# Hush hush noise



## Pierre spiteri (Apr 13, 2009)

i would like to share my little problem. I have an 11 inch general electric dc motor in my car. When i drive the car in my garage or in a quiet rode i hear a sort of hush hush noise then when i accelerate it fades away. I tried to work the motor alone without engaging the gearbox and the noise wasnt there. What could it be? Its only heared when i take off from a standstill.


thanks for your help


Pierre Spiteri


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## dedlast (Aug 17, 2013)

Pierre spiteri said:


> i would like to share my little problem. I have an 11 inch general electric dc motor in my car. When i drive the car in my garage or in a quiet rode i hear a sort of hush hush noise then when i accelerate it fades away. I tried to work the motor alone without engaging the gearbox and the noise wasnt there. What could it be? Its only heared when i take off from a standstill.
> 
> 
> thanks for your help
> ...



Does the sound speed up that faster you drive? If so, it could be that it isn't fading out, it's just reaching a frequency that blends in with the rest of the noises in the car.
You say you don't hear it with just the motor so that leads me to believe it is somewhere in the rest of the driveline. 
If you would list the year/make/model of the car, there may be someone who could give you a knowledgeable answer.
In the meantime, you could have a brake shoe dragging, you could have something in a tire tread, you could have bearing going out...

Bill


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## Pierre spiteri (Apr 13, 2009)

the car is a peugeot 106 . If it was break shoe t would heat up i think.]thanks fro your help

Pierre


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## dragonsgate (May 19, 2012)

Find a hill with a relatively smooth road and coast down in neutral. If you hear the noise it could be a warped disc. wheel bearings something rubbing somewhere. Coast in different gears. If you have a clutch it might be the throughout bearing adjusted to tight. Bill beat me to this so I am just repeating pretty much what he says.


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## dragonsgate (May 19, 2012)

Pierre spiteri said:


> the car is a peugeot 106 . If it was break shoe t would heat up i think.]thanks fro your help
> 
> Pierre


 never mind


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## Pierre spiteri (Apr 13, 2009)

hi again i did drive it up a hill and it does that noise in all gears as it takes off, the car is a clutch less manual. when it coasts it makes no noise.


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## dragonsgate (May 19, 2012)

Pierre spiteri said:


> the car is a peugeot 106 . If it was break shoe t would heat up i think.]thanks fro your help
> 
> Pierre


I do have dyslexia and I glanced at this message quickly which I should never do. I misunderstood it to say you found the problem. What ever your problem is, it is catching and getting worse because coming home from my mail run an hour ago I heard a growling noise in my car. You say you drove up hill. Did you coast down in neutral and various gears? The noise happens only when you take off? Maybe you could put the car on blocks with the tires off the ground and with the wheels locked step on the throttle to see if you can duplicate the sound. Hold the throttle down for only a split second with the wheels locked up as it is not good to stall the motor. Anyhow you could have a helper try to find where the noise is coming from. Check for loose cable that might be arcing.


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## TEV (Nov 25, 2011)

dragonsgate said:


> What ever your problem is, it is catching and getting worse because coming home from my mail run an hour ago I heard a growling noise in my car.


LOL, I just changed a front wheel bearing last Friday, and until it got very bad I was thinking that something was happening with my adapter or gear box .


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## Pierre spiteri (Apr 13, 2009)

i coasted the car using several gears and there is no noise. I also put the handbrake on to make the motor pull harder ( similar to what you told me to lock the wheels but there was no noise). The noise only happens when i floor it and while the motor is giving all its torque ther is a slight noise , not that much and it happens in all the gears. While at constant speed it makes no noise at all. The cables are ok. There is no growling noise and it is heard when i am driving in a silent space such as a garage or at night.


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## dragonsgate (May 19, 2012)

Pierre spiteri said:


> The noise only happens when i floor it and while the motor is giving all its torque ther is a slight noise , not that much and it happens in all the gears. While at constant speed it makes no noise at all.


 Power cables will actually move when a heavy load is placed on them. Kind of like a garden hose filling with water.When you drop the hammer all the juice is trying to get through at once so you might be hearing the electricity coursing through the cables and electrical components. I don't think there is anything to worry about.


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## dragonsgate (May 19, 2012)

Pierre spiteri said:


> The noise only happens when i floor it and while the motor is giving all its torque ther is a slight noise , There is no growling noise and it is heard when i am driving in a silent space such as a garage or at night.


That is confusing. You say it only makes noise at full throttle but you hear it in your garage. If I gave full throttle in my garage I would crash through the door go up the stairs and into the living room.


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## Pierre spiteri (Apr 13, 2009)

let me try to explain a bit better, sorry for the misunderstanding. I hear the hush noise when i floor it or when i drive it slowly in my garage. My car is only a 48v system. When i reverse it does hush a bit but it has to be quiet place to be heard. When i drive in a normal smooth road there is no noise. When i work the motor in neutral there is no noise. Could it be the gearbox while under strain to make the noise becasue when the speed is constant there is no noise.


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## dragonsgate (May 19, 2012)

A 48 volt system is going to use a good amount of amps to get 2,000 pounds moving so you probably have to mash the peddle down pretty far to get going. When you get moving things ease off a little. I think you are hearing the electrical components hum on takeoff.


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## Pierre spiteri (Apr 13, 2009)

it may be true, i will try to look in to it. thanks a lot


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## TEV (Nov 25, 2011)

If your car is rear wheel drive and have a drive shaft, it may be a bad universal joint.


