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Author
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Topic: Strange Vibration
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jay67fast
Gearhead Posts: 146
From: Boca Raton, Florida,U.S.A.
Registered: Nov 2004
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posted 05-29-2006 07:20 PM
 
The best way I can explain my problem is ----I feel a vibration in the car at all speeds, but it comes and goes; that is, it's almost a harmonic vibration. If you would draw a sine curve on a piece of paper, and label the low spots on the sine wave as "no vibration" and the high spots on the sine waveas "vibration" and then read them left to right, I think you'll see what I mean-- in addition, sometimes these vibrations are almost entirely gone and other times they are more pronounced. It's not a violent vibration, I can feel it in the wheel, and the inside rear view mirror image jumps slightly, but you can't feel it in in your body through the seats, and no passenger has ever noticed it.
But it's definitely there, and I'm afraid of what just letting it go might do. I worry about something out of balance might be tearing up bushings or bearings or seals somewhere in the drivetrain. Have any of you guys any idea of what it might be, or how to diagnose the problem? If I build up some speed and shift into neutral, it SEEMS to go away, but I wouldn't bet my life on that. Any ideas?
Thanks in advance,
Jay67fast
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Fastymz
Moderator Posts: 22791
From: Reno Nv M&M #1240
Registered: Apr 2001
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posted 05-29-2006 08:02 PM
Jay, If it's in the steering wheel then it's coming from the front end. If you run the same size tires all around. Rotate a the fronts to the rear and see if that helps?------------------
oddly obsessed with big scoops on little Mustangs HOOD HACKERS DELIGHT!
My Pics I haven't failed. I've just found 10,000 ways that won't work.
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jay67fast
Gearhead Posts: 146
From: Boca Raton, Florida,U.S.A.
Registered: Nov 2004
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posted 05-29-2006 09:23 PM
Fastymz,
Thanks for the hint. That sounds like a great idea, very logical!! I'll try that tomorrow. Will keep you posted.
Yjanks again,
Jay67fast
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RonnieT
Gearhead Posts: 912
From: Port Allen, La. 70767
Registered: Jun 99
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posted 05-30-2006 12:01 AM
quote:
Originally posted by Fastymz:
Jay, If it's in the steering wheel then it's coming from the front end. If you run the same size tires all around. Rotate a the fronts to the rear and see if that helps?
Not always true. Since the steering column is mounted solid to the dash it will pick up vibration from any source. My wifes car had a vibration you could feel in the steering wheel and after the shop replaced both CV shafts, front wheel bearings, and misc other parts in the front end they found it was a bad rear wheel bearing. Good thing it was after and accident and the insurance company was paying for everything. ------------------
Ronnie
69 mach1 351W-4V engineless at the time!
70 Torino GT 351C-4v with a "shaker"
Mustangs and More Member #23
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indyphil
Gearhead Posts: 3394
From: Senoia, G.A. USA
Registered: Jul 2002
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posted 05-30-2006 11:07 AM
those harmonics as you describe them tend to mean that you may have two rotating components that when they are in phase will cancel each other, and when they are out of phase will combine. If one rotates a little tiny bit slower than the other then you get that effect as they go in and out of phase with each other. Twin prop airplanes often have synchronising mechanisms so that you can synchronise the props to avoid the vibration.In your case I bet you have a wheel balance issue. depending on exact diameters (which vary based on PSI) your tires can spin at slightly different RPMS, and if they are not well balanced your symptoms could occur. Check air pressures and try to balance them out (or just change the pressures) if the vibrations change in frequency (because the relative RPMs have changed) then you can focus in on the problem. Getting tires balanced is cheap and might be a good first step. ------------------
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Jake11
Gearhead Posts: 246
From: Banning,Ca,USA
Registered: Oct 2005
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posted 05-30-2006 08:22 PM
Ck. your U-joints.
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