Flex Fans Good and Bad

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mguner

mguner

How many is too many?
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After seeing members and friends being seriously injured and stories of fatalities I hope to clarify which Flex Fans are the culprits of infamy and which are a good product.

Any metal flex fan has the potential for fatigue, cracking and rivet separation. Any fiberglass flex fan which has multiple pieces riveted together is also a ticking time bomb.

fan20.jpg


These type (below) I have never seen fail from anything other than impact.... Provided they stay below their designed RPM limits.

flx-415_w.jpg
 
what do you make of the stocker on my duster ?
(think it came from a mobile home)

it has a metal frame, rubber blades with metal trim on the outside edge
 
I seen one of the blades in the top picture come apart and shot threw a fiber glass chebby truck hood.
 
I wouldn't trust a flex fan of any kind. Stick with the Mopar viscous fan.
 
diymirage said:
what do you make of the stocker on my duster ?
(think it came from a mobile home)

it has a metal frame, rubber blades with metal trim on the outside edge
Click to expand...

Anything with multiple pieces is a NO in my book for high RPM and performance applications. I have a nice factory MOPAR steel flex type unit that I refuse to put on anything as I have seen the same fans with cracks forming in the blade roots and others in pieces in the junk yard.
 
jboyd2 said:
You need to read this thread:
http://www.forabodiesonly.com/mopar/showthread.php?t=347235
Click to expand...

That is why I started this thread....

The choice of pulleys is often overlooked when these fans fail. Many stock applications especially with A/C had large crank pulleys and small water pump pulleys thus easily exceeding the RPM rating for some aftermarket fans. All of my race car applications have run the small crank pulley which means even the engine I revved to 8500 would not have exceeded the 8000 RPM limit of the nylon Flex-a-lite had that car even been using a fan.
 
I am guilty to have the joy in owning the first one,brute ll. never again,i was stupid being 18 at the time.
 
I was installing a blue Flex-a-lite just like the one pictured. I should have had gloves on but my wrench slipped and the hand that was holding the blade needed 6 stitches to stop the bleeding. I vote with Rusty.
 
makes you wonder when the manufacturers guarantee some
them safe to certain rpm's.
I would have some concern about that old beat up unit you found
at a flea market,but you would probably be o.k. with a good quality
new one.
 
BTW, the RPM ratings are not guarantees: they are ratings.

I've had 3 stainless flex fans and both suffered cracked blades after a while; they crack at the side of the blade just outside of where they are clamped under the riveted holder. This is where the flexing concentrates so that is not surprising. I never had any issues with a multi-piece fiberglass bladed flex fan.

I've raced thousands of rally stage miles on stock type, molded nylon fans with 1:1 pulley setups and revving all the time to 7500-8000 RPM, with a 3800 RPM minimum (wild cam!). Never a hint of failure. So I'm with Mguner on using a 1 piece MOLDED flex fans being OK.
 
nm9stheham said:
BTW, the RPM ratings are not guarantees: they are ratings.

I've had 3 stainless flex fans and both suffered cracked blades after a while; they crack at the side of the blade just outside of where they are clamped under the riveted holder. This is where the flexing concentrates so that is not surprising. I never had any issues with a multi-piece fiberglass bladed flex fan.

I've raced thousands of rally stage miles on stock type, molded nylon fans with 1:1 pulley setups and revving all the time to 7500-8000 RPM, with a 3800 RPM minimum (wild cam!). Never a hint of failure. So I'm with Mguner on using a 1 piece MOLDED flex fans being OK.
Click to expand...

I by no means would lean over the molded units while revving the engine and if someone has had an experience of a molded fan coming apart I would like to hear about it. I'm just saying they are a much safer and reliable unit than the Ginsu type.
 
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