With all of the threads on HD cooling, I figured I would discuss fan clutches. When I was first looking into adding the HD cooling I remember reading some threads on what clutch to go with but I wasnt able to find them today. Seems I remember people trying to figure out which clutch was best. Dont ask why, but many years ago when I added the HD cooling, I couldnt remember what clutch I bought. I always thought I bought the Hayden clutch meant for the KJ and it was just a heavy duty fan clutch... Nope... I evidently bought the severe duty fan clutch that isnt meant for the KJ at all, it fits the 5.2 ZJ. Its SUPER tight getting that thing in and out of there. Unfortunately when I removed it today, I shaved the insulation off the wiring for the electric fan... Doesnt appear to have hurt the wiring itself, so I'll patch that up and move on. I was looking at the shaft and I noticed its much longer than the picture I found online. Thats when the little wheel in my head started turning and I found the number on my fan clutch... So FYI, the Hayden 2791 is the severe duty clutch with a longer shaft that screws onto the water pump. Im thinking this is why its so tight when trying to fight the electric fan, mechanical fan, and shroud. This clutch pretty much roars all of the time and Im thinking this may be why my fuel mileage always seems 2-3mpg low. Even on the 90F+ days and towing, that engine stayed at 200-204F. Electric fan only kicked on when the transmission got hot or the A/C was on. I was bored today so I tried messing around with the bimetal spring on the clutch. I took it out of its little home and fully loosened it. Started the Jeep and let it run for ~10min, the fan was still roaring... So trying to manually adjust it was out of the question. The Hayden 2736 is the factory replacement and I have one on order. Going to follow up on when it seems to engage and what temp the engine runs at. Probably have to wait till summer to really check it out. I'll get a pic of the two clutches side by side showing the differences when the 2736 clutch arrives.