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bent fan blade #2389448
10/18/17 06:42 PM
10/18/17 06:42 PM
Joined: Oct 2004
Posts: 702
Oklahoma
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gregok Offline OP
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gregok  Offline OP
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Oklahoma
I have a seven blade fan for my mopar and it has one belt blade. Are those fixable or will it always be unbalanced? It is not bent too bad and could be put very close to its original position. I don't know how sensitive these fans are to not being exactly factory perfect. TIA

Re: bent fan blade [Re: gregok] #2389599
10/18/17 11:16 PM
10/18/17 11:16 PM
Joined: Mar 2008
Posts: 9,550
Sacramento CA
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Morty426 Offline
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Is it worth it? When fans it's not pretty and there is a lot of collateral damage.

Re: bent fan blade [Re: gregok] #2389654
10/19/17 12:45 AM
10/19/17 12:45 AM
Joined: Mar 2011
Posts: 1,653
Cut and Shoot, TX
kentj340 Offline
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Cut and Shoot, TX
I used to be a steel supplier to a large steel fan maker named Schwitzer in Rolla, MO, now closed due to the auto industry's switch to little pinto bean style front wheel drive cars with sideways engines and plastic fans.

In Schwitzer's conference room, there was a framed blueprint of a Model T fan that Schwitzer once made. I remember passing by the Chrysler St Louis assembly plant each time I drove to Rolla.

Fan BLADES for manly V8 rear wheel drive cars were made of ordinary quality cold rolled steel that had been annealed or softened following cold rolling which work hardens it. A slightly bent and straightened blade should present no problem if it was slightly bent once and straightened once. Work hardening and brittleness could happen if a blade were bent and straightened many times in the same place, just like bending a coat hanger many times in the same place will eventually break.

The fan HUB, the thicker material in the center to which the blades are riveted, is the most critical part. This part is made of special fatigue resistant quality steel, as the hub is subject to deformation in use. That is, the pitch that each spoke of the hub is bent to will tend to unbend from high speed wind resistance, then spring back at slower speeds. Since this is fatigue resistant steel (meaning resistant to work hardening), bending and straightening once or a few times should not cause any work hardening or embrittlement. FWIW, fan hubs were made of exactly the same fatigue resistant quality of steel as steel wheels, which take a lot of deformation in cornering, the reason hub caps are most often lost at corners. The constant deformation of steel wheels in use is sometimes the cause of cracking in the hub-to-rim weld, creating an air leak. This happened to me once.

If it were my car, I would straighten the blade and not worry about it. But I would never stand beside any fast running fan in any case, bent or never bent.

By the way, as OEM steel fan hubs were made of special quality steel, I would never trust that any aftermarket steel fan hub is made of the same.


If you don't see two dolphins, you need a vacation.
Re: bent fan blade [Re: kentj340] #2389673
10/19/17 01:26 AM
10/19/17 01:26 AM
Joined: Oct 2004
Posts: 702
Oklahoma
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gregok Offline OP
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Thanks for the great info.

Re: bent fan blade [Re: gregok] #2389694
10/19/17 03:22 AM
10/19/17 03:22 AM
Joined: Mar 2011
Posts: 1,653
Cut and Shoot, TX
kentj340 Offline
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Cut and Shoot, TX
Look closely on your fan, and you might find "Schwitzer" embossed somewhere in tiny letters. I found that once on a GM fan. Not sure if Schwitzer supplied to Chrysler or if Chrysler made their own.

An interesting thing to notice about steel fans: the blades are unevenly spaced for noise cancellation. So you could say they were maybe a bit unbalanced when new. AFAIK there was no balancing operation as a part of fan manufacture, unless you can find evidence of adding or subtracting weights.


If you don't see two dolphins, you need a vacation.
Re: bent fan blade [Re: gregok] #2389755
10/19/17 11:36 AM
10/19/17 11:36 AM
Joined: Jan 2011
Posts: 499
Brownstown, PA
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FJR doc Offline
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Brownstown, PA
Thanks for the great info kent.


Follow my Duster 340 restoration progress on FABO http://www.forabodiesonly.com/mopar/showthread.php?t=225784

Kevin
Re: bent fan blade [Re: kentj340] #2389838
10/19/17 02:26 PM
10/19/17 02:26 PM
Joined: Dec 2003
Posts: 3,519
Lansing, MI
70gtx440dana Offline
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Lansing, MI
Originally Posted By kentj340
Look closely on your fan, and you might find "Schwitzer" embossed somewhere in tiny letters. I found that once on a GM fan. Not sure if Schwitzer supplied to Chrysler or if Chrysler made their own.

An interesting thing to notice about steel fans: the blades are unevenly spaced for noise cancellation. So you could say they were maybe a bit unbalanced when new. AFAIK there was no balancing operation as a part of fan manufacture, unless you can find evidence of adding or subtracting weights.



They are balanced regardless of even or uneven spacing. Look closely at the construction and you will see that there are design features that allow for the balancing on uneven blade designs.

Last edited by 70gtx440dana; 10/19/17 02:28 PM.

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Re: bent fan blade [Re: 70gtx440dana] #2389839
10/19/17 02:30 PM
10/19/17 02:30 PM
Joined: Dec 2007
Posts: 18,157
Mass
DAYCLONA Offline
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DAYCLONA  Offline
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Mass
Originally Posted By 70gtx440dana



They are balanced regardless of even or uneven spacing. Look closely at the construction in you will see.



Agreed on the balancing, as far as the OP "repairing" the fan, I've bent back to shape many 4,5,7 blade fans over the decades with ZERO issues

Re: bent fan blade [Re: gregok] #2389976
10/19/17 07:27 PM
10/19/17 07:27 PM
Joined: Oct 2004
Posts: 702
Oklahoma
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gregok Offline OP
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Oklahoma
Alrighty then. I will bend it carefully back and see what happens. Thanks to everyone for their comments.







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