School me on Black Aisin Fan Clutches

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kidglove13

kidglove13

Joined
Feb 25, 2009
Threads
176
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3,575
Location
Richmond, VA
Ok, So I replaced my failing black fan clutch with another black one that I cleaned up and put 15k oil in.
Truck runs fine, temps around town are consistently 190-195
On the trails crawling the thing roars like crazy and temps stay nice.

How do these hubs actually work?

At what temps should the clutch start working and shut down?

I know that they are adjustable.

How does adjusting them affect the performance of the clutch?

How does adjusting them affect the temps?

Thanks
 
Glad someone asked this question before me ;-)

I had a 94 that roared on startup. I've never heard my 97 roar in the 6 years I've had it, and temps (via Ultragauge) are just fine. Original black hub fan, Toyota belts, rad, etc.

I've heard/read that some of the fans in the later 80's may be a little more "subtle" like mine appears to be? Having read how to mod them, I still want to get a better picture of how they actually work from the fan senseis here.
 
The black hub on my '93 roars louder than any fan I've ever heard (well, maybe not the 100% drive fans that are used on newer big rigs).

However, mine is modded with 15k fluid, and is timed to 95°. Just modding it with 15k fluid made a pretty big difference, and I ran that for about 6 months. During the record that we had this summer, it still wasn't cutting it though. While pulling my trailer in the 110+ temps, it would still kick the A/C off.

That's when I decided to time it. The factory setting was 118° before it would start to open up, so that explained why it was still getting hot.
I adjusted it down to 95°, and it made all the difference. It now ROARS when it's hot out, and I can feel the increased drag on the motor, but it's worth it.

Went on a wheeling trip (after I timed the fan clutch) with about 10 other rigs, and I was the only one pulling a trailer. Temps were 105-110°, and we were all in low range 1st/2nd climbing out of a steep valley. The group had to stop several times on that climb out, due to rigs overheating. Mine was the only one that didn't get hot, and my A/C was blasting ice cold the whole time.

A modded/timed black hub combined with a high-idle switch is, IMO, the winning ticket for an 80 series.
 
How did you time it to cut on at 95*?
 
I have my other black clutch which I am going to pull apart and look at.

The one thing I have noticed after I swapped in the other black clutch is that my temps are about 5 degrees hotter than with the old one with worn out fluid.

Do you think that there could be a difference between the 2 clutches at what temp they start to open?

Could that explain the difference in temps from one to the other?

I am not concerned about my temps they are acceptable and have never been an issue thus far.

I am just curious.
 
The 96-97 usually use the Eatons so they are quieter and don't have the roar. I just did a new style fan clutch last night with 30,000 CST and temp modded to 95*

We shall see if it works. Several weeks ago I was reading 208* on the freeway going 70mph in 100* weather with A/C running.
My junk is pretty heavy and I have 315's and 4:88's.

My cooling system is all new with koyo rad, new aisin pump, thermostat and a blue hub clutch with 20k fluid. No temp mod on this current clutch.

The amazing thing was turning on both heaters dropped the temps down to 195*. I know this temp is still in the acceptable range. However my buddy traveling with us in his 80 (heavier in weight, 315's, stock gears)was only hitting 195 on the same drive. I modded his clutch also with 20k.

Hopefully it's not a HG. No bubbles though.
 
kidglove13 said:
I have my other black clutch which I am going to pull apart and look at.

The one thing I have noticed after I swapped in the other black clutch is that my temps are about 5 degrees hotter than with the old one with worn out fluid.

Do you think that there could be a difference between the 2 clutches at what temp they start to open?

Could that explain the difference in temps from one to the other?

I am not concerned about my temps they are acceptable and have never been an issue thus far.

I am just curious.
Click to expand...


I think there can be a variance between the clutches. I think there is 2 things that can affect it.

1. Variance from the factory when manufactured
2. Possibly the spring loses tension over time.
 
duggy said:
How did you time it to cut on at 95*?
Click to expand...


There are a few write-ups on here about that. Basically, you separate the clutch, set the half that contains the bi-metal spring in a pan of water. Place a digital thermometer in the water, and gradually begin to warm it up on your stove-top. Watch closely for when the valve begins to open up on the clutch, and make note of the water temp at that time.

To adjust, loosen the two philips screws inside the clutch (the only 2 screws in there), and warm your water to 95°. At that point, you can "time" the clutch by twisting the valve plate so that it's just beginning to open. Tighten down the 2 screws, and re-assemble.



yellowgeko said:
what do you mean with a high-idle switch? i have not heard of this before. is this switch for the idle of the fan clutch?
Click to expand...


I have a high-idle control box in my rig, and it's honestly the most used accessory on my truck. I practically use it everyday, especially when it's hot outside and I have to run inside a gas station/convenience store.

All it does is just bump up the engines idle to a preset RPM whenver I flip the switch. I usually just leave it set on 1500rpm, but I can change it on the fly to any RPM range.
The high idle allows for the engine fan to move tons of air when the vehicle is sitting. That keeps the A/C ice cold...

I also use it when I'm winching, as it spins the alternator faster to keep up with the increased load.

Details on my setup can be found here:

https://forum.ih8mud.com/80-series-tech/539339-controlling-cruise-control-module-2.html


Similar results can be had with an OEM Hand Throttle, but from what I hear, the hand throttles don't like to be used that often. I use this (electronic) setup several times a day, and it's been flawless.
 
Tim,

Very useful information. Thanks and I will be looking into this when I replace my fluid this weekend.
 
Are you guys changing fluids on used clutches or new ones?

Sent from my hawn finga using IH8MUD
 
busmup808 said:
Are you guys changing fluids on used clutches or new ones?

Sent from my hawn finga using IH8MUD
Click to expand...


We are changing fluid in both old and new clutches. Most guys are changing fluid in the new OEM Aisin blue hub clutches due to how "weak" they are compared to the older clutches. They come stock with really thin fluid.

I don't know much about the 3FE clutches though.

Will a 1FZ clutch fit/work on the 3FE engine?
 
Rwhat said:
We are changing fluid in both old and new clutches. Most guys are changing fluid in the new OEM Aisin blue hub clutches due to how "weak" they are compared to the older clutches. They come stock with really thin fluid.

I don't know much about the 3FE clutches though.

Will a 1FZ clutch fit/work on the 3FE engine?
Click to expand...

Mahalos

Sent from my hawn finga using IH8MUD
 
Rwhat said:
We are changing fluid in both old and new clutches. Most guys are changing fluid in the new OEM Aisin blue hub clutches due to how "weak" they are compared to the older clutches. They come stock with really thin fluid.

I don't know much about the 3FE clutches though.

Will a 1FZ clutch fit/work on the 3FE engine?
Click to expand...

You don't want a blue hub 1FZ fan clutch on a 3FE. In fact, you want to go the other way.

Kevin did an excellent write up on fan clutches in the below thread. It should be required reading:

https://forum.ih8mud.com/80-series-tech/601888-worth-doing-blue-hub-fan-clutch-mod.html
 
Rwhat said:
I understand that you would not want a blue hub in the 3FE, but will it fit? are the clutches interchangeable...
Click to expand...
Pretty sure that the 3FE clutch is a lot shorter than one from a 1FZ. There is also a difference in the fans, as they sit at different depths on the clutch body. Both of these can cause the fan to be too close to the radiator core.
 
inkpot said:
Pretty sure that the 3FE clutch is a lot shorter than one from a 1FZ. There is also a difference in the fans, as they sit at different depths on the clutch body. Both of these can cause the fan to be too close to the radiator core.
Click to expand...


Good to know. That's exactly what I wanted to know.
 
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