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## PStechPaul (May 1, 2012)

Another possibility is a shift in the motor alignment under heavy torque, especially if the motor mounts are not rigid enough.

Can you capture the sound by using a video camera or phone?


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## azdeltawye (Dec 30, 2008)

Pierre spiteri said:


> .... When i drive the car in my garage or in a quiet rode i hear a sort of hush hush noise....
> 
> Pierre Spiteri


Maybe you forgot to turn down the volume on that Deep Purple CD you have in the player..


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## Pierre spiteri (Apr 13, 2009)

i am now driving the car every day. Last night there was this hush hush noise when i get going from stand still. This morning not a single noise. Would it be possible that the bearings could occasionally hum and be heard because the car is silent and in a normal car with ice engine they wouldn't because of the running engine?


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## dragonsgate (May 19, 2012)

Pierre spiteri said:


> i am now driving the car every day. Last night there was this hush hush noise when i get going from stand still. This morning not a single noise. Would it be possible that the bearings could occasionally hum and be heard because the car is silent and in a normal car with ice engine they wouldn't because of the running engine?


What kind of car is it? what year? Does it have a clutch? You need to pinpoint where the noise is coming from and go from there.


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## dtbaker (Jan 5, 2008)

Pierre spiteri said:


> i would like to share my little problem. I have an 11 inch general electric dc motor in my car. When i drive the car in my garage or in a quiet rode i hear a sort of hush hush noise then when i accelerate it fades away.i



my guess would be the limited slip rear diff. Some are fluid coupled, and under heavy accel they make a really weird noise until the torque lets up.


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## Pierre spiteri (Apr 13, 2009)

I went to my mechanic he told me its the coupling which is making the hush noise and toold me not to worry . What is your opinion? As usual the slight hush noise goes away immmediately after i accelerate


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## Pierre spiteri (Apr 13, 2009)

I went to my mechanic he told me its the coupling which is making the hush noise and toold me not to worry . What is your opinion? As usual the slight hush noise goes away immmediately after i accelerate


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## sabahtom (Mar 1, 2011)

*Power cables moving?*



dragonsgate said:


> Power cables will actually move when a heavy load is placed on them. Kind of like a garden hose filling with water.When you drop the hammer all the juice is trying to get through at once so you might be hearing the electricity coursing through the cables and electrical components. I don't think there is anything to worry about.


That sounds interesting. Any idea of a link that I can go to for more on why cables would do that?


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## TEV (Nov 25, 2011)

*Re: Power cables moving?*



sabahtom said:


> That sounds interesting. Any idea of a link that I can go to for more on why cables would do that?


Very nice Tom. Are you a diplomat too ?


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## dragonsgate (May 19, 2012)

*Re: Power cables moving?*

_Power cables will actually move when a heavy load is placed on them. [That sounds interesting. Any idea of a link that I can go to for more on why cables would do that?]_


TEV said:


> Very nice Tom. Are you a diplomat too ?


Ok I should have known better than make that statement but I know what I saw.


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## RIPPERTON (Jan 26, 2010)

Pierre spiteri said:


> The noise only happens when i floor it.


Some part of the drive train flexing like disc rubbing on a pad.
Try backing the pads away from the discs then short test drive without putting your foot on the brake


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## PStechPaul (May 1, 2012)

It is a well-known fact that cables carrying heavy current will move or exert forces on each other. This is the Lorentz force, and along with Faraday's Law it shows that conductors with current flowing in the same direction will pull closer to each other, while a loop with current flowing in opposite directions will tend to push the cables apart. This is why cables should be tightly bundled together and secured to the chassis so they will not move and interfere with moving parts, or damage the insulation. Here is a demonstration at about 850 amps:





 
If there is any ferrous material within the loop, it will be magnetized and will experience strong forces. It can be powerful enough to send a wrench flying. These basic principles are what explain the operation of electric motors and contactors. And it also explains the concept of "skin effect", where current tends to concentrate near the surface of conductors, mostly at higher frequencies.


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## dragonsgate (May 19, 2012)

PStechPaul said:


> It is a well-known fact that cables carrying heavy current will move or exert forces on each other. This is the Lorentz force, and along with Faraday's Law it shows that conductors with current flowing in the same direction will pull closer to each other, while a loop with current flowing in opposite directions will tend to push the cables apart. This is why cables should be tightly bundled together and secured to the chassis so they will not move and interfere with moving parts, or damage the insulation. Here is a demonstration at about 850 amps:
> 
> 
> 
> ...


Thank you Paul.


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## sabahtom (Mar 1, 2011)

*for the record*

Just to clarify, I wasn't being sarcastic there. I did Lorentz in high school but it sounded like Dragonsgate was describing something different.


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## dragonsgate (May 19, 2012)

*Re: for the record*



sabahtom said:


> Just to clarify, I wasn't being sarcastic there. I did Lorentz in high school but it sounded like Dragonsgate was describing something different.


 Don't sweat it Sabahtom.
I don’t want to get to far off Pierre’s topic but for all I know I might have been talking about something different. I remember seeing the cables move and a sound. It was longer than yesterday so I can’t remember any more details. It doesn’t take much for me to get in over my head. I might as well be talking about UFO’s. Any way back to the hush hush sound. Pierre says it happens when accelerating or taking off. Has to be something that goes round moving laterally lightly rubbing against another part. If it is the coupler then I would be concerned.


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