FYI FORD MustangSteve's Ford Mustang Forum / Fan shroud on aluminum radiator with fan clutch for 65/66 Mustangs

**Posted by jkordzi** 2/25/2018 10:03 PM

If you're like me, you've occasionally cogitated the best cooling setup. I'm running a 2 row aluminum radiator, which has a core thickness of 2-3/4", which is about equal to a traditional 4 core copper radiator. For a while, I've wanted to run a clutch fan with one of the 3-1/2" improved fan shrouds. The 3-1/2" shrouds are a big improvement over the stock shrouds in that they cover more of the radiator and they are deeper, which translates to better suction from the fan. I like a thermostatic clutch fan (as opposed to a non-thermostatic clutch) because it only engages when it's needed, and freewheels at only about 20% or so engagement when it's not needed. Here's a primer from Hayden on fan clutches: http://www.haydenauto.com/featured%20products-fan%20clutches%20and%20fan%20blades/content.aspx

To my mind, if you're going with a mechanical fan, a thermostatic clutch fan is the best overall compromise in that it cools about as well as a non-clutch fan when it's needed, but saves power and gas when it's not needed. The problem has been that the stock replacement fan clutch (Hayden 2710, standard duty) was designed for the stock shroud. Therefore, on my 2-3/4" thick radiator, it's shaft is too long and places the fan too far into the 3-1/2" shroud for optimal cooling. Searching through the Hayden catalog, revealed the answer. Hayden also makes clutch no. 2711, which appears to me to be the only other clutch offered by them that will mount to the stock Ford water pump. This clutch is also a standard duty clutch, but has a shaft length that is shorter. See below for a comparison between (left to right) the stock 1965 A/C fan clutch (C4AA-C1), the Hayden 2710, and the Hayden 2711:

Curiously, although the Hayden 2710 in the middle is listed as a direct replacement for the 65 Mustang V8, it's shaft is a little shorter than the stock 65 fan clutch, but still too long for my application. Although the Hayden 2711 on the right is only about 3/8" shorter, that's enough to place the fan almost halfway in and halfway out of the 3-1/2" shroud with a 2-3/4" radiator, as is shown below:

One more thing - if you're in the market for one of those 3-1/2" fan shrouds, I recommend the one from Rhino Fabrications: https://rhinofabrication.com/product/1963-1966-falcon-ranchero-comet-fan-shroud/. It's ABS, is thicker than some of the others and is made by them in house. Because my aluminum radiator came with an engine side flange, I was able to mount the shroud on that flange and didn't need the Z brackets used to mount a shroud on a stock radiator.

**Posted by Daze** 2/25/2018 10:19 PM

Great info. Especially the picture of the 3 side by side. I wish I could have found something like that a couple of months ago. Did you have any problem with pore machining on the water pump mounting flange of that 2711?? I bought one from NAPA and it way out of spec and could not be bolted up. Then I bought one from O'Reilly's and it to was a little off (better than the Napa one) I still had to use my die grinder to get it to bolt up properly. They were both obviously made in the same factory and had the same part # printed on the front of the clutch.

**Posted by jkordzi** 2/25/2018 11:59 PM

Daze wrote:
Great info. Especially the picture of the 3 side by side. I wish I could have found something like that a couple of months ago. Did you have any problem with pore machining on the water pump mounting flange of that 2711?? I bought one from NAPA and it way out of spec and could not be bolted up. Then I bought one from O'Reilly's and it to was a little off (better than the Napa one) I still had to use my die grinder to get it to bolt up properly. They were both obviously made in the same factory and had the same part # printed on the front of the clutch.

Both fan clutches came from O'Reiley's and were made by Murray and (assume a Hayden re-brand) they carry the same 2710 and 2711 Hayden part numbers. I didn't have any problems with the machining of the shaft, and the fan spins true.

I should add that the shroud takes a 17" fan. The only standard rotation 17" clutch fans I could find were a Derale 17117 and a Flex-a-lite 6717. The Flex-a-lite fan has aluminum blades riveted to a steel hub. It's lighter but has a limit of 4,000 rpms. I noticed that a number of other aluminum bladed fans have this same rpm limit. The Derale is steel blades riveted to a steel hub and has a 8,000 rpm limit. The Flex-a-lite is noticeably lighter. Because the standard clutch only engages at 60-70%, it would probably not see the rpm limit bolted to my engine, but I went with the heavier Derale to be safe. CJ Pony and others sell the Flex-a-lite but don't note the rpm limit.

