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Harmonic vibration at hwy speeds in 97 Ford Explorer

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  #1  
Unread 11-06-2013, 12:17 PM
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Harmonic vibration at hwy speeds in 97 Ford Explorer

I realize this may be a bit off the topic of long range hunting, but I do use this rig to hunt, so there is a connection and I have a feeling there's a few guys hanging out here that might have some ideas if they are willing to take a stab at it. Len, delete this if it's out of line.

I've got a 1997 Explorer 4WD with a harmonic vibration that starts at 65mph and goes up as far as I've taken it. Typically at hwy speedds, it lasts for about 5 seconds then goes away for 3-4 seconds, then comes back in that cyclical fashion. I can feel it in the seat and some in the steering wheel, but I think that's (steering wheel) just because it's strong enough to feel it in the entire car.

I did not recall noticing this until I purchased new Toyo Open Country 6 ply A/T tires last fall after blowing one of the same tires (about at the end of their life) on a trip that entailed 200 miles of nasty gravel roads on northern Vancouver Island. There were just a few feet on the aluminum rim til I stopped. Les Schwab has checked and double checked the rims alone. The other day (their suggestion, not mine) they gave me a complete set of new tires as they had found a little treadwell seperation in on the year old tires and the vibration was less, but still there.

I recently had the upper control arms replace and had a new C/V joint replaced. Front sway bar bushings are just about 2 years old. 2 garages say there is nothing wrong with the front end or wheel bearings etc. Lower ball joints are new 2-3 years ago. It's been aligned 3x over the past year.

This happens at a certain speed (65mph and above) over the ground so it's got to be txfer case output shaft or back from that. Local Ford garage said that the txfer case output shaft is good and tight. U-joints all check out good. Driveshaft out of balance? Something in the rear diff?
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  •   #2  
    Unread 11-06-2013, 02:27 PM
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    Re: Harmonic vibration at hwy speeds in 97 Ford Explorer

    Hey, I'm all over this one!!

    This is evidence a cyclic resonance harmonic vibration between two vehicle components.

    They had a similar problem with the F-32 fighter. Their problem was when both engines were at the exact RPM there was no vibration. However when one or the other of the engines oscillated in RPM, which one usually did, the vibration would occur. Thus vibration, no vibration then vibration over and over again until they dropped below Mach I.

    Your solution would be to weld the rear differential so that both wheels on always rotated at the same exact RPM.

    If you buy into this you're as goofy as me.

    Oh, I just dreamed up that F-32 stuff too.

    However, I would give rotating those tires around and see what happens.

    Those kinds of things drive a fella nuts.

    I have a "click" showing up in the left front of my 01 Chev 1500. The farther away from home the more I think about it.

    Keep lookin' you'll find it....

    Cheers

    Roy
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      #3  
    Unread 11-06-2013, 02:41 PM
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    Re: Harmonic vibration at hwy speeds in 97 Ford Explorer

    The click is because it's a Chevy. Thats Obama rattling around under the hubcap.

    It's the agressive tread pattern setting up the vibration. Swotch to a rib tread tire and it will disappear.

    I run 31 x 10.5 x 16's on my F350 4x4 in Goodyear All Terrain KO/KD's and the tread design (agressive) causes some vibration, I ignore it.
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      #4  
    Unread 11-06-2013, 05:14 PM
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    Re: Harmonic vibration at hwy speeds in 97 Ford Explorer

    I'm with Roy, when you start forgetting things, don't get stressed just start remembering it wrong. Way more fun any way.

    I've had a driveline give similar grief, but I think Sidecar, might have it pegged with the tire tread. Or it's a little of this and that, that's going to be a bitch to solve.
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      #5  
    Unread 11-06-2013, 05:20 PM
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    Re: Harmonic vibration at hwy speeds in 97 Ford Explorer

    Turn the radio up!
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      #6  
    Unread 11-06-2013, 05:25 PM
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    Re: Harmonic vibration at hwy speeds in 97 Ford Explorer

    And here I thought I'd get experts to pinpoint the problem! What was I thinking?

    Yeah, roy, running two engines at once whether in a plane or boat, there is definitely a sweet spot you can hear!
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    "And can the liberties of a nation be thought secure when we have removed their only firm basis, a conviction in the minds of the people that these liberties are the gift of God?" Thomas Jefferson - Notes on the State of Virginia

    www.wildsidesystems.com - Shelter for Your WildSide - http://www.youtube.com/watch?v=tYwgo...&feature=g-upl
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      #7  
    Unread 11-06-2013, 07:41 PM
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    Re: Harmonic vibration at hwy speeds in 97 Ford Explorer

    Quote:
    Originally Posted by bigngreen View Post
    Turn the radio up!
    That's funny right there, I don't care who you are
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