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Thread: Need some help identifying a mystery "howl/vibration" noise.

  1. #1
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    Unhappy Need some help identifying a mystery "howl/vibration" noise.

    I need some help identifying a loud noise coming from the front of my Talon.

    I've been slowly building my 1994 Eagle Talon since the Spring of '06, during which time I've been accumulating parts, taking things out, putting things back in, buying better things etc. She's finally been put back together and I was really, REALLY looking forward to breaking the car in but I've hit yet another snag.

    When I took the car out for an initial shakedown pass I noticed a very loud howl or whine type noise when I get the car up to around 45/50mph and then put into 3rd to decelerate. This noise also happens in other gears but it's ONLY when I decelerate and it only happens when I decel from about 50mph to 30mph. I have not gone any faster than that, but the sound is definitely coming from the front passenger area of the vehicle.

    While building the car I replaced the brakes with a wilwood kit from Todd at TCE, the trans is a brand new shep stg 4, and the tcase is in known working good condition. I also installed a PTT twin-disc clutch at the time the trans was put back in and I *think* it might be the clutch but I'm not sure.

    Any help would be appreciated at this point, and I've also made a video so you can hear what noise I'm referring to. The noise hits at approximately 21 seconds and lasts during decel until around 32ish seconds. I'm sorry about the camerawork, it's taken on an old iphone in a rough riding TSi but it's more for the sound anyway.

    Thanks for your help, and let me know if you need any more information than what I've provided.
    Cory O.
    '94 TSi AWD | '92 GVR4 | '02 Xterra SE 4x4
    If at first you don't succeed, buy a few more.

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    I experienced something similar to this once, and it was loose flywheel bolts. Just like your instance, I heard the noise only on decel. My noise sounded slightly different, but that is most likely because I had an ACT streetlight flywheel and 2100 clutch at the time.
    -J.P.
    1991 Eagle Talon TSi FWD

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    I had a similar noise come on after putting a brand new ACT2600/street disc in my 1G years ago. I never "figured it out," but I never broke anything. I eventually replaced that clutch prematurely and kept it around for a spare. My noise went away. I ended up giving the used clutch to a buddy, and it made the same noise in his car. The noise only happened on deccel and only in a certain speed range.
    92 Talon AWD - Garage Queen
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    Sounds like an unsprung clutch hub to me. The few DSMs I've been in with a twin disc or unsprung hub has made that noise, although yours seems fairly mild. The twin disc I ran did this, and it's fine at the track but a pain in the ass for long distance highway use.

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    Crap I must have been delirious from the heat out when I posted this, could a moderator please move this to the "public tech" forum?

    After reviewing the answers here, doing a bit of research elsewhere, and then finally talking to Shep himself I guess this is pretty normal with any kind of clutch that uses an unsprung hub(s). I'm actually a bit surprised that I haven't heard anyone else mention it really but ah well. Thanks for the input fellas, I guess we're all go for breaking her in
    Cory O.
    '94 TSi AWD | '92 GVR4 | '02 Xterra SE 4x4
    If at first you don't succeed, buy a few more.

  6. #6
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    Quote Originally Posted by Cory O. View Post
    I'm actually a bit surprised that I haven't heard anyone else mention it really but ah well.
    I've seen a few discussions in the past about vibration on decel. There was always a new guy coming in and saying, "well it's definitely x because I replaced x and it went away." Then another guy would have also replaced x, plus y, z, q, k, r, etc. and still not have gotten rid of the noise. This is the first time I've heard of it being an unsprung hub on a clutch too. Seems reasonable if Shep said it.
    The Internet: Where people who can't build sentences try to build cars.

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    Just to add another data point, everytime I have used an unsprung hub clutch I have had this noise on decel. The first time I put one in years ago I had the noise. I did some research and found this on RRE'S site:

    "Also most puck clutches have a solid hub center that will contribute to horrible coast down gear noise (worse in an AWD)."

    http://www.roadraceengineering.com/c...ywheeltech.htm

    It's under the section called "Metallic Puck Style Clutch Discs"

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    Thanks for the additional input guys, I actually spoke with steve fox the other day (can't get off the phone with that guy in under 45 minutes, it's just impossible) and after beating me up with engineering that goes way over my head we came to the conclusion that it's "a vibration issue" that might be solved by dumping my fliudampr and going with an ATi damper. I'm hesitant to throw out a perfect fluidampr and drop $460.00 on a hunch that may or may not do anything at all but at this point I might give it a shot. Steve mentioned that the ATI dampers can be "tuned" for strokers etc but when I called ATI they simply said they have different rubbers and each one is just tuned for a different RPM range. Since I will RARELY see over 8200rpm in my stroker application they said the stock rubber will be fine. We'll see.
    Cory O.
    '94 TSi AWD | '92 GVR4 | '02 Xterra SE 4x4
    If at first you don't succeed, buy a few more.

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    My ACT 2600 with the unsprung street disc makes the same coffee grinder noise during deceleration.

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    I've noticed this noise is louder with a lighter flywheel. My Talon with a Fidanza flywheel is much louder than my VR-4 with an ACT chromoly flywheel. All sprung ACT2600 setups though. I always assumed it was the lighter flywheels not being able to dampen harmonics as well as a stock flywheel.
    91 TSi AWD - 10.96 @ 125.02 - cornfed evo3
    10.68 @ 133.2 - cornfed DSM76

  11. #11
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    My talon is using an ACT x-act chromoly flywheel and an unsprung ACT disc. It makes a very similar noise to the noise in which is in your video. It sounds terrible, but it has been that way for quite some time and seems to be alright.

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    Quote Originally Posted by RyanW View Post
    I've noticed this noise is louder with a lighter flywheel. My Talon with a Fidanza flywheel is much louder than my VR-4 with an ACT chromoly flywheel. All sprung ACT2600 setups though. I always assumed it was the lighter flywheels not being able to dampen harmonics as well as a stock flywheel.
    +1!!
    Terry,
    91 AWD

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    I'm interested to see if the ATI damper helps with this. Noise is certainly a turn off for twin discs. But hey, it's a DSM, we should be used to strange noises!
    '14 Fiest ST Daily
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    I would give about 10:1 odds of the damper not making any noticeable difference in the noise level.
    Terry,
    91 AWD

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    Quote Originally Posted by Terry Livermore View Post
    I would give about 10:1 odds of the damper not making any noticeable difference in the noise level.
    +1

    Hal

  16. #16
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    If it's a lot heavier it might. oh and +1
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  17. #17
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    Put on light flywheel, get vibration
    Fix vibration with heavy damper

    What have we done here?
    The Internet: Where people who can't build sentences try to build cars.

  18. #18
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    Quote Originally Posted by Josh Warriner View Post
    Put on light flywheel, get vibration
    Fix vibration with heavy damper

    What have we done here?
    Reduced inertia....

    But I agree that the damper seems unlikely to solve your issue.
    -Charlie

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