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View Full Version : thermal/ non-thermal fan clutch? JG_80Z 06-07-2005, 01:36:00 AM What's the difference between these two? I'm looking at buying a replacement. ------------------ Jeff 1970 Bigblock Z28 (http://members.shaw.ca/JeffZ28/jpgs/jeffzed2.jpg) Better than Sex (http://members.shaw.ca/irocz/images/stash.jpg) 73454 06-07-2005, 01:42:00 AM The non-thermal clutch freewheels at higher RPM, and the thermal clutch grabs only when there's hot air present through the radiator, sufficient to heat the viscous fluid to a point where it makes the fan spin at or near the water pump speed. JG_80Z 06-07-2005, 10:07:00 AM So which is better? ------------------ Jeff 1970 Bigblock Z28 (http://members.shaw.ca/JeffZ28/jpgs/jeffzed2.jpg) Better than Sex (http://members.shaw.ca/irocz/images/stash.jpg) CoryM 06-07-2005, 12:24:00 PM Clutch fans are better. Fans cost horsepower/fuel to spin them. Clutch fans only come on when your engine is hot so you dont lose HP and mpg when you dont need a fan. Also its easier on the waterpump bearings. ------------------ Currently Camaroless JG_80Z 06-07-2005, 12:29:00 PM <font face="Arial,Verdana" size="2">Originally posted by CoryM: Clutch fans are better. Fans cost horsepower/fuel to spin them. Clutch fans only come on when your engine is hot so you dont lose HP and mpg when you dont need a fan. Also its easier on the waterpump bearings. </font> You're talking about the thermal clutch fan then? ------------------ Jeff 1970 Bigblock Z28 (http://members.shaw.ca/JeffZ28/jpgs/jeffzed2.jpg) Better than Sex (http://members.shaw.ca/irocz/images/stash.jpg) CoryM 06-07-2005, 06:38:00 PM Yep. They are called thermal clutch fans because they use heat (thermal energy) to control them. ------------------ Currently Camaroless Todd80Z28 06-07-2005, 09:30:00 PM Note that the thermal clutch design (which is what GM spec'd on the car originally) will also freewheel/slip at high RPM. MacDaddy 06-08-2005, 07:48:00 PM <font face="Arial,Verdana" size="2">Originally posted by Todd80Z28: Note that the thermal clutch design (which is what GM spec'd on the car originally) will also freewheel/slip at high RPM.</font> By high RPM, what do you mean? In the 5000+ RPM range? My Suburban's thermal fan clutch will engage at 3500 RPM on a hot day. You can sure hear that thing moving the air. Sounds almost like a B-17 bomber. http://www.nastyz28.com/ubb/wink.gif ------------------ Gordon 1979 Camaro Berlinetta |