**Posted by Chaplin** 2/26/2018 5:58 AM

Good info, thanks. Which radiator are you using?

**Posted by jkordzi** 2/26/2018 9:45 AM

Chaplin wrote:
Good info, thanks. Which radiator are you using?

The radiator is an aluminum 2 row radiator that I bought off ebay. I like it because it has die-formed tanks so at first glance it looks similar to stock. I don't see the vendor there anymore, but there are some similar ones being offered. I imagine most are welded by teenage girls in China but mine looked pretty good and so far hasn't leaked.

**Posted by Daze** 2/26/2018 9:56 AM

Great minds think alike I just went through the same thing with my galaxie. These are the posts I made on my Galaxie forum

Found more parts (not for a 62 Galaxie) to put in my 62. Clutched fan

Daze wrote:
For those of you that have been here a while you know that I am all about customizing my car and using parts from any make, model, and year to maximize performance and function. To that end I have found another upgrade. My car is currently setup with an aluminum radiator, 302 and mechanical fan. I was able to use foxbody Mustang engine mounts to drop the 302 into my 62 without modification. The only issue is there is not a lot of space between the front of the engine and the radiator (about 3.5") In order to mount the fan I am currently running I used a short spacer and then a 17" flex fan. System works fantastic, moves a ton of air but it is also very loud and the constant spin of the fan eats HP. Being its a small block in a big car I need all the HP I can get.

A simple solution to this issue is a thermal clutched fan. The problem is most of them take up more space than I have. The key word there is most as I think I found one that will work. As You know most parts places want year make and model to find parts so it can be a challenge to find the correct part based on specs and not the car it was designed for but I have figured out some good ways around that. I went to Summit Racing and looked up fan clutches. A bunch came up, problem is their web site does not offer any measurements so I then took each part # from Summit and input it into Napaonline.com. The Napa web site is one of the best I have found to have measurement and other fitment specs. After checking a a dozen or more I found the shortest one they make that is still a 4 bolt for both the water pump and fan. Napa's site listed a fan mounting height of 1.4" but did not give me the entire height including the clutch piece so I went to Napa and measured one. Looks like 3" which should just barley fit. Original car this clutch was used on was an 1980 Cougar among other applications. I then found an aftermarket 17" fan that will bolt up to this clutch and ordered it. I will take some before and after pix and report back how it all worked once the parts come in and I get them installed.

Daze wrote:
Finally got the fan in the mail and picked up the clutch from Napa. Here is a pic of it all put together, next to the fan that I am replacing. I already did a test fit and the clutch will be about 3/8" from the radiator. a little closer than I would like but acceptable.

Daze wrote:
got it installed. Its a little bit quieter and should save on power. Have not had a chance to do much else with the car but I assume it will keep it nice and cool. seams to draw a lot of air even at "cold" speed.

**Posted by Bolted to Floor** 2/26/2018 11:53 AM

I was doing some digging for the same thing on my car and stumbled across another part number that is shorter than a Hayden 2711 on another site. I made a spread sheet to compare. Its Hayden 2765. Your Derale fan has a dual bolt pattern that will mate up to this clutch.

http://fepower.net/simplemachinesforum/index.php?topic=1179.msg10220#msg10220

Frankenford did reference a stud and nut for attaching since there was not enough room for a bolt.

I bought the Hayden 2711 for mine about 2 months ago from Rock Auto with the thought of using a fan I had already. Turns out the fan is too large a diameter for the factory shroud, so I will be buying an 18" version, Derale 17118, of the fan you listed from Summit. Wasn't till today I realized that both have the a dual bolt pattern for the clutch, or I would have went with the Hayden 2765.

Took a minute to figure out how to correct the chart to be readable.

Last edited by Bolted to Floor (2/26/2018 12:16 PM)

