I have asked many people this question and none seems to know the answer! Why are the fan blades on my 67' L79 not evenly located on the fan hub?? Thanks Mike #34566
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Re: Why out of balance fan blades??
This is probably not THE reason, but the bolts would be very difficult to remove were it not for the extra "space" between the blades. Probably an issue of dynamic balance vs static balance. I'm sure the dynamic balance is there, otherwise you would have lots of problems. -
Re: Why out of balance fan blades??
This is probably not THE reason, but the bolts would be very difficult to remove were it not for the extra "space" between the blades. Probably an issue of dynamic balance vs static balance. I'm sure the dynamic balance is there, otherwise you would have lots of problems.Comment
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Re: Why out of balance fan blades??
Mike-----
I believe that the reason for the non-symetrical arrangement of the fan blades is noise reduction.In Appreciation of John HinckleyComment
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Re: Why out of balance fan blades??
Mike-----
I believe that the reason for the non-symetrical arrangement of the fan blades is noise reduction.In Appreciation of John HinckleyComment
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Re: Why out of balance fan blades??
It's an acoustic issue. The uneven spacing prevents acoustic resonance that could cause objectionable noise at certain speeds if the blades were spaced evenly.
For the same reason the length/spacing of tire tread blocks varies around the circumference of a tire. If not, a tire can cause a significant noise at certain speeds.
DukeComment
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Re: Why out of balance fan blades??
It's an acoustic issue. The uneven spacing prevents acoustic resonance that could cause objectionable noise at certain speeds if the blades were spaced evenly.
For the same reason the length/spacing of tire tread blocks varies around the circumference of a tire. If not, a tire can cause a significant noise at certain speeds.
DukeComment
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Yes!
To both Duke and Joe. Intentional offset of 5-blade fan is to thwart whine (break up higher order harmonics).
Next, your fan should NOT be out of balance. There's two forms of balance axial and radial. Axial imbalance happens when a given blade or its mounting spider is bent out of true (flat circular rotation plane).
Depending on the year of the car, radial balance was achieved in one of two ways: later car/fan assy's had 'pop rivet' weights attached to certain blades to achieve rotational balance. Early fans were balanced by selectively t******* material off the end of one or more blade(s)which is why those who 'cheat' and take a larger passenger car 5-blade fan and blindly cut material off the end of each blade can wind up seeing water pump bearings live a short life....Comment
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Yes!
To both Duke and Joe. Intentional offset of 5-blade fan is to thwart whine (break up higher order harmonics).
Next, your fan should NOT be out of balance. There's two forms of balance axial and radial. Axial imbalance happens when a given blade or its mounting spider is bent out of true (flat circular rotation plane).
Depending on the year of the car, radial balance was achieved in one of two ways: later car/fan assy's had 'pop rivet' weights attached to certain blades to achieve rotational balance. Early fans were balanced by selectively t******* material off the end of one or more blade(s)which is why those who 'cheat' and take a larger passenger car 5-blade fan and blindly cut material off the end of each blade can wind up seeing water pump bearings live a short life....Comment
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Re: Yes!
Thanks Guys !! I love this web site , no matter how bizarre the question someone has the answer!!! mikeComment
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Re: Yes!
Thanks Guys !! I love this web site , no matter how bizarre the question someone has the answer!!! mikeComment
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