Removing the drone

[JSmith]

How many of you are using the Donaldson #mo85171 muffler in place of the muffler that came with your 4" system?



Did this eleminate the drone?

How is the sound now?

Are you using one muffler or two?

 

[redeye]

Muffler Placement

I'm removing DD's Walker muffler and having it replaced with the Donaldson late this week or early next. So I'll have the answer soon.



I would like some input on placement? I've read here that moving the muffler forward may also make a difference. What do ya think, any first hand experiences?

 

[Kirwin]

Donaldson Muffler

I have the M018571 muffler on my truck (thanks Jim Leonard) and I don't notice any drone at the speeds/RPMs I cruise at. There is a low speed drone that can develop but you should have already shifted down a gear! I have the stock 3" front pipe with the early 94 3" to 4" mid pipe into the muffler, lost my kitty, then a reducer on the outlet of the muffler to keep my OEM style U-Neek chrome tailpipe.

 

[redeye]

The Donaldson is back ordered, I've heard that Allied is the same muffler, is this true

 

[redeye]

Drone be Gone

I couldn't wait any longer, installed the Allied today.

 

[TPlasek]

Don't leave us hanging... . What were your thoughts on the Allied?????

 

[redeye]

The Walker looks like a glass pack inside, straight through with small perforations the entire length. The Allied is louvered and directional it opens up about halfway through returning to louvers after a couple of inches. By the way that’s how the Donaldson was described here. I’ve heard good things about Rip Rook’s system and checking his site I found the Allied mentioned in his advertisement.



With the Walker there was a sound / vibration (drone) felt in the cab that started at 1950 rpm continuing to intensify until around 2250 rpm dropping off at 2300 rpm. Installing the Allied about halfway between where the stock muffler and resonator used to be shortened the range and intensity of the drone. It now is very short lived, between 1550-1600 rpm, and no where near as loud. It’s a little quieter out the pipe too but performance and temperature seem unaffected.



The difference is night and day I’m very pleased with the results.

 

[jrobinson1]

Donaldson is NOT the same as Allied. It is longer narrower and much quieter. Perforated not louvered.



I am running a donaldson from Stans and an Allied that came from Rip. It is very pleasant in the cab. I personnally haven't been outside while I go by but by the tail at idle it's much quieter. Others say it is very quiet.



A friend put a switched allied to Donaldson and it was a great improvement. Exhaust noise was much lower, especially in the backseat.



The longer mufflers I believe pull more of the resonance out and the further forward they are mounted the better they do. My allied in the back was pretty noisy up front was much more tolerable. Two is the magic.



But I want quiet truck (not all do). Floors and walls are dampened too. All I hear now is my engine no exhaust noise. I like that.

 

[redeye]

GOOD information... . BAD timing

 

[Forrest]

Perforated is far less restrictive than the louvered. Back when the turbo mufflers 1st came out, someone performed a muffler comparison on a V-8 dyno mule. After it was all said & done, they put on glass packs, which are louvered. The glass packs were far & away the lowest performer. Even though the turbo mufflers redirected exhaust flow, the louvers performed worse!



The Donaldson removed the drone on mine.