"Harmonic Vibration"
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"Harmonic Vibration"
" 79 302, C-4: had trans. rebuilt 2 years ago and ever since I have had this "Harmonic Vibration" which my trans. man tried to correct by swapping out the torque converter twice to no avail. so I've lived with it... now it seems to be getting worse, and I've been advised that they might have either put the wrong flywheel on or the rebuilt torque converter is unbalanced or defective in some way, I've also been advised that "Truck" 302s are balanced differently than "Car" applications, I've been around Fords for many years and have never heard this before, what do YOU think??? Thanks, Rick
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Joined: May 1999
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"Harmonic Vibration"
I drive a tracktor-trailer and I have seen the fly wheel bend or warp, but that is on a big truck and you could get vibration. Remember it is all tied in together so it might feel like it is coming from the trans. I have also heard of the harmonic balancer get out of wack and vibrate the whole truck. maybe check the drive shaft balance to. Does it happen all the time or low speeds or high speeds
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"Harmonic Vibration"
Rick, I had a '67 Ford SW with a 289 and C4. If memory serves me it had a vibration damper affixed to the tail housing. I have seen some trannys with this and some without. Might be yours is missing.
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"Harmonic Vibration"
Since you are running a C-4, your flex plate is the primary source for engine balancing. The harmonic balancer is somewhat of a misnomer, primary function really lies in engine timing. It is hard to believe that the trans shop would not have checked for the counter-weight on the flex plate. But you can check yourself by removing the inspection plate and hand rotating the engine; make sure that all of the weight is there. Did you happen to change flex-plates? Ford changed the exterior balancing in 302s but the plates will interchange. Or did some idiot screw around with the bolt pattern to make it fit? They only go on one way. And look at the harmonic balancer/timing guage. That rubber insert dries out and they can slip around. I have a 67 289 right now that is off some 150 degrees; great for timing an engine!
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