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Discussion Starter · #1 ·
What is the difference between a thermal and non-thermal fan clutch. Which one do you recommend for my '57?
 

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A non-thermal fan clutch is just a viscous (fluid) coupling that lets the fan turn at close to engine rpm when you're idling or at relatively slow engine rpm. It slips when the engine rpm increases (which is also when you don't need the fan as much). It still slips a bit at all speeds.

A thermal fan clutch has a bimetal spring that activates a lockup when the temperature at the fan hub gets to a certain temperature (it's still not a solid mechanical connection). Otherwise it's similar in that it will freewheel at higher speeds.

If you're concerned about overheating at idle/low speed, the thermal clutch would be better.

When you look at the clutch units, the bimetal spring is right in the center of the hub on the thermal units.
 

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Discussion Starter · #3 ·
A non-thermal fan clutch is just a viscous (fluid) coupling that lets the fan turn at close to engine rpm when you're idling or at relatively slow engine rpm. It slips when the engine rpm increases (which is also when you don't need the fan as much). It still slips a bit at all speeds.

A thermal fan clutch has a bimetal spring that activates a lockup when the temperature at the fan hub gets to a certain temperature (it's still not a solid mechanical connection). Otherwise it's similar in that it will freewheel at higher speeds.

If you're concerned about overheating at idle/low speed, the thermal clutch would be better.

When you look at the clutch units, the bimetal spring is right in the center of the hub on the thermal units.
Thanks Rick. Thats what I needed to know. :tu Now I will definitely be going with the thermal fan clutch.
 

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Hi Rudy. We last visited at October NSRA Cal Expo event. I hope all is going well with you. Did you end up going to Pleasanton last weekend? I did not make it.

Good question...I want to swap out my noisey electric fan with a mechanical clutch fan. So I was highly interested in the thermo clutch answer you received above. Please let us know what you end up selecting for your fan blade and thermo clutch and shroud. My radiator is in 6 cyl position with hopefully enough room for a thermo clutch/fan/shroud between radiator and Ramjet 350V8 in place of present puller electric fan/shroud combo. How much room is required between water pump pulley and radiator to accomodate a thermo clutch fan? How much room do you have on your 57?

Anybody else have suggestions/recommendations for us?

Thanks,
Jim
 
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