Gary Lewis Posted May 5, 2023 Share Posted May 5, 2023 That's really good to hear, Chris! I too have a Four Seasons severe duty fan clutch. It seems to work well IME. Yes, that IS good news. Does it sound like a jet plane taking off? Link to comment Share on other sites More sharing options...
351FUN Posted July 14, 2023 Share Posted July 14, 2023 According to Hayden, this is the difference in clutch types • Standard Duty Thermal: Turns the fan 50-60% of shaft speed when engaged. Used with fans with lighter pitch (1-1/2" of pitch). Flat plate impeller design with 30 sq. in. of working surface. • Heavy-Duty Thermal: Turns the fan 80-90% of the shaft speed when engaged for increased cooling. Used with deeper pitch fans (2 1/2" of pitch). Land and groove design with 47 sq. in. of working area allows higher operating RPM's. • Severe Duty Thermal: Turns the fan 80-90% of the shaft speed when engaged. Used with deeper pitch fans. (2- 1/2" of pitch). Land and groove design with 65 sq. in. of working area. Larger working surface provides cooler running and longer life expectancy. Link to comment Share on other sites More sharing options...
Gary Lewis Posted July 14, 2023 Share Posted July 14, 2023 According to Hayden, this is the difference in clutch types • Standard Duty Thermal: Turns the fan 50-60% of shaft speed when engaged. Used with fans with lighter pitch (1-1/2" of pitch). Flat plate impeller design with 30 sq. in. of working surface. • Heavy-Duty Thermal: Turns the fan 80-90% of the shaft speed when engaged for increased cooling. Used with deeper pitch fans (2 1/2" of pitch). Land and groove design with 47 sq. in. of working area allows higher operating RPM's. • Severe Duty Thermal: Turns the fan 80-90% of the shaft speed when engaged. Used with deeper pitch fans. (2- 1/2" of pitch). Land and groove design with 65 sq. in. of working area. Larger working surface provides cooler running and longer life expectancy. Good info. Thanks! Link to comment Share on other sites More sharing options...
81-F150-Explorer Posted July 14, 2023 Share Posted July 14, 2023 According to Hayden, this is the difference in clutch types • Standard Duty Thermal: Turns the fan 50-60% of shaft speed when engaged. Used with fans with lighter pitch (1-1/2" of pitch). Flat plate impeller design with 30 sq. in. of working surface. • Heavy-Duty Thermal: Turns the fan 80-90% of the shaft speed when engaged for increased cooling. Used with deeper pitch fans (2 1/2" of pitch). Land and groove design with 47 sq. in. of working area allows higher operating RPM's. • Severe Duty Thermal: Turns the fan 80-90% of the shaft speed when engaged. Used with deeper pitch fans. (2- 1/2" of pitch). Land and groove design with 65 sq. in. of working area. Larger working surface provides cooler running and longer life expectancy. Our trucks also have a centrifugal fan clutch VS. thermal fan clutches. Centrifugal Fan Clutches do not have the coil spring on the front. Usually used with non-A/C systems. Centrifugal Fan Clutches never fully engage or disengage and are dependent with shaft speed on how fast they turn. Link to comment Share on other sites More sharing options...
ckuske Posted July 15, 2023 Author Share Posted July 15, 2023 Our trucks also have a centrifugal fan clutch VS. thermal fan clutches. Centrifugal Fan Clutches do not have the coil spring on the front. Usually used with non-A/C systems. Centrifugal Fan Clutches never fully engage or disengage and are dependent with shaft speed on how fast they turn. That is good to know! I had no idea when I bought it, I was learning about working on this truck in general. I just thought "Severe Duty" must be better, right?! That being said, my truck is staying nice and cool even with the warmer temps and my A/C running, so I'm a happy camper. Now that it is warmer out, the fan is engaged more often. And yes, it does sound like a jet or wind tunnel when engaged! It's still not louder than my C2 pump though. Link to comment Share on other sites More sharing options...
351FUN Posted July 15, 2023 Share Posted July 15, 2023 Our trucks also have a centrifugal fan clutch VS. thermal fan clutches. Centrifugal Fan Clutches do not have the coil spring on the front. Usually used with non-A/C systems. Centrifugal Fan Clutches never fully engage or disengage and are dependent with shaft speed on how fast they turn. Interesting, I'd never noticed they weren't thermal. Our clutch has the same fan mounting as GM, so I'll probably try the 11 blade fan soon to replace that flex fan garbage I have now. Link to comment Share on other sites More sharing options...
81-F150-Explorer Posted July 15, 2023 Share Posted July 15, 2023 Interesting, I'd never noticed they weren't thermal. Our clutch has the same fan mounting as GM, so I'll probably try the 11 blade fan soon to replace that flex fan garbage I have now. With the 300-6: with standard cooling, you got the small radiator, a fan guard, and a flex fan directly bolted up to the water pump using a fan spacer adapter. with super cooling without a/c, you got the larger radiator, a fan shroud, a solid fan, and a centrifugal fan clutch bolted up to the water pump with 4-Bolts (Trucks built before 1983). Some of the bolts are left handed threaded too. (Righty-loosey Lefty tighty) Best pictures I have of my setup. 300/6, Super Cooling, Without A/C. With super cooling with a/c you got a thermal fan clutch. The one with the temp spring on the front. I highly recommend swapping the supercooling components if your trucks only have the standard cooling system. They really were inadequate when new. In my opinion. I'm going to replace the centrifugal clutch on my 300/6 to the thermal clutch if my centrifugal clutch goes bad. Link to comment Share on other sites More sharing options...
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