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Discussion Starter #1
Adjustable exhaust drone fix: I'm sure most of you have already heard of a Helmholtz resonator to fix the drone of many aftermarket exhausts. My wife's ears seemed to be directly tuned to hear the drone, so I hit all the message boards looking for the exact size, shape, and placement of the resonators. The consensus was the placement and shape doesn't matter much, but the length does. Most thought 26" worked best for our trucks (my local exhaust guy said 22"), but if you add engine mods, the ideal length may change slightly. I went with the 26" recommendation, but added the ability to "re-tune" the resonators later. The resonators can slide 12 inches -- from 22" to 34". It's created using 2 1/4 and 2 1/2 inch pipes and letting them slide inside one another (like a trombone slide), then clamped down. Both pipes were altered slightly to ensure a tighter fit. It works great so far! I need to put it to the ultimate test and put 500lbs in the bed for a "load test". Then have my wife and her bionic ears ride along - total of 600+lbs :) and see what happens. For some reason I am unable to post a pic here (so frustrating...), but if you're interested in seeing it, you'll find a pic or two in "my garage". Hopefully the pics give enough detail, but let me know if they don't and I'll add more.

UPDATE: 1/2/14 - Pics posted below in post #6

Scott

I can't believe I spelled "adjustable" wrong!!!!!
 

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I am guessing you are on this site through internet explorer. Try going on here with firefox and I would bet you can add your pics then. I had the same problem and that was what one of the admins suggested. Pics loaded instantly. I saw them in your garage but if you get the time you should really post them on this thread.
As for the exhaust, nice work. Good for you for doing a ton of research and trying something new. Points sent. You should pm this link to escondidotundra and see what he has to say about your set up. He might want to do some testing on it as well. I am guessing you read his thread "how a properly built exhaust system works"?
One reason for drone might also be using magnaflow. Nothing personal against you but I think they make crap. And I can say that from personal experience since I ran it on my last truck. I hated it. It was tolerable on its own but I also had an AFE CAI and that was a bad combo. On this truck I stayed away from the intake and am running MBRP exhaust. Full 304 stainless and no drone either.
 

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Discussion Starter #3
Thanks Cheapskate. My research did included escondidotundra under another name on tundratalk. I do wonder what he would say... I thought about ordering one of his kits, but I was too impatient and had the day off. :) Besides scaring the heck out of my exhaust guy was more fun. He was nervous; not too nervous to take my money, but nervous nonetheless. I hope others that worry about trying to calculate the exact length use my experience and just go for it. The formula just seems too complicated. The adjustable part costs a little more, but seemed to be worthwhile. And thanks again; always nice to get a thumbs-up. That's two today; the other was my wife. Life is good again.
 

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Pics in this thread would be a plus.
It's not just the length, but where and how you connect it to your exhaust system.

Steve
 

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Hmm. Great idea, I messed with different lengths when designing a 26" resonator. But i agree with you. Not only could different mods cause the potential need for a length besides 26", but different people hear drone differently. I need to make sure that if people order a system and want an adjustable helmholtz it should be available.

Please post pics of ya can. I've got these great wrap around clamps to make it easily adjustable, and am curious to see how others would accomplish this as well.
 

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Discussion Starter #6
Finally got pics to upload. The is a view from front to back. They are installed just a few inches in front of the mufflers (there wasn't much room behind the mufflers-not for 2 of them anyway) and extend forward. The pipes coming out of the actual exhaust line are 2 1/2". The second pipe, the sliding pipes or inside pipes, are 2 1/4". The last couple inches of the 2 1/4" pipes are expanded to snugly fit the 2 1/2" outside pipes. This way, no matter where the slide is finally camped down, the sound waves have the same edge to "hurtle". I didn't think the edge would be a big deal because there are other small imperfections inside exhaust pipes along the way, but nonetheless, I wanted the edge as smooth as possible. I hope I've adequately described this. I wish I had taken a pic before it was fully installed.

Any by the way, I did that "load" test I described in the original post, it worked perfectly. The wife couldn't be happier...

ResonatorFB.jpg

This is closer shot from the same angle.

ResonatorCUClamp.jpg

Side view. You can see the clamps we used.

ResonatorBothClamps.jpg

Please let me know if anyone else would like other details.

Scott
 

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Hey Scott,

I am definitely interested in doing this for my recently purchased 14. (I joined this site looking specifically for a fix for this issue!- my first post!). I just have the stock exhaust and the drone is bugging me! I have big block Chevy hot rods that have less drone than this- if I wanted to hear that lovely noise, I would have bought a Dodge! ;) I am surprised Toyota hasn't cured this.

Any additional advice before I go hacking on my exhaust on a truck with less than a thousand miles on it?!

Thanks!
John
 

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The older (07-08 maybe more?) Tundra's came with factory resonators, and were pretty much drone free. I noticed on my '13, that it did have a very slight drone when it was stock. Not enough to bother me, but everyone is different. I put a dual catback on it, and really get some drone now at certain rpm's.

If you are not planning on going to an aftermarket exhaust, you could probably pick up the tailpipe from an older truck. It should just bolt right on, and has the resonator already in it. And being that they are stainless steel, finding one in very good shape should not be a problem.
 

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The older (07-08 maybe more?) Tundra's came with factory resonators, and were pretty much drone free. I noticed on my '13, that it did have a very slight drone when it was stock. Not enough to bother me, but everyone is different. I put a dual catback on it, and really get some drone now at certain rpm's.

If you are not planning on going to an aftermarket exhaust, you could probably pick up the tailpipe from an older truck. It should just bolt right on, and has the resonator already in it. And being that they are stainless steel, finding one in very good shape should not be a problem.
My 2013 had drone when it had that stock exhaust on it too. It's very mild, but there was definitely a little drone there. Like FL_Tundra, not enough to bother me, but if I was looking for it I could definitely hear it.

How Toyota chose one truck over another to get a tailpipe resonator, or not, is beyond me. 07-09 trucks definitely had a much higher chance of having a resonator, yet there are more without than with. I've seen a few 10-12's with the tailpipe resonators, but I've never seen a 13' or 14' with the resonator. It definitely cuts down on the drone to have the stock tailpipe resonator over not having one.

That said, with or without the factory tailpipe resonator, a BAmufflers bolt in helmholtz resonator will kill your drone;)
 

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They originally "did" cure it. But on later model year trucks they deleted the resonator for whatever reason. I am sure that saving a few dollars was a big factor in eliminating it. Or maybe they thought that we wanted more exhaust noise? Probably came up during one of those mysterious customer surveys in which no one that actually owns a Tundra participated in.
 
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