2002 Ford F250 Vibration at 70 mph

2002 FORD F-250
240,000 MILES • V8 • 4WD • AUTOMATIC
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FISHINGFOOL227
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My truck has had a relatively high frequency vibration since approx, 70k miles. It becomes noticible at approx 70mph, and at 73mph, there is a mild rumble.
The tires have been balanced while on the truck. The drive shaft has been checked and it is in balance.
If I hit 70-75mph going downhill, and I shift to neutral, the vibration and rumble remain which leads me to believe that it is not related in any way to the engine/flywheel.

Any thoughts???
Do you know of a mechanic in Southern Calif. w/ an Electronic Vibration Analyzer?
Aug 26, 2010 at 11:24 PM
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BLACKOP555
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you sound like you know what your doing since putting it in neutral it elimates a issue with the vehicle's engine causing it.

next thing do a heavy acceleration and let me know what rpms if any that the vibration comes on at then do a light accel. i dont know anyone with a eva in so cal but ill as around
Aug 26, 2010 at 11:55 PM
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FISHINGFOOL227
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Thank you blacktop...

It is not RPM related, it is speed related. Happens at exactly 72mph no matter the RPM's. It may just be coincidence, but I just found that my right front hub is bad. I'm having it replaced tomorrow. I found this out when my 4 x 4 would not engage. I'm wondering if the damaged hub could be causing the vibration/rumble???
Aug 30, 2010 at 11:35 PM
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FISHINGFOOL227
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Hi...

I'd really like to get the vibration/rumble fixed. I read somewhere that an EVA (Electronic Vibration Analyzer) can essentially pinpoint the source of the vibration by measuring both the frequency and the amplitude of the vibration. Since the various possible sources of the vibration each have a characteristic rotational speed, it actually becomes a math question.

Do you know of anyone in Southern California who has an EVA?

I'm leaning towards the rear differential as the culprit. If the ring and pinion gears are not at their proper angle, I believe that you can get a "backlash". Could this cause a vibration and rumble?
Sep 17, 2010 at 11:09 PM
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BLACKOP555
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if the driveshaft is slightly misbalanced it can cause this issue. does the vibration go away when vehicle is put in neutral? how about downshifiting?

try messaging 2carpros jack. he would be the only one that may have it. the EVA is nice. has an option to ballance the driveshaft with just 2 hose clamps for a temporary fix.

your bearing going out can cause a vibration. do you feel the vibration more in seat or in the steering wheel. seat suspect rear end and driveshaft. steering wheel bearings and tires.
Sep 27, 2010 at 5:05 PM