Magnaflow cat-back cabin drone...

[bahollis]

It drones. I knew it would, and when it's just me in the truck with the windows down and the radio blaring running 75 down the tollroad I'm getting exactly what I paid for.

The problem is, when it's me, our 3 year old and my wife in the back with the windows up, radio down, and AC on, running 75 down the tollway I get cabin drone BIG TIME. And it annoys my passengers.

What's the best route to eliminate the drone? Is there a performance loss if I get an inline resonator installed? And, is it even possible on my Tahoe setup? I do't remember there being any straight pipes on that whole kit.

thanks in advance.

Bh

 

[ScottyBoy]

Which magnaflow muffler did you get? Model number?

 

[bahollis]

I got the 15666 cat back system

http://www.autoanything.com/exhausts-mufflers/73A3570A0A0A2585501.aspx

 

[ScottyBoy]

Damn, I was looking at the same muffler that comes in that kit. How bad is the drone, just a lil annoying or is it ridiculously loud? And RPM is your engine running at 75mph?

 

[bahollis]

Annoying. But, like I said... I like the sound. I usually run with the windows down (even in TX right now, 105 yesterday) and with the radio up.

What I don't like is when it goes from my hot rod to a family wagon. No loud radio, windows up, AC cranking... and the kids in the back.

When I am on the highway going under 70, it's barely noticeable. It sounds like road noise. Getting up to 70, it's pretty friggin loud. And cruising above 70 it's as if you had two people in the back of the truck that just hummed all the time... that is what it sounds like.

I am considering one of these over the rear axle, if it will fit.
http://www.horsepowerfreaks.com/partdetails/Vibrant/Exhaust/Exhaust_Resonators//10996

I do like the rumble tho. Even with the drone I'd recommend the setup. Especially the bolt in one. 30 min tops install time.

BH

 

[thumper_ehhhhh]

I tried flowmaster but the drone is still there then flo pro. much better. I would try thet one flo pro muffler

 

[ScottyBoy]

I guess I'm in the same boat as you. When I'm alone in my truck, its basically my speed demon. But its a family wagon when the wife and kids are along. I bet that would get annoying on long road trips with the cruise set on 74 or 75, which is usually what I cruise the highway at. It probly wont be too bad, since I usually have the radio on when driving, even with kids in the truck, just not really loud, but loud enough that I have to turn it down a tad to have a conversation with someone in the back seats.

 

[andrew383]

I have the 12279 (5x8x24) and its not loud at all goin down the road at 70+..

What you can do to to help the drone out is add a bullet muffler in front of the muffler..Magnaflow sells several short bullet style muflers that many have used to fight drone...Really any short race muffler would do the trick

Here's a short magnaflow

 

[bahollis]

Thanks for the replies. Andrew, I'll look into that. I'm not sure there's room enough in front of the muffler because of the curve it takes from the cats to the muffler. Do you think it would work after the muffler as well?


have you ever seen these, or do you think they'd work? http://www.summitracing.com/parts/SUM-692300/
BH

 

[Anthony]

Get a Corsa! No Drone!

 

[KrautBurner]

get a better muffler

mine has no drone
I have the Magnaflow 14377 (4x9x14) (with stock piping)
http://www.magnaflow.com/02product/shopexd.asp?zone=main&id=8680

Inlet/Outlet Size: 2.5in./2.5in.
Body Shape: 4in.x9in. Oval
Core Size: 2.5in.
Body Length: 14in.

 

[bahollis]

Well, unfortunately I'm not looking to replace my system with any other brand... since I just bought it, and I'm not calling any one a liar, but all the posts I read about the 15666 system said it did not drone at all either. So, I guess I got a loud one.
I'll most likely just deal with it.

Thx everyone.

 

[LuSe4]

Maybe your exhaust is vibrating against something. I have the same exhaust on my 2005 tahoe (5.3 liter). I also was concerned about drone, but took the plunge when amazon had them on sale. Mine is virtually silent at 75 with the radio and ventilation off. The only time i hear it is during acceleration.

Check clearances around the exhaust. Good luck!

 

[bahollis]

Hey luse4, did you use a gasket when you bolted on the inlet pipe? Instructions said to replace the existing one, but mine dud not have one

Also, is yours welded?

 

[LuSe4]

There isn't a "gasket", I am not sure what it is called, but where it bolts together there is a rounded protrusion that comes off of the pipe that you bolt to and lines up with the magnaflow pipe. This is the "gasket". (hope that made sense.)

Mine is not welded, either. I bolted mine on in the driveway. I did take it for a test drive and notice it was contacting my trailer hitch on bumps. I had to adjust the pipes some to get the correct clearance.

 

[bahollis]

OK. I thought so. It just seemed weird that the inst. said to remove and keep the gasket for re-installation.

This may be a stupid question, but does most of the noise and vibration exit right at the tips? (like I said, it seems like a "duh" question, but I want to know if I need to check for vibration elsewhere) I know the exhaust does, but does the muffler actually produce any noise that could be loud enough to produce cabin drone?

I adjusted the outlet pipes last night. It was not hitting anywhere, but I did notice that the plastic wheel well in the rear was loose and vibrated when it came in contact with the upper shock bolt, so I fixed that too. I hope that after a few adjustments it will be better. There's no way to lower the whole thing any more without putting pressure on the bolt-on part of the inlet pipe. I don't want to break anything, so I'll keep tweaking it.

thanks.

BH

 

[LuSe4]

I didn't drive it today, so i will check when i get home.

Is there anyway you could have an exhaust leak somewhere? I would say that the majority of the sound comes from the tail pipe.

Try loosening everything and just make sure that all of the pipes are pushed in far enough. Also check that the first pipe (the pipe bolted to the stock exhaust pipe) is not leaking.

Not sure what else it could be besides defective muffler. Maybe call Magnaflow and see what they say.

Maybe post a video from inside while cruising with the windows up and under acceleration if possible.

 

[bahollis]

you know, after securing the two places in the rear quarter that seemed to vibrate, and adjusting the exhaust outlet pipe to be a little further away from that same rear quarter where it exits I think it's a bit quieter. That exhaust has quite a rumble to it, and I could see how under acceleration it might cause vibration in the parts around it.

Now it only sounds like one person humming, but they're all the way in the back!


BH

 

[bahollis]

Update- I took your advice LuSe4, and loosened the entire system, and reseated it all. I thought that when I installed the inlet pipe to the existing exhaust, I may have needed to alternate tightening the bolts a bit to get it to seat straight, so I did that. I completely removed the outlet pipe, and reseated it and repositioned it. I was able to get another 1/2" gap between the stainless tip and the bottom of my rear quarter panel. I drove it a short distance, and it seems to be a lot quieter. I think the system is fine, I just had to tweak it a bit to get it installed correctly.

Thanks again

BH

 

[DJK]

go to a meineke and have them weld in a resonator