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Old 07-09-2020, 03:10 PM
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lust4speed lust4speed is offline
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Join Date: Jul 2002
Location: Yucaipa, SoCal
Posts: 8,836
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Quote:
Originally Posted by RocktimusPryme View Post
...Mick, you are saying moving the tip of the tank clockwise makes the fan engage at a lower temp. Both videos show moving the outer tang counter clockwise to lower the engagement temp of the fan.

Am I misunderstanding what you are saying?

A little wisdom of my own on the subject. Many have said that the SD Harden clutch is a bad option. That it will just never disengage on normal car duties. Its a big ongoing agument...
Confusion might come in because I was trying to describe the actual bending of the tang. To simplify things the center pin has to move counter-clockwise to have the clutch engage earlier. So if bending the tang sticking out of the coil it is bent a little clockwise which forces the coil and center pin counter-clockwise. Somewhat confusing.

We have about 10 members in our GTO club that I have talked into the severe duty fan, and one of those complained and removed it. I have the SD clutch on 4 Pontiacs and they cycle properly with the stock fans. My blue GTO has the SD fan on it with the original H.O. 18" fan and it cycles fine. That club member donated the removed clutch fan to me but it's sitting on the shelf and I haven't tested it to see if it might be defective. It is as sold and he didn't play with the spring so I'm really thinking that it might be locked up out of the box.

Hayden changed the specs of the heavy duty fan clutch and brought the specs up so close to the SD clutch that it should work very similar now. Old HD clutches were way low on their lock up percentage but new ones are pretty high.

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Mick Batson
1967 original owner Tyro Blue/black top 4-speed HO GTO with all the original parts stored safely away -- 1965 Catalina Safari Wagon.