thermal vs non-thermal fan clutch - The 1947 - Present Chevrolet & GMC Truck Message Board Network

redneckdds · 06-11-2006, 09:14 PM

whats the best option to go with?

**Boog** · 06-11-2006, 09:33 PM

GM factory fan clutches are of the thermal type. I believe they work better as after initial warmup it's only supposed to engage when the air temp coming through the radiator reaches a certain temp. Mostly freewheeling at highway speeds reducing the drag on your engine. Cost a bit more than some centrifugal clutches but I believe work better.

Longhorn Man · 06-11-2006, 09:54 PM

Thermal by far.

**clay68c10** · 06-11-2006, 10:49 PM

I found a big temp difference when I switched to a thermo clutch. Well worth the $$.

redneckdds · 06-13-2006, 12:15 AM

thanks guys... btw, I forgot to mention, the guys at autozone told me the Flex-fan is even better then using a thermal clutch??? I am just waiting for some stuff from the car and truck shop, then we can start up the crate for the 1st time. thanks again.

409biscayne · 06-13-2006, 01:57 AM

Stay with the factory thermal fan , flex fans can come apart . Not pretty.

**Stocker** · 06-13-2006, 08:42 AM

Quote:

Originally Posted by redneckdds

the guys at autozone told me the Flex-fan is even better then using a thermal clutch???

I once had a clutch fan go bad, and I installed a flex fan, correct size & all. That's the only time my truck overheated (in 30 years of daily driving). Clutch fan went back on (with new fluid in it), flex fan was traded for a half-rack of Bud.

Just say no to flex fans!

chevroletman19712001 · 06-13-2006, 10:44 AM

i have a flex fan in my 71 longhorn and it has never overheated and the fan is rated for 10,000 rpm. you dont have to worry about them wearing out. They look better as well. But...... they cost a little hp over a thermal fan. and you have to buy a spacer. so i would probably stick with thermal. unless you wanted to opt for a dual electric fan setup. as long as the motor is not too modded, they will keep it cool and free up hp.

Longhorn Man · 06-13-2006, 10:10 PM

Even the 10,000 RPM flex fans will wear out and fall apart, and when they do, it'll slice right through the hood and whom ever is in the way.
Besides, a flex fan won't do anything for cooling once you are over 2000 RPM.... like when you are hauling a seriouse load up a hill like pulling a boat out of the water on a slick ramp or hauling lots of wood and you're in the dirt... first gear and rev it up and hold it. That flex fan will do NOTHING and the temp WILL rise. A thermo fan turns the fan off when it isn't needed, and turns it back on when it is needed. No fan blades ripping through the hood, and no fragile electroncs to worry about like on an electric fan.
It is VERY hard to bear a good thermo clutch.

stope4 · 06-13-2006, 10:45 PM

I vote thermal, nuff said already.

06-11-2006, 09:14 PM	#1
redneckdds Senior Member Join Date: Nov 2005 Location: Queen Creek, AZ Posts: 218	thermal vs non-thermal fan clutch whats the best option to go with? __________________ '67/70 Chevy C/10 '10 2500 Crewcab Duramax 4wd

06-11-2006, 09:33 PM	#2
Boog laying low Join Date: Mar 2001 Location: Searcy, Ark. USA Posts: 13,452	Re: thermal vs non-thermal fan clutch GM factory fan clutches are of the thermal type. I believe they work better as after initial warmup it's only supposed to engage when the air temp coming through the radiator reaches a certain temp. Mostly freewheeling at highway speeds reducing the drag on your engine. Cost a bit more than some centrifugal clutches but I believe work better. __________________ Boog 69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver primer is finer 91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said. I stand for the flag and kneel at the cross

06-11-2006, 09:54 PM	#3
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: thermal vs non-thermal fan clutch Thermal by far.

06-11-2006, 10:49 PM	#4
clay68c10 Senior Member Join Date: Aug 2004 Location: Centennial, CO Posts: 2,979	Re: thermal vs non-thermal fan clutch I found a big temp difference when I switched to a thermo clutch. Well worth the $$. __________________ ClusterTruck: 68 C10 Bought in 89, wrecked in 03. Slow low $ rebuild started '17. 6.0 & TKO http://67-72chevytrucks.com/vboard/s...d.php?t=788602 93 K1500 Short Step, 350, NV4500, EBL flash ECU. Vortec heads & roller cam someday... 05 Jeep Wrangler Unlimited. 3” lift & 6-speed 02 E320 the insurance total “free car” 13 Tahoe LTZ

06-13-2006, 12:15 AM	#5
redneckdds Senior Member Join Date: Nov 2005 Location: Queen Creek, AZ Posts: 218	Re: thermal vs non-thermal fan clutch thanks guys... btw, I forgot to mention, the guys at autozone told me the Flex-fan is even better then using a thermal clutch??? I am just waiting for some stuff from the car and truck shop, then we can start up the crate for the 1st time. thanks again. __________________ '67/70 Chevy C/10 '10 2500 Crewcab Duramax 4wd

06-13-2006, 01:57 AM	#6
409biscayne Senior Member Join Date: Nov 2005 Location: Spokane , Wash. Posts: 790	Re: thermal vs non-thermal fan clutch Stay with the factory thermal fan , flex fans can come apart . Not pretty. __________________ Can-Am Motorsports 37 Chev Coupe 331 4 speed 5.13 posi . ex-gasser . 64 Biscayne 409 2x4 4 speed 4.11 posi 65 Nova Wagon Drag Car 383 t400 (Dragin-Wagon) 68 c10 cst 396 t400 a/c buckets lwb 4.11 posi (SOLD)

06-13-2006, 10:44 AM	#8
chevroletman19712001 Registered User Join Date: Jun 2006 Location: SC Posts: 47	Re: thermal vs non-thermal fan clutch i have a flex fan in my 71 longhorn and it has never overheated and the fan is rated for 10,000 rpm. you dont have to worry about them wearing out. They look better as well. But...... they cost a little hp over a thermal fan. and you have to buy a spacer. so i would probably stick with thermal. unless you wanted to opt for a dual electric fan setup. as long as the motor is not too modded, they will keep it cool and free up hp. __________________ 71 chevy longhorn 1 ton 79 chevy straight 6 79 burb 454 91 silverado 350 TBI and a few others that my brand loyalty wont permit me to post. Eureka Boys!!!!

06-13-2006, 10:10 PM	#9
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: thermal vs non-thermal fan clutch Even the 10,000 RPM flex fans will wear out and fall apart, and when they do, it'll slice right through the hood and whom ever is in the way. Besides, a flex fan won't do anything for cooling once you are over 2000 RPM.... like when you are hauling a seriouse load up a hill like pulling a boat out of the water on a slick ramp or hauling lots of wood and you're in the dirt... first gear and rev it up and hold it. That flex fan will do NOTHING and the temp WILL rise. A thermo fan turns the fan off when it isn't needed, and turns it back on when it is needed. No fan blades ripping through the hood, and no fragile electroncs to worry about like on an electric fan. It is VERY hard to bear a good thermo clutch.

06-13-2006, 10:45 PM	#10
stope4 Registered User Join Date: Jan 2006 Location: Houston Posts: 434	Re: thermal vs non-thermal fan clutch I vote thermal, nuff said already.

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