Help identify this sound from my rear end

[QWK SVT]

The car's rear end, silly :D

Anyways, while at the track, I noticed a sound coming from the rear after spinning the tires (while the car is still pulling forward, by my foot has been removed from the gas pedal)... Sounds like a fan spinning, but no power being fed to it.

Here's what I hear:
http://www.qwksvt.com/Sharing/WindDown.mp3

I'm hoping it's nothing - the car launches and pulls well. No other sounds from the rear, under normal circumstances... Any guesses on what this is? :confused:

[MarauderMark]

Wow thats nuts but it sounds like transmission..unless maybe a bearing in the rear .But i what do i know.:dunno:

[Blackened300a]

UGH!!!

Thats the Sound of Money being Spent on something Expensive!!!
My Only Idea is that during the Burnout, You are putting A lot of Strain on the Posi-lock Clutches and when you let the torque off them, They are "FreeWheeling" cause the Torque was Removed so quickly. Just a Guess.

I replayed that over and over and Beisdes it sounding like a Door Hinge that needs oil, or my suggestion, Im Stumped :dunno:

[QWK SVT]

UGH!!!
Thats the Sound of Money being Spent on something Expensive!!!
I'm hoping this is wrong...



My Only Idea is that during the Burnout, You are putting A lot of Strain on the Posi-lock Clutches and when you let the torque off them, They are "FreeWheeling" cause the Torque was Removed so quickly. Just a Guess.

I replayed that over and over and Beisdes it sounding like a Door Hinge that needs oil, or my suggestion, Im Stumped :dunno:
I'm hoping you're right... I'm thinking the posi and wheels are spinning at the same rate, until I let off the gas. The tires are in the sticky stuff, so they slow pretty quick. I may have to try a burn out on the streets, to see if I can reproduce it there...

Like I said, there are no other signs of anything bad going on, but it's a little troublesome to hear this sound, as you're pulling up to the line:eek:

[LCSO34]

The exact same thing happened to me several weeks ago while i was bracket racing. After the burnout, I heard the noise, and looked down and relized I forgot to turn the OD off. I don't know if that had something to do with it but thats the only time I have heard it.

[Donny Carlson]

"Freeeet" = Cheesy Gordito Crunch from Taco Bell

"Pop....fee... pop!" = Cinema nachos

"Brraaaaappppsssslllllooopp" = Chili Cheese Footlong Hot Dog

[Joe Walsh]

"Freeeet" = Cheesy Gordito Crunch from Taco Bell

"Pop....fee... pop!" = Cinema nachos

"Brraaaaappppsssslllllooopp" = Chili Cheese Footlong Hot Dog


:lol: :lol:

PWWWAAAAHHHHHHHHHHHHH! = "My eyes are watering!"

Sorry.. :hijack:

[cyclone03]

I wish the clip was longer.
Does the clip start when you just lift after a stationary burn out,you know holding the brake with your left foot then rolling out?


Do you pull to the water box,hold the brakes get the tires spinning then let off the brake,staying in the throttle,letting the car roll, then let off the throttle and brake to a stop? If so the rear tires are spinning at about 80mph and what you are hearing is the rear tires braking to a stop.

Or,are you supercharged?Maybe it's the sound of an unloaded blower?

[grampaws]

I'm stumped,I haven't got a clue!!:(
Iwas thinking the crown gear in the diff the coast side
might have wear!!

[QWK SVT]

I wish the clip was longer.
Does the clip start when you just lift after a stationary burn out,you know holding the brake with your left foot then rolling out?


Do you pull to the water box,hold the brakes get the tires spinning then let off the brake,staying in the throttle,letting the car roll, then let off the throttle and brake to a stop? If so the rear tires are spinning at about 80mph and what you are hearing is the rear tires braking to a stop.
Sorry, that's the only clip I've got, right now.

What you've described is pretty much the exact scenario:

Tires spinning
Pull off brakes, still on gas pedal
Spinning while pulling forward
Let off gas still pulling forward
NOw I hear the sound (prior to braking to pull to staging lights)

The sound comes on, even though I'm creeping forward towards the staging lights, and depending how quickly I brake, almost seems to still be happening when stopped. It sounds like it's coming from the rear of the car and/or underneath, but to be honest it could be from anywhere. It does not appear to be tied to the speed of the tires (which I jumped to the conclusion it was the rear).

