what amounts to be the same final gearing as I’d get with the 3.92).

Very happy with how things turned out, and I’m likely the only ZF7 in existence

I have the carven progressive and also started with the mufflex drone pipe. It didn’t make a big difference.

It’s really just a 1/4 wave resonator… and the issue is it’s designed for their exhaust.

So, you have to modify it such that its length coincides with the frequency of the done your exhaust has.

For me that meant shortening it considerably.

Now, 0 drone scientifically

 

[Bmags]

Right, they are just a Helmholtz chamber… nothing really fancy.

I measured the drone frequency with a sound meter in the cab (driving down the highway) and tuned the pipe accordingly... but it didn’t clear it up all the way. Seemed instead like I would decrease the decibels in one range and it would increase in another like playing Whack-a-mole.

I do know the traditional “J pipe” style would be better than the Mufflex setup since the effective length of the pipe “changes” through the curve (resulting in a broader frequency coverage range but less specific suppression)… but that’s a long dang pipe haha.

For the record, I have a Crew Cab with the 6’4” box too, so my exhaust pipe in general is long.

I never tried removing the rear resonators, I had heard mixed reviews where it worked for some people and didn’t for others. Didn't want to have them cutoff just to realize I was still not happy.

Instead, the change to the gearing was cheap, fully reversible, and didn’t require me to lay down on the ground in January.

 

[farout75]

Haha. I will get a full trans tune at some point… but either way I’m still going to keep it out of 8th gear as a requirement.

To me exhaust drone = engine lugging (on top of it being annoying). Even if the tune helps with the constant 7-8th gear hunting I had I LOVE the responsiveness of the truck on the highway now.

And like I mentioned, it’s running the same engine RPM as it would be had I swapped to 3.92 gears so I can’t see any arguments that I’m hurting the longevity of the engine, drivetrain, etc…

You must have good recourses to afford to the lessor MPG and all the gas.

 

[Bmags]

You must have good recourses to afford to the lessor MPG and all the gas.

I'm averaging 17.5MPG with my 7 speed tune. I was planning on swapping the gearing in my truck from 3.21 to 3.92 anyways which would have put me in this exact same boat regardless.

Just to put the numbers here... These are the final drive ratios:
3.21 - 7th = 2.70
3.92 - 8th = 2.62

For all practical purposes those are the same ratio.

Also, with the constant "lugging" of the engine in 8th gear with the 3.21 my previous MPG was only about 18. It was a minimal drop if anything.

 

[Black1500Ram]

Right, they are just a Helmholtz chamber… nothing really fancy.

I measured the drone frequency with a sound meter in the cab (driving down the highway) and tuned the pipe accordingly... but it didn’t clear it up all the way. Seemed instead like I would decrease the decibels in one range and it would increase in another like playing Whack-a-mole.

I do know the traditional “J pipe” style would be better than the Mufflex setup since the effective length of the pipe “changes” through the curve (resulting in a broader frequency coverage range but less specific suppression)… but that’s a long dang pipe haha.

For the record, I have a Crew Cab with the 6’4” box too, so my exhaust pipe in general is long.

I never tried removing the rear resonators, I had heard mixed reviews where it worked for some people and didn’t for others. Didn't want to have them cutoff just to realize I was still not happy.

Instead, the change to the gearing was cheap, fully reversible, and didn’t require me to lay down on the ground in January.

I’m not following you… the mufflex is a 1/4 wave resonator (J pipe).

Does yours look like this? (Minus the leaks and ugly lamps… I’m lazy I know)

It could certainly amplify certain frequencies (harmonics).

 

[Bmags]

I’m not following you… the mufflex is a 1/4 wave resonator (J pipe).

Does yours look like this? (Minus the leaks and ugly lamps… I’m lazy I know)

It could certainly amplify certain frequencies (harmonics).

Yes, but traditionally they look more like a J (tap into the main exhaust pipe then follow parallel to the exhaust)

That way if you measured the length of the pipe from the end to where it connects to the main exhaust it is all relatively the same length.

Since the Mufflex pipe has an extra bend in it, you get a wider range of “lengths” (if you take the inside path vs the outside path).

That results in a wider range of frequency suppression.

To be 100% accurate in this discussion, there is a difference between a Helmholtz “chamber” and a J pipe. The J pipe works based on 1/4 wavelength, and the Helmholtz chamber operates on the volume of air in a chamber.

The buffeting in your cab when you crack just a back window open for instance driving down the highway is due to Helmholtz

 

[Black1500Ram]

Yes, but traditionally they look more like a J (tap into the main exhaust pipe then follow parallel to the exhaust)

That way if you measured the length of the pipe from the end to where it connects to the main exhaust it is all relatively the same length.

Since the Mufflex pipe has an extra bend in it, you get a wider range of “lengths” (if you take the inside path vs the outside path).

That results in a wider range of frequency suppression.

To be 100% accurate in this discussion, there is a difference between a Helmholtz “chamber” and a J pipe. The J pipe works based on 1/4 wavelength, and the Helmholtz chamber operates on the volume of air in a chamber.

The buffeting in your cab when you crack just a back window open for instance driving down the highway is due to Helmholtz

Tickle me curious now! Totally get what you’re saying about the various distancs due to the radii..

