Fan Torque

sconnors

sconnors

Well-known member
Howdy fellas,
I am putting a 2 blade aluminum fan on at the suggestion of everyone here, and wonder if there is a certain amount of ft/lbs. of torque I should use or just tighten it good?
Any input would be greatly appreciated.
Thanks
Scott
 
sconnors said:
Howdy fellas,
I am putting a 2 blade aluminum fan on at the suggestion of everyone here, and wonder if there is a certain amount of ft/lbs. of torque I should use or just tighten it good?
Any input would be greatly appreciated.
Thanks
Scott
Click to expand...
No. just make sure its tight and dont forget keyway/cotterpin and it is seated good on the taper of shaft.
 
It's a key fit on a tapered shaft, and not a particularly high load, so enough torque to make sure it won't wiggle loose is fine. I'd say bottom out with your fingers, add a skoch with a wrench to be sure you are fully seated, then use the wrench to the next opening in the nut for the cotter pin. Remember that's a fine thread so don't get too enthusiastic.
 
My experiences with tapered joints in the aviation world is pretty general but this type of joint depends on not only solid fit and contact but the materials involved as well. The first rule of thumb is to avoid any form of lubricant on the tapers if there is no woodruff key involved. Anti seize is common on keyed shafts but it lowers the needed torque due to the lubricating qualities of the stuff. The caveat is a steel or stainless steel shaft with an aluminum casting being the rotor, too much torque can crack the casting. Ford never used an aluminum fan back in the day so any reference to OEM torque, if there ever was one specified, would likely be too much. Screw or bolt fasteners are either for tension or shear so they are in a completely different class than a tapered fit. Tapers can be seated with a torque of say 90 to 100 inch pounds but that torque can be loosened a bit and then retorqued to 65 to 75 inch/pounds. Now this is an educated guess but I sure wouldn't want to break a brand new aluminum casting. If the casting cracks, then the rotor can do serious damage when it lets go. The torque should be rechecked every so often to make sure the joint is secure.

If the manufacturer recommends a torque then definitely use that. A good daily inspection is to take hold of a fan blade then rock it on the shafts axis and see if there is any play. Any movement at all is to be corrected after visually inspecting the pulley area for cracks.

Some fans didn't fit the taper well due to shaft or fan hub manufacturing flaws and eventually caused movement on the shaft. In some cases the pulley started rubbing the pump housing. Keeping an eye on those fans is always a good idea.

This is Snyder's instruction link:
https://www.snydersantiqueauto.com/content/Snyders/Product_PDFs/A-8600-A ALUMINUM FAN.pdf
 
Careful about the interior conical slope of the two blade fans on the market at present. I added one two years ago and it kept getting loose. I finally really cranked down on it only to find that it still got loose. It eventually destroyed the pump shaft due to wobbling and being tightened to the point that it destroyed the shaft key. On close inspection I noted that the degree of change in the conical shaft diameter and that of the fan was different. I went with the 6 blade fan and found it to provide LOTS more airflow as well as being quieter...and it fit perfectly.
 
What is the preference of folks here, the two blade aluminum or six blade plastic? I have the radiator out so now is the time for me to make a decision. I did purchase the two blade aluminum but am willing to change it up of folks think the six blade works better.
Any input is appreciated!
 
I don't know, the two blade fan has seemed to work pretty good for almost 100 years. I remember hearing that the fan only cools when driving less than 20 mph. Just my opinion.
Marty
 
I run the aluminum 2 bladed fan I purchased it 10 years ago and the taper was correct from Snyder's I believe Snyder's is the 1 that manufactures them to begin with and sells them to other dealers!!!
 
Tighten the nut until the fan does not wobble and cotter pin hole aligns with the castle nut. A torque wrench is not necessary.
 
sconnors said:
What is the preference of folks here, the two blade aluminum or six blade plastic? I have the radiator out so now is the time for me to make a decision. I did purchase the two blade aluminum but am willing to change it up of folks think the six blade works better.
Any input is appreciated!
Click to expand...

You have the best fan, use it !

The more blades behind the radiator will stir more air , what cools your car is the air flowing into the radiator in front ! The two blade fan pulls more air into and through the radiator, one of the major clubs did testing, the two bladed fan had a higher mph air speed in front of the radiator !
 
The fan is basically there to draw air through while the car is not moving or operated at low foreward speeds. The real early cars had a fan shroud but the Ford engineers felt they were not all that necessary for average use so they were discontinued on cars. If I had a stationary engine then I'd want a shroud on there. Henry originally wanted thermo-syphon like the model T but Harold Hicks found pretty quickly that it wasn't going to work if they wanted 40-horse power out of that design. He even had Charles Sorensen's people change the casting of the block to get more coolant around the exhaust valves. This and the Zenith carburetor set up got them to 40-hp.

The OEM steel 2-blade fans worked fine until the steel started deteriorating due to corrosion and fatigue. The larger fans were for the AA trucks since they were mostly heavily loaded and rate of speed was a lot slower than any car.

More fan blades means less horse power. It doesn't affect it a lot but it does affect it.
 
You must log in or register to reply here.
Back
Top