I've tried to duplicate it on the street, and the situation is the same. If I let go of the gas pedal while the wheels are still spinning, the same sound is heard. I'm wondering if it could even be the engine trying to slow down to match the rest of the driveline? This much is for sure, it's abviously something spinning, that is slowing down fast...

I'm completely at a loss, particularly since under all other circumstances the car feels/acts strong :confused:

[Blackened300a]

It sounds kinda like the Whine I have at higher speeds since I intalled the 4.10's. So Chances are, the Rear is where you will find where the noise is coming from.

[BillyGman]

That sounds like the noise that's common to a lot of Marauders, and used to be to mine also until the Trilogy S/Cer installation. Okay, so what's that have to do with a S/cer installation you say? On the Trilogy install the alternator is relocated, and turned around backwards with a special bracket that the kit comes with, but a special removal tool is also supplied with the kit. this special removel tool is used to remove the clutch mechanism from the stock Marauder alternator pulley.


While my car had that alternator clutch on the alternator pulley, I used to hear that noise right after letting off of the go pedal after stabbing it, and i could've sworn that it was coming from the transmision or something underneath the car, because that's what it sounded like. But it was just the way the acoustics of the engine compartment carried the noise inderneath the car. It was in fact my alternator pulley clutch, and it's normal. But as soon as I installed the S/Cer, it was no longer there. It's normal for Marauders. I drove my Marauder for about 5,000 miles before i ever noticed the noise, because it doesn't alwys occur.

Because of that clutch, you might also notice sometimes that your head lights dim during full throttle blasts, and you volt meter drops to below 12 volts for a couple seconds. That's common to many Marauders because of the alternator clutch.

[Bradley G]

I had the same noise too!

Seven Grands later, The noise is gone!:D

[AzMarauder]

UGH!!!

Thats the Sound of Money being Spent on something Expensive!!!
My Only Idea is that during the Burnout, You are putting A lot of Strain on the Posi-lock Clutches and when you let the torque off them, They are "FreeWheeling" cause the Torque was Removed so quickly. Just a Guess.

I replayed that over and over and Beisdes it sounding like a Door Hinge that needs oil, or my suggestion, Im Stumped :dunno:

I do not believe that clutches in the rear end "free wheel". The clutch pack is sandwiched and spring loaded. They apply torque to both wheels and slip when one wheel needs to turn faster than the other (going around a corner).

[AzMarauder]

I had the same noise too!

Seven Grands later, The noise is gone!:D
Ok... so are we saying that to get rid of this noise one installs a Trilogy Kit ? :P


Perhaps just getting rid of the alternator clutch would be a cheaper (but not horsepower producing) modification! :D

[grampaws]

Billy-g-mans suggestion about the Altenator clutch makes sense..

the alt would require a moment or two to wind down and if the
bearing/clutch has some wear /damage it would produce a similar
noise..and not being related to tire speed the diff is not likely
to be at fault..if the trilogy MM's eliminate the noise with a solid
pulley then this would reinforce this possability..
the old long screw driver/stethecope against the alt while revving th
eng should narrow it down...removing the pulley cover to check for
dirty grease comming from the pulley might be another indicator..

[BillyGman]

Ok... so are we saying that to get rid of this noise one installs a Trilogy Kit ? :P


Perhaps just getting rid of the alternator clutch would be a cheaper (but not horsepower producing) modification! :DLOL...yes, ofcourse we're talking about the alternator pulley clutch itself. ;) I was just explaining how it is that I know that the noise my car was making actually was in fact that same clutch. but it doesn't neccessarily have to be removed. It's just a harmless noise.

[QWK SVT]

[QUOTE=BillyGman]While my car had that alternator clutch on the alternator pulley, I used to hear that noise right after letting off of the go pedal after stabbing it, and i could've sworn that it was coming from the transmision or something underneath the car, because that's what it sounded like. But it was just the way the acoustics of the engine compartment carried the noise inderneath the car. It was in fact my alternator pulley clutch, and it's normal.QUOTE]

Futher testing reveals if I have the pedal mashed, and then completely let off while at higher rpm, I can hear it, as well. It's probably always been happening, but on the street I normally have a CD playing, and have only recently started playing with warming up the tires at the track.