 

[rvance]

The 3:21 is the worst gear for these trucks. I have the V6 and my last truck was the 3:55. Huge difference. The 3:21 never goes into 8th except on a steep downhill. If you force it, it just lugs. I have driven a 5.7 rental and it's the same. I want to change my rear gears but I can't decide between the 3:55 and 3:92. I really want the 3:73, but I don't know if I can adjust the ODB for that one. If anyone knows, I would be glad to hear it.

 

[Bmags]

I have a complete 3.92 setup I’d part with, rear axle and front carrier. PM if you’re interested.

Technically nothing needs to change in the PCM or TCM for the gear change. You can update the BCM value to anything you wanted… but it doesn’t effect anything. Speedo for instance isn’t based off the ratio setting.

The only caveat is adaptive cruise control uses it for some things, but if you don’t have that then it’s fine.

If you have the 8 speed tranny and wanted to change gears I would go 3.92 for sure. The others seem like a half measure.

 

[Wild one]

The 3:21 is the worst gear for these trucks. I have the V6 and my last truck was the 3:55. Huge difference. The 3:21 never goes into 8th except on a steep downhill. If you force it, it just lugs. I have driven a 5.7 rental and it's the same. I want to change my rear gears but I can't decide between the 3:55 and 3:92. I really want the 3:73, but I don't know if I can adjust the ODB for that one. If anyone knows, I would be glad to hear it.

I don't think there's 3.73's available for the 1500's,that's more 2500 territory.
You must of been driving an oddball 5.7 if it wouldn't go into 8th with 3.21's,when i had 3.21's in my truck,it'd go into 8th at 50 mph no problem.I switched to 3.55's and in hindsight i wished i'd never made the switch,i prefered the 3.21's over the 3.55's.I made the switch for the dragstrip,and the truck never gained anything at the track.
If i didn't have a $h!tload of money invested in the rear diff with 3.55's in it,the 3.21's would be going back under the truck,as i still have my basically new 3.21 front and rear diffs sitting in my storage shed

 

[Bmags]

I don't think there's 3.73's available for the 1500's,that's more 2500 territory.
You must of been driving an oddball 5.7 if it wouldn't go into 8th with 3.21's,when i had 3.21's in my truck,it'd go into 8th at 50 mph no problem.I switched to 3.55's and in hindsight i wished i'd never made the switch,i prefered the 3.21's over the 3.55's.I made the switch for the dragstrip,and the truck never gained anything at the track.
If i didn't have a $h!tload of money invested in the rear diff with 3.55's in it,the 3.21's would be going back under the truck,as i still have my basically new 3.21 front and rear diffs sitting in my storage shed

I think it also depends on the options of the truck (overall weight for instance) and the terrain where you live. For me if a mouse so much as farts in my direction it would downshift out of 8th. There is just zero power in 8th gear with the 3.21, it’s terrible.

 

[Wild one]

I think it also depends on the options of the truck (overall weight for instance) and the terrain where you live. For me if a mouse so much as farts in my direction it would downshift out of 8th. There is just zero power in 8th gear with the 3.21, it’s terrible.

I live next door to the Rockies.If you know how to drive for milege,they'll shift into 8th with 3.21's with no issue.Hell the cars come with 3.07's behind most R/T Challengers and Chargers,and their tires aren't all that much smaller in diameter then alot of trucks with 3.21's. Any 1500 with the 17" wheel package comes with a 31" tall tire which isn't all that much taller then whats on alot of cars .My 300C has 2.82 gears in it,alot of hellcats have 2.62's,so claiming a truck with 3.21's won't pull 8th is a bunch of malarky,its people who don't know how to drive,not the truck.My driveways elevation is just under 3700ft,so hills are fairly common here

 

[ThunderMug95]

@Wild one You have the paddles? I have been eyeing them, but didnt know you had them!

 

[ThunderMug95]

I have headers with high flow cats, X pipe, running through a single Borla ProXS and I don’t drone.

 

[CanRebel]

I think it also depends on the options of the truck (overall weight for instance) and the terrain where you live. For me if a mouse so much as farts in my direction it would downshift out of 8th. There is just zero power in 8th gear with the 3.21, it’s terrible.

The title and post don't seem to make all that much sense.

You removed last gear because of Done? But at same time, you posted it almost never goes in to 8th or goes in/out of 8th.

Then you posted you have HP Tuner and changed the Trans.

If you have HP Tuner, why you not just Tune it "correctly". In one of your posts, you mentioned to someone, you could tune their trans.
But you are posting you removed 8th gear in your own truck. If for some strange reason your truck is hunting 7-8 gear, correct it.

 

[Wild one]

@Wild one You have the paddles? I have been eyeing them, but didnt know you had them!

My truck was the second one to have them Craig.I've had paddles in my truck since the fall of 2015,love them,lol.

SRT Steering wheel swap

$750.00 Canuck,or about 50 bucks US,lol:naughty:.The replacement factory shift button assembly and the aluminium AMG paddles are the biggest expense,they aren't cheap and make up the majority of the price.He has enough pieces on hand to build one more,after that I don't think he'll build...

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