[RocktimusPryme]

After reading this I did a little indepentant research and have a question.

https://www.youtube.com/watch?v=QVMN7LmKLYA

This video shows a heavy duty clutch with an adjustment in it, which would be awesome, but Im guessing its only available in busses etc.

https://www.youtube.com/watch?v=UHWxqRWt9Kw

Another one with what looks like a later LS style truck fan.

Mick, you are saying moving the tip of the tank clockwise makes the fan engage at a lower temp. Both videos show moving the outter 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 arument. I have a severe duty clutch. Originally I used a 6 blade 18" Hayden aftermarket fan.

I got lucky one day at a swap and got a couple 19.5" 7 blade GM fans out of a $5 pile. So I switched to that. While my overall sustained temps are probably lower with the bigger 7 blade, I did notice that it got warmer faster with the bigger fan.

My theory is that with the 6 blade, the SD clutch was indeed never disengaging. It was always on, so it took my car longer to get to the thermostat. So I think there is something to the SD clutch maybe being the wrong choice unless you have a big honker of a fan.