Magnaflow 1900 rpm drone

[jman]

I just changed my exhaust to a Magnaflow "down-pipe" back system and still have the dreaded drone. I think it lowered it from about 2100 to 1900 rpm. At 2100 it is pretty comparable to stock unless you have your foot in it. The system is pretty quiet at any rpm really unless you are accelerating hard and fast.



Does anyone have any ideas to help reduce this. I have read about the Aeroturbine, but would like to know if this will keep things quiet everywhere including the "Drone Zone". I always had the drone, and was hoping the new exhaust would solve it, but it just moved it and made it a deeper drone.



Any advise is appreciated.



TIA

 

[EMD-Run8]

I've got a 4" Banks on mine with an Aeroturbine installed 12" behind the downpipe. I will be taking the Banks muffler out and just leaving the A-T in place soon. Mine does not have any drone whatsoever and A-T has assured me this will not change if the Banks muff is taken out. The only reason I'm taking the Banks out is it's just too dang quiet.

 

[Jeff Clark]

I have the MagnaFlow as well and I do not notice the drone. But I have sound deadener under my carpet, in the doors, and on the back cab wall. It doesn't quiet the road noise not that much, but apperently enough so that I don't notice the drone.



I have an idea..... drive faster

 

[MMeier]

jman, whats the part # on the muffler you used? I believe mine is 12773 or 17223 or something like that, my drone is gone, it is a bit louder overall but that is OK. Others that have used this muffler or have ridden in my truck like it ! Oo. It also knocked my EGT's down 150-200* in any given situation!! Mark

 

[Charliep]

Who bother?

After all the test results reported here, I don't understand why all the $ spent on exhaust changes, but - several years ago the dreaded 4" drone was traced to a harmonic vibration in the long center run of exhaust pipe. It varies from installation to installation depending on how the thing is hung and supported. The "fix" was to stiffen the offending vibrating sections by clamping or welding angle stock along the pipe, thus dampening the vibrations. To verify the root cause, crawl under your rig and watch while a friend runs the engine at the loudest rpm setting. Watch the pipe for vibration - this will tell you where stiffening is required. FWIW, I experienced the same "hot spots" (as I called them) on custom exhaust installations (with glass packs) in several gas rigs I owned over the years. Several of my street bikes have also exhibited the same "hot spots. "

 

[Prairie Dog]

Excellent info Charlie. How big of angle iron is needed and do you put it on two sides?



Thanks,

Scotty

 

[Buffalo]

Hi! Did any of You guys replace "just" the muffler, of did You replace the entire exhaust system. I was thinking of replacing "just" the muffler with a 24" Magnaflow (#12772). The stock muffler has the inlet pipe on the low side and the outlet pipe on the high side. There is approximately a 5-1/2" jog that has to be accomidated. The Magnaflow is a straight through design and doesn't take into consideration that 5-1/2" Jog. If You guys found a fix for this problem I'd sure appreciate hearing about it. Thanks. Joe.

 

[Charliep]

The angle was either 1" or 1. 5" x 1. 8" One guy used a half dozed large muffler clamps, another spot welded them - I think the better solution. I don't know if they are still on file, but the clamp guy posted pictures - you might search 2nd g in '99.

 

[Jeff Clark]

Originally posted by Buffalo

Hi! Did any of You guys replace "just" the muffler, of did You replace the entire exhaust system. I was thinking of replacing "just" the muffler with a 24" Magnaflow (#12772). The stock muffler has the inlet pipe on the low side and the outlet pipe on the high side. There is approximately a 5-1/2" jog that has to be accomidated. The Magnaflow is a straight through design and doesn't take into consideration that 5-1/2" Jog. If You guys found a fix for this problem I'd sure appreciate hearing about it. Thanks. Joe.

You can do that, but the pipe is 3. 5" into the muffler and 4" out. I'm not aware of anyone making a muffler with those dimensions, most will be either 3. 5 on both ends or 4 on both ends. You can install a 4" at an angle and weld up the gap on the front side, or spend a little more and get the whole 4" system. The turbo outlet is still 3. 5" so you don't get all of the benefit of a 4" system unless you upgrade the turbo at sometime. If you have plans on doing that, go ahead and get a new 4" system.

 

[Joseph Donnelly]

Moving the muffler forward or back changes the amount of drone and its rpm. Forward seems better.

 

[jman]

The muffler is Magnaflows 30" muffler. It gave it a deeper note and you can tell when it fires up, but it is very subtle after that and when driving normal. It "honks" a bit when you stand on the noise pedal, but I was expecting that. I think it is a harmonics issue also and the middle pipe is very long, 67. 5" if I remember right. It is almost like someone is holding the tail pipe right behind your head at 1900 rpm and it is a deep, bass sounding drone. I am going to try some muffler clamps and some angle iron to strenghten things up and if that doesn't work I may have to go back to stock and sell the system.



I don't want to do that because I really like the sound, but the drone is way to loud and I am concerned about my 17 month old daughters ears.



Thanks for the help!

 

[jman]

Well I just read about a 1000 posts in the 2nd gen forum on the drone issues and it looks like I might need to add another muffler as far forward as possible. I was thinking of the Aeroturbine, but man those are spendy. I wouldn't mind it a little quieter anyway. I am going to fire Rip an email and get his advise.