Electronic fan clutch retrofit idea...

Looking into replacing the heavy duty thermal clutch on an RV 413 with one that can be switched.
The factory fan pulls up to 5,500 CFM through a 24" radiator, and I have not seen an electric combo that comes close.
That said, bigger trucks almost all run them: https://www.summitracing.com/parts/hda-3330
The trick is finding one that will bolt to the 4 screw pump with its 5/8" nose, or can be reasonably machined to fit.
Most also use the newer style fan that bolts to the perimeter of the clutch, which is fine.

Any truck radiator mechanics have ideas?

The problem with that is the fan itself. It's not meant to be direct drive which is what happens with an electric clutch...the fluid clutch never actually locks up. IOW, the belts might not have the ability to drive the fan direct.

The basic haydenauto.com type clutches spin 90% when hot, and this motor has ~4000rpm redline so not very fast, and dual belts.
I actually assume that the new RAMs etc with clutches have the matching large hub plastic fan like https://www.summitracing.com/parts/hda-8302
One concern is why these have 4-5 pins... if they expect CAN data it is a non-starter.

These for RAM 1500 https://www.ebay.com/itm/296187407367 might actually be an alternative if they can actually pull more air than the 1200cfm aftermarket models.

These https://www.dieselarmy.com/news/quick-hit-flex-a-lites-electric-fans-equip-diesels-for-long-hauls/ sell for ~$700

flex-a-lite type fans are an attractive option for their ability to run after shut-off and relieve hot-soak. But not $700 attractive.

All the newer Rams have electric fans attached to the radiator, they are not belt driven fans. Most truck (and car) cooling systems after about 2,000 have the electric fans on the radiator. The belts only drive the water pump. and other accessories.
Those electric fans replace your fan shroud and are independent of the water pump. You can buy them thermostat controlled, and powered through relays. Some of those move a lot of air. Those electric fans solve a lot of problems that belt driven fans can have and are very efficient.

Might be worth looking into.

I was looking at those like 2010-2018
I'd have to check if they fit, attachment points etc, but I'd assume they move air. Plenty of room with the OEM fan gone.
The 8HP70 controller is CAN and send the temp values, and has other AUX output, but I'd prefer a dumb thermal switch.

This actually looks viable https://www.summitracing.com/parts/flx-104811, size and 3,300 cfm
And this claims 4,600cfm https://www.summitracing.com/parts/flx-104242?seid=srese1&ppckw=pmax-vf-flex-a-lite

Still, it would be a LOT easier to just replace the clutch...

I bought a "kit" with an adjustable temperature setting so it will come on at what ever temp you want (within their pretty wide range), and will turn off when the temp drops so many degrees (10 I believe). They recommend you turn on the fans 10 degrees above the trucks thermostat rating. That kit came with either an insert into the radiator core sensor, or a screw into the cooling system temp sensor and relays (50 amp ratings) with wiring. It can run one or two fans, and will kick one fan on then the second shortly after. I bought the one I have off ebay for something around $50, then you buy which ever fan(s) you want.

Mine cycles on and off regularly once the motor reaches operating temp.

the only complaints I have with the controller I have is 1) The digital temp reads in degrees "C" rather the degrees "F". I had to do the conversion the day I set it. 2) It came without written instructions, you have to read the clearly printed wires to make the electrical connections. 3) The control is "water resistant", but not "water proof". It needs to be placed where it is protected from getting too wet. None of the complaints were much of an issue.

Stock clutch yes, Switchable one no. It can be done but will have to have parts made to adapt to motor/fan. To my knowledge no one makes a direct fit one. Another option may be go direct drive and replace the fan. Direct drive will have max air flow at low rpm and the fan blades will flatten out at high rpms. Or convert to electric is also a option.

my opinion on electric fans is, if you go that route, install factory fans.
they work way better than anything the aftermarket has come up with, are super reliable, and offer no [wildly] optimistic cfm ratings.
wire them correctly using relays and correct [heavy gauge] wire, and if you wish, an override switch. [i prefer this switch be to ground] you can also install a controller that ramps up the fan speed to only what is needed to cool, instead of a full on or off amp spike.
don't get me wrong, others have had success using aftermarket fans, but i'm not wildly impressed with their quality. in reality, what does one really expect from a $35.00 fan ? [which costs way more than it's worth]
more than likely you will have to modify the factory shrouding to get them to fit, or fabricate a shroud for your application, and install the factory fan to it.
just my old man opinion. your mileage will vary.

I tend to agree; the new RAM units should be fine. But, on this class A rig it is a lot of work to remove the radiator - necessary to remove the factor shroud. as well.
Tight quarters, not like my pickups or cars.

One of the reasons to switch would be to turn it off cruising the highway 65 on cooler days. A fan is really never needed unless climbing.

If I ever go to the trouble of pulling the rad I'd go serpentine as well.

a lot of work involved on just about any repair/replacement item on today's vehicles !

So, if the space to work is tight (I have no doubt), can you remove the current clutch fan without removing the current fan shroud?

I have not worked on your project, but I can tell you there are not many radiators with fan shrouds and clutch fan set ups where the clutch fan comes out without removing the shroud with it. It may look like it will come out, but usually something will prevent it from happening.

If you have to remove the shroud so you can get your clutch fan out to replace the clutch, I don't see how its that much easier to replace that mess then it would be to convert to an electric fan that is attached to a shroud the fits your current radiator. All you need then is to add the fan controller and wire it in, That only took me about a 1/2 hour to do.

The electric fan only comes on when the temp reaches the set point, and then it turns off when the temp cools down. Through most of the winter months, my electric fan doesn't run much. It will only come on if I'm sitting at a traffic light and often shuts off as soon as the truck starts moving. That electric fan speed is not connected to the truck motor's rpms at all, (you can buy fans and controllers that vary the electric fan speeds, but they are expensive, and honestly, I'd rather have the fan kick on at full speed and bring the temp down faster) and those electric fans don't pull HP from the motor to drive them. They come on, do their job, then turn off without driver input, but if you really feel a need to be involved, you can add a shut off switch to turn the fan off any time you choose, and turn it on as long as the temp controller says its suppose to be running. I'm betting that once you see how well that electric fan and controller works, your probably not going to want to be messing with any switch to turn it off. I do have my fan powered through the ignition switch so it doesn't run when the motor isn't running. That is the way the fan and controller companies recommend to power the fans.

You will notice the modern Ram radiators don't look like your radiator looks. The "factory" truck electric fans will require some effort to mount them to your current radiator. Buy a fan that fits your radiator. The current electric fans are much better then those produced in the early days, as long as you don't buy the cheapest crap fan you can find.

Yes, I replaced the stuck-on OEM a couple years ago, 8 7/16" screws



The 2018 V8 RAM rad is same height and 3 inches wider than mine prob because of the side tanks.
I would like the fan to stay on after shutdown as the 700lb 413 has a lot of heat after coming up the mountain and parking.
Because an E-fan will definitely require removing a lot of stuff, modding a couple of brackets is small change.
The A727-to-8HP70 swap has been a good number of new brackets and things...