Glad to hear that it's "normal" but I'm sure it still won't make me woarm and fuzzy, when I hear it :D Maybe I NEED a trilogy, to remove this sound... Think the g/f will buy that rationale? ;)

[grampaws]

Well I like your problem solving rationale!!:lol:

[Joe Walsh]

Because of that clutch, you might also notice sometimes that your head lights dim during full throttle blasts, and you volt meter drops to below 12 volts for a couple seconds. That's common to many Marauders because of the alternator clutch.

Billy, Not to Hijack this thread, and no flame intended, but the dimming of the lights at WOT is not because of the Alternator's mechanical clutch*, but due to the engine management system electrically shutting off the charging circuit.

* the alternator clutch is a mechanical one way clutch that allows the alternator to spin freely in reverse, that is why it can't be used on a reversed alternator mount Trilogy kit.
It keeps the serpentine belt from chirping on an upshift when the alternator is still spinning at 6100 rpm but the engine and serpentine belt have now suddenly slowed to @ 4500 rpm.

P.S. I does sound like the Trilogy kit solves a multitude of problems!!! :beer:

[BillyGman]

Billy, Not to Hijack this thread, and no flame intended, but the dimming of the lights at WOT is not because of the Alternator's mechanical clutch*, but due to the engine management system electrically shutting off the charging circuit.

No offense taken Joe, but I have to ask you that if what you're saying is true, then why is it that I no longer have the headlights diming at full throttle like I used to when the alternator pulley clutch was still on?

[Joe Walsh]

No offense taken Joe, but I have to ask you that if what you're saying is true, then why is it that I no longer have the headlights diming at full throttle like I used to when the alternator pulley clutch was still on?

Most of the S/C kits include a 'tune' which deletes this OEM electrical function. This is so that the fuel pump is ALWAYS supplied with full voltage, especially at WOT.
You don't want your fuel pump 'dimming' (browning out) at WOT on a S/C engine. :(

[Bradley G]

Glad to hear that it's "normal" but I'm sure it still won't make me woarm and fuzzy, when I hear it :D Maybe I NEED a trilogy, to remove this sound... Think the g/f will buy that rationale? ;)[Quote]
Want Warm and fuzzY?
stay With the G/F, want giggleing and goosebumps?
get a Trilogy! :P
I thought for sure something was wrong with the car , the first time I heard this noise.

[BillyGman]

Most of the S/C kits include a 'tune' which deletes this OEM electrical function. This is so that the fuel pump is ALWAYS supplied with full voltage, especially at WOT.
You don't want your fuel pump 'dimming' (browning out) at WOT on a S/C engine. :(That might answer my first question, but now I haveto also ask you another....if that's true, then how is it that I used to hear that noise upon lifting off of the throttle before the S/Cer installation, but for the past 17 months that I've driven the car since the S/Cer installation, I've never heard it again? that would be a pretty strong coincidence.

[David Morton]

* the alternator clutch is a mechanical one way clutch that allows the alternator to spin freely in reverse, that is why it can't be used on a reversed alternator mount Trilogy kit.
There's yer answer Billy. Yup, them thar alternators are like bi-sexual people, they'll charge in either direction. :lol:

[BillyGman]

There's yer answer Billy. Yup, them thar alternators are like bi-sexual people, they'll charge in either direction. :lol:But it still doesn't answer my other question.....if it was NOT the alternator pulley clutch that was making the noise in my car, then how can it be that I never hear that noise anymore now that the S/Cer has been installed on my car, and the alternator pulley clutch is gone?

[David Morton]

Go back and read these posts again Billy.

Noise = Alt clutch freewheeling. (your noise is gone now since you don't have one any more)

Headlights dimming = Factory tune turning off alternator electrically at the voltage regulator. (yours is now always on per Trilogy tune program)

The clutch is a purely mechanical device, a one way roller clutch that the computer does not control. If it had been left on your alternator it wouldn't spin the armature, since your alternator is now spinning in reverse.

(No that doesn't mean the headlights should shine black-light and the horn suck.) :lol:

The "strong coincidence" is in fact two separate things done with the Trilogy install, replacement of the clutch pulley and reprogramming of the computer to insure good voltage at WOT.

All clear?

Fire in the hole! :lol:

[BillyGman]

All clear?

Fire in the hole! :lol:LOL......okay Dave, I understand now. thanks for steering me straight on that. ;)

[David Morton]

My pleasure Billy. After all, talk's cheap.

Can you see that I am your friend? Do you know that I will always be your friend?

David, AKA- "Wind in his a$$" :lol: