Noise on deceleration after DD

[battlegraduate09]

I have a stock 2006, just a 4" exhaust system. I knew i was going to turn it up so i went ahead and put a south bend dual disc clutch and smf in it. As soon as the clutch and flywheel were installed, i have this noise on deceleration that is similar to a boost leak, but not shrill like an exhaust leak. the truck was perfect before, only 70,000 miles on it, never tuned its whole life.

I have found that it makes this loud "whooshing" noise only if you let all the way off the accelerator quickly. Like a very light grinding disc on metal, just louder. If you gradually let off the pedal, it doesnt happen. In idle, neutral, i can rev up the engine, no noise. Even in lower rpms, i can shift quicker, just not give it much throttle in between and there is no noise. I figured it was worth it to ask if any have seen this in any clutch installs or what your opinion could be. Before I take it all apart again. Its rather annoying inside the cab. Again it done this as soon as the clutch was installed, everything else was stock.

Thanks in advance,

Josh

 

[battlegraduate09]

Bump

 

[zf>allison]

Bump

Can you post a video of the noise? I don't know why the clutch would do that on a quick release of the pedal. Smf's do transfer alot more noise but I don't know what that would be without hearing it.

 

[battlegraduate09]

I'll try to soon, it almost sounds like turbo bark without the air chopping when it's cold. But it does it all the time if I let off the accelerator

 

[clrussell]

Might be the turbo vanes.. We have a 05 cab n chassis that does this if you drive it just right. His is def turbo

 

[battlegraduate09]

When I heard it on the first test drive I thought turbo. Being all stock, barely 70k miles I was surprised but when you account for the extra load on the engine now with a SMF and dual disc, I thought that weight could embellish an existing issue already in the turbo.

 

[clrussell]

His truck has done it since it was new. Has 200k now. My fx truck doesn't do this but it's tuned so maybe that's the difference

 

[02greysixer]

May try a different tune with different desired vane positions? My auto lly would make a weird woosh between gears with Diablo preditor tuning.

 

[battlegraduate09]

It's been tuned recently. The tuning is great, there is no difference made for this noise though. Tunes 1-5, factory tune, factory tune a couple tweaks. Does it no matter what.

All I know is I brought the truck home 100% stock. Went over it with the tech 2, no issues. Ordered a bunch of parts to make this heavy pig move, put the clutch and flywheel in and this noise appeared instantly. I'm aware of the noise transfer with the clutch itself, I'm fine with that if it will hold 600 horse. The noise doesn't get worse or anything, like I said, it's just annoying after a while

 

[Schwinn68]

Sounds like the whole thing is junk. Better ship it to me here in illinois. I can live with a little whoosh.

J/k buddy!

And I've got a stock LLY turbo sitting here I can ship to you in the morning if you feel like switching the turbo out.

 

[battlegraduate09]

Haha come get it Ben, bring your wallet :thumb: by the way I got a new phone, don't have your number anymore, holler at me sometime.

I appreciate the offer, I might be doing that, Iv got a bunch of parts to put on it but I don't want to get to far until I make sure this isn't an issue. I'm hoping work will slow down this month so I can do some data logging and checking hard parts. Then I will probably just upgrade the turbo anyways.

 

[dmax_ty]

http://youtu.be/PrsAYgMLKlw

Hmmm...does it sound like this?

 

[battlegraduate09]

That's interesting ? What is the details on that truck or did you just find that video ?

 

[dmax_ty]

I've noticed that all 04.5+ trucks will make this sound when they have a stock downpipe and are straight piped.

My LLY did it until the aftermarket DP was added and that was by doing exactly what you described, letting off the acc. quickly and this noise would follow. Easing out of it resulted in no noise. It's not turbo bark or anything of that nature it is just a trait of the stock turbos in our trucks, an aftermarket downpipe will kill the noise.

 

[battlegraduate09]

I guess that makes since. I had an 03 with 5" straight pipe to an 8" stack and it never done this, IHI turbo though. My 2004 and 2008 both had mufflers and aftermarket turbos, twins on the 08, so I guess they wouldnt have done it either. Im still curious as to why it showed up as soon as the clutch was installed but oh well.

Thats great news though, since i have a 3" downpipe sitting in the garage that will be an easy fix and i wont be annoyed as all hell driving my truck anymore. :thumb:

 

[dmax_ty]

Haha yeah there is no cause for concern my friend. Some like the sound and some don't. I like the sound that an aftermarket DP gives the truck. Throatier and that God-awful screech is gonzo.

 

[battlegraduate09]

Well I'm glad I took the day to check it because that fellow ^^ was partly right. It was the downpipe but it was cracked all the way around the flange at the turbo. Couple strikes of the hammer and chisel and it fell out. Bout an hour later I'm test driving and its all good now. Thanks for the tip :thumb: