Vibration between 50 & 70 mph

ABS550 said:

Did the frequency go up and down as you sped up and down? It should.
What is your gear ratio? Manual? Auto?

In my Manual GT with stock 3.31 gears and stock size tires at 110Kph (68Mph), the driveshaft turns at a CALCULATED speed of 47 times per second. (47 Hz) So my iPad hearing a very loud sound at 48Hz was close enough to know that they were a match.

In MY car 75 Mph would have given a sound of about 52Hz.

Do you have the auto with the 3.15 diff? That would explain why your frequency is different than mine. Of course, the phones/iPads could be a little off as well.
Sure looks like you are hearing the same thing I did.
Mine has been perfectly quiet since I did the DS balance last year.

Blake

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hlh1 said:

Is this just a sound analyzer app? What would this be called?

Mine goes into Ford on Monday. I have an Auto with 3.15 gears.

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codemanstang said:

yup. I got android go to the store i downloaded "Spectroid" it was free but there is many others. Just search sound analyzer. If you run this please post a screenshot while the noise is goin

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hlh1 said:

Is this just a sound analyzer app? What would this be called?

Mine goes into Ford on Monday. I have an Auto with 3.15 gears.

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codemanstang said:

Thanks for response man


Its auto with 3.15... At about 65 that frequency goes away, and it bounces around the 45-50mhz range. But its not as loud as that screen shot was. If i let the car sit IDLE i will see that same mhz as the peak audio frequency (though not as loud).

RPM dosnt make a difference, its dependent on speed only from what i notice.
I do have an H pipe (stock mufflers) and I only noticed this a few days after the H pipe was installed (unresonated) . I wonder if this could haven an effect?

Otherwise im Ford Racing stage 2 (tune / intake/throttle body) I wonder if the dealer would tell me to kick rocks on my warranty even though it was a CPO with 100k powertrain.


Ill have the car on all 4 jacks this weekend to paint the brake calipers. Ill check the exhaust for loose or anything else i should check for? i wonder if my exhaust goes at 47 and DS at 48 if it will give that womp womp womp noise. Sht idk lol

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hlh1 said:

I dropped my 17 off at Ford Service this morning. They gave me a loaner. I described how that it's really noticeable in the 55-60 mph range, especially when decelerating in neutral. Around town it's not too bad, but when spending hours on the freeway traveling it can get aggravating. Makes me not want to drive it on long trips. I gave them a copy of SSM 45938. Hoping for the best.

I LOVE the car otherwise.

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ABS550 said:

It is possible that what you are hearing is a droning sound from the exhaust. That happens, especially with aftermarket exhaust.
I also removed my resonator, but used an X-pipe in it's place. Stock mufflers. It makes no droning sound at all. I also have a Roush CAI.
The 48Hz sound I was hearing was on a bone-stock car, the first day I drove it home from the dealership! I cured it with a DS balance, before I changed anything on the car.
Generally an exhaust drone will occur in a certain RPM range. If you shift the transmission to 5th at 75Mph or even 4th, do you still hear the same sound?
If so, then it is likely your drivetrain and not your exhaust.
Remember, the driveshaft will always turn at the same RPM when you are at 75MPH, no matter what gear you are in. So if your DS makes a 47Hz sound because of an imbalance, then it will be there, regardless of what gear you are in.

You may need to return your car to stock for the dealership to troubleshoot this. Hard to say.
The more educated you on the topic before you talk to them, the better!


Blake

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codemanstang said:

yup had it in neutral. same soun betwwen 70-75mph

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codemanstang said:

Thanks for response man


Its auto with 3.15... At about 65 that frequency goes away, and it bounces around the 45-50mhz range. But its not as loud as that screen shot was. If i let the car sit IDLE i will see that same mhz as the peak audio frequency (though not as loud).

RPM dosnt make a difference, its dependent on speed only from what i notice.
I do have an H pipe (stock mufflers) and I only noticed this a few days after the H pipe was installed (unresonated) . I wonder if this could haven an effect?

Otherwise im Ford Racing stage 2 (tune / intake/throttle body) I wonder if the dealer would tell me to kick rocks on my warranty even though it was a CPO with 100k powertrain.


Ill have the car on all 4 jacks this weekend to paint the brake calipers. Ill check the exhaust for loose or anything else i should check for? i wonder if my exhaust goes at 47 and DS at 48 if it will give that womp womp womp noise. Sht idk lol

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Saber7 said:

Its not just the sound but the vibration. You can feel it overall case and point the rear view mirror is useless for a clear view its a blur from the vibration good luck to see if a Cop is behind ya

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