Fan Clutch Selection

Topic: Fan Clutch Selection (Read 9294 times) previous topic - next topic

Fan Clutch Selection

Reply #15 – August 05, 2014, 08:52:03 PM

I agree those 75 AMP Bosch relays are tried and true.

Fan Clutch Selection

Reply #16 – August 07, 2014, 04:55:45 AM

Pic before tpuppies the tabs off the sides and fitting to the rad.

Fan Clutch Selection

Reply #17 – August 07, 2014, 10:59:50 AM

Please pay attention to the wiring diagram Foe posted as the resistor is very important. For a Lincoln Mark VIII fan you will need to run a diode or the high inrush when it first starts will kill the fan motor in about a year or so. That nugget of info is from personal experience of wiring it without the diode.

I wired something similar back in the day and for the cost savings versus a DCC Controller I would not mess with it ever again. The DCC Controller has been flawless and can compensate for underdrive pulleys, comes with a temperature probe that is installed in-between the fins on the radiator near the outlet to the motor, an input for A/C if the car is equiped, and a cool down function can be wired (one wire from the ignition) which keeps the fan running for a couple of minutes after the car is shut off. Some people will say that they have had issues with either customer service or the unit itself but I have bought three units for myself and one for a buddy's wife to give him for a present and all have been easy transactions and worked great.

To each is their own and I do understand the satisfaction of doing it yourself and saving money in the process.

This website has basically been the one everyone else has ripped of over the years and reposted on other sites. Basically the bible for Fox Mustang owners with regards to the 3G upgrade as well as electric fans. He has some other good stuff on there too:

http://www.geocities.ws/smithmonte/Auto/MarkVIII_Fan.htm

Darren

Fan Clutch Selection

Reply #18 – August 07, 2014, 11:39:38 AM

I don't know what my resistor is going to have to do with inrush, I use it to limit current for low speed only. If the air isn't on when the high speed kicks up, the resistor isn't even a part of the conversation. I also don't know what a diode is going to do about inrush, only a soft-start or a large capacitor would be of any use.
My first electric fan had a dryer capacitor wired to it to soft-start the fan, because it was 1-speed and the motor was already bad when I salvaged the fan. The fan would draw so hard on it's startup that sometimes the engine would stall. I canned that POS, and built my own 2-speed setup, and it's been trouble-free for over a year.

Fan Clutch Selection

Reply #19 – August 07, 2014, 06:41:01 PM

I think the mark8 fan is way overkill for most of us. it pulls over 60amps under continuous duty. the bigblock offroad chevy guys run the taraus fan with no issue. i also like the two speeds and dual temps of the volvo controller because it will turn the fan on with less then 30 amps start and pull lesss then 30amps when the high speed kicks on.

Fan Clutch Selection

Reply #20 – August 08, 2014, 12:04:12 PM

Just want to clear up amperage draw with the Mark VIII and Taurus fans with regards to start up amperage and running amperage. Lots of folks have heard of the huge start up and running amperage draws of these fans with the Mark VIII being the monster. It is all just simply not true. Here is a YouTube video of a gentleman showing the amperages on a Taurus fan:

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

Here is a writeup on these two fans:

http://www.thehollisterroadcompany.com/TaurusMarkVIIIrelay.html

Just wanted to clear that up and shed some light on this as they are not the power hungry monsters everyone swears up and down that they are. The biggest problem with most electric fan installations on cars that never had them is the lack of electrical knowledge and not using the right wire, relays, etc.

Darren

Fan Clutch Selection

Reply #21 – August 08, 2014, 12:10:12 PM

Foe,

With regards to my comment on the diode, I should have elaborated much more on this and thank you for calling me out on it as it was in no way complete. I was not writing down all the things I was thinking when I saw the resistor. It basically reminded me to say something about the freewheeling diode that one should install if you are using relays to run the fan. I pulled this right off of Monte's website which explains it better than I can:

FREEWHEELING DIODE
Since the motor is an inductive load and an inductor is an energy storage device, when the contacts of the relay open, the energy that is stored in the motor has no place to go. The voltage increases (negatively) and a spark is created across the relay contacts, greatly reducing the contact service life. If a diode is placed (reverse biased) across the motor, it will not conduct in normal operation but will conduct when the relay contacts are opened, thereby supressing the spark. The current is said to "freewheel" through the diode and the motor after the supply current from the battery is interrupted. This voltage spike can get unbelievably high, hundreds of volts for a 12V system. Use a 1N5404 which is rated at 3A, 400PIV.

Darren

Fan Clutch Selection

Reply #22 – August 08, 2014, 03:42:28 PM

Quote from: thunderjet302;436807

I may upgrade one day but I would have to upgrade the electrical system first. For now the fan and clutch work fine.

I shoulda stopped bitching and bought another one before the guy actually ran out of them. I want one for the black cougar too....though I may swap it from the red car, that one just doesn't come out much anymore. The black one needs to be able to do good burnouts and it has 100 more ponies. It does good but the fan doesn't come on much below 180. I run a 160 stat in both cars. Clutch is obviously intended for 180 / 195 degree stats. However, with the PI clutch in the red car, three bars all the time, and when it's hot outside, I HEAR that thing. Then it cools down and goes silent once more.

One time I tested the red cougar without any fan on and compared to having the PI clutch on in cool conditions. Seemed the same to me. I believe the claim: it cools better when needed, and when not needed, doesn't drag the engine down much. Hopefully someone will uncover another load of 'em somewhere, sometime...

Fan Clutch Selection

Reply #23 – August 08, 2014, 04:54:22 PM

Quote from: Aerocoupe;436924

Foe,

With regards to my comment on the diode, I should have elaborated much more on this and thank you for calling me out on it as it was in no way complete. I was not writing down all the things I was thinking when I saw the resistor. It basically reminded me to say something about the freewheeling diode that one should install if you are using relays to run the fan. I pulled this right off of Monte's website which explains it better than I can:

FREEWHEELING DIODE
Since the motor is an inductive load and an inductor is an energy storage device, when the contacts of the relay open, the energy that is stored in the motor has no place to go. The voltage increases (negatively) and a spark is created across the relay contacts, greatly reducing the contact service life. If a diode is placed (reverse biased) across the motor, it will not conduct in normal operation but will conduct when the relay contacts are opened, thereby supressing the spark. The current is said to "freewheel" through the diode and the motor after the supply current from the battery is interrupted. This voltage spike can get unbelievably high, hundreds of volts for a 12V system. Use a 1N5404 which is rated at 3A, 400PIV.

Darren

My first setup would ground both sides of the fan motor when everything was off, but the limitations of the setup would have made it very complex to do that AND have soft-start AND a low speed like I have now. If I damage the relays with the kickback I'll just replace them. I have a nearly endless supply as a side benefit of my job.

Fan Clutch Selection

Reply #24 – August 08, 2014, 06:17:27 PM

Quote from: Aerocoupe;436924

This voltage spike can get unbelievably high, hundreds of volts for a 12V system. Use a 1N5404 which is rated at 3A, 400PIV.

Darren

Any know a source, or where to buy something like this??

Fan Clutch Selection

Reply #25 – August 09, 2014, 12:25:52 PM

So a little information for yall: A mustang fan is much smaller in diameter than whatever came on our cars as can be seen in the photo below.

So yup. At this point in time I guess I'm either waiting to grab my other fan shroud sitting at my buddies out of town or grabbing a 20 inch fan off of another vehicle.

Also, I know this is a small community, but I feel like this forum would benefit from either some moderation or some guidelines. If someone wanted to search for information about fan clutches they'd have to sift through 2 pages of irrelevant content just to follow the actual thread. Maybe it's just irksome to me, sigh...

Fan Clutch Selection

Reply #26 – August 09, 2014, 02:10:24 PM

That wavy "flower" shape in the middle of that fan hub doesn't look right.

I bought a 9-blade Mustang fan for my black cougar, I also thought initially it was small...but I'm pretty sure it fits inside the shroud the same way the one I had did.
I'm out of town now but I'll look at it when I get home. I swear I thought it was small when it came in the mail but then I stacked it on top of my stock 7-blade and it was the same circle...

Fan Clutch Selection

Reply #27 – August 09, 2014, 04:10:59 PM

Quote from: mcb82gt;436935

Any know a source, or where to buy something like this??

Radioshack is you want to pick it up in person.
http://www.radioshack.com/product/index.jsp?productId=2062579
Digikey, and Mouser are what I use for most stuff that I don't need right now.

http://www.digikey.com/product-search/en?vendor=0&keywords=1N5404
http://www.mouser.com/Search/Refine.aspx?Keyword=1N5404

Digikey and Mouser carry so many parts, sometimes it is hard to decide on what to buy. Want a 450 ohm 1/4 watt thru-hole resistor? Digikey has 25 options!

Fan Clutch Selection

Reply #28 – August 09, 2014, 07:34:18 PM

I've been working on my 71 Comet and experimenting with different cooling methods as I no longer race and want it for street only. I looked through my stash and found a couple of items one of which was a 88 LX HO fan. I couldn't use it due to REV rotation. I measured it and it is 18", 9 blade which looks nothing like what grannysbird posted.
On a side note, I went with a Taurus wagon fan and modified the shroud. Using a down flow rad leaves few options.
One other thing, a 35amp alt won't cut it......ask me how I know.

Fan Clutch Selection

Reply #29 – August 09, 2014, 08:27:53 PM

WOW what do you know the guy uses a Bosch 75 AMP relay. Where have we heard that before?? Anyway a clamping diode is very useful no question about it. But not needed. I have been running those relays for many many years with no issues whatsoever. Never burned out a fan motor either. And never seen a car company use a clamping diode either. But it is possible some manufacturers do. The reverse EMF is a real thing but not an issue as i said could be wrong. . Never had a relay go south. But the instillation on that mustang is as crude as it comes. never mount a relay or anything close to the battery when it can corrode the electronics. I personally never use a sensor that is not physically in the coolant. And the car companies also do not do it. That is risky and can cause a false reading. Basically what is going on here is complicating a simple fan circuit and beating it to death. FAN RELAY AND SENSOR IN THE COOLANT STREAM. Done Finished and over. just me and my opinion. Have a great day guys.