**Posted by jkordzi** 2/26/2018 12:12 PM

Bolted to Floor wrote:
I was doing some digging for the same thing on my car and stumbled across another part number that is shorter than a Hayden 2711 on another site. I made a spread sheet to compare. Its Hayden 2765. Your Derale fan has a dual bolt pattern that will mate up to this clutch.
Hayden 2765Hayden 2711Hayden 2710Bolt Quantity444Bolt Thread5/16-18 Hole5/16-18 Hole5/16-18 HoleClutch TypeB - Non-Thermal and Std ThermalB - Non-Thermal and Std ThermalB - Non-Thermal and Std ThermalColorRaw Aluminum in ColorRaw Aluminum in ColorRaw Aluminum in ColorDescriptionFan ClutchesFan ClutchesFan ClutchesDrawing TypeBBBDuty RatingStandardStandardStandardElectronic Clutch?Non ElectronicNon ElectronicNon ElectronicFan Bolt Circle IN3.2533Fan Mount Dia. IN2.622.372.37Fan Mount Height IN1.093751.41.75MaterialAluminumAluminumAluminumMeets / Exceeds OEM?YesYesYesMount Dia. IN2.322.332.33Mount Hole Qty444Mount TypeFlangeFlangeFlangeMounting Hardware?Not IncludedNot IncludedNot IncludedNew or RemanNewNewNewO.E. Replacement?YesYesYesOverall Dia. IN7.27.27.2Overall Height IN2.6718752.9843753.296875Performance Rated?YesYesYesPilot Depth IN0.560.750.75Pilot Dia. IN0.75.63 to .75.63 to .75RotationStdStdStdStyleSTANDARD DUTYSTANDARD DUTYSTANDARD DUTYTypeThermalThermalThermalWire GuageUses Original Equipment ConnectorUses Original Equipment ConnectorUses Original Equipment ConnectorWire QuantityUses Original Equipment ConnectorUses Original Equipment ConnectorUses Original Equipment ConnectorSource
http://fepower.net/simplemachinesforum/index.php?topic=1179.msg10220#msg10220

Frankenford did reference a stud and nut for attaching since there was not enough room for a bolt.

I bought the Hayden 2711 for mine about 2 months ago from Rock Auto with the thought of using a fan I had already. Turns out the fan is too large a diameter for the factory shroud, so I will be buying an 18" version, Derale 17118, of the fan you listed from Summit. Wasn't till today I realized that both have the a dual bolt pattern for the clutch, or I would have went with the Hayden 2765.

That Hayden 2765 looks similar but it has a 3.25 bolt circle for the flange that mounts to the water pump, whereas the ford water pump has a 3" bolt circle. Be careful about the fan - as far as I can tell the shrouds are made for a 17" fan and my shroud and 17" fan had about 1/2" clearance all around.

**Posted by Bolted to Floor** 2/26/2018 12:22 PM

jkordzi wrote:
That Hayden 2765 looks similar but it has a 3.25 bolt circle for the flange that mounts to the water pump, whereas the ford water pump has a 3" bolt circle. Be careful about the fan - as far as I can tell the shrouds are made for a 17" fan and my shroud and 17" fan had about 1/2" clearance all around.

The 3.25 pattern is for the fan to clutch pattern not the water pump.

I don't mean to confuse applications, but mine is on a 67 with a 390 and a 24"wide radiator and a factory shroud. The original fan diameter was 18.25 inches.

**Posted by jkordzi** 2/26/2018 12:53 PM

Yeah you're right - don't know what I was thinking.

**Posted by MS** 2/26/2018 9:56 PM

I noticed no air conditioner compressor was mentioned. If equipped with one, be sure the shorter clutch doesn’t put the fan blades into the compressor pulley. I think this is more of an issue if using a Sanden compressor with a double groove a/c clutch.

Glad you found the shorter fan clutch and the better quality shroud. Looks like a great solution.

**Posted by Richardsom** 8/21/2018 11:18 PM

Yep,the clutch has seen better days.
I need to buy a new one for my mustang.
It's a T5 transmission.
In it now is a ford motorsports clutch,and it done a good job this year.
What do ya'll suggest?
Pro's and con's please.

**Posted by MS** 8/29/2018 11:40 AM

That is a good looking shroud.

**Posted by Good Look'n** 3/31/2019 10:34 AM

jkordzi

Thanks for this very informative thread jkordzi....your info is exactly what I'm looking for....see>>
https://fyi.boardhost.com/viewtopic.php?id=9459

I'll be referring to this as progress moves forward.

**Posted by MS** 3/31/2019 3:10 PM

Careful on those derale fans with two bolt patterns. See Bullet Bob’s post on the custom hood scoop hole created by the derale fan that blew apart. If you look carefully at the extra bolt holes, they form a perfect place for the fans to start flexing until they ultimately come apart. It is apparently a defective design with known problems.

**Posted by Good Look'n** 3/31/2019 8:29 PM

MS wrote:
Careful on those derale fans with two bolt patterns. See Bullet Bob’s post on the custom hood scoop hole created by the derale fan that blew apart. If you look carefully at the extra bolt holes, they form a perfect place for the fans to start flexing until they ultimately come apart. It is apparently a defective design with known problems.

Thanks MS...I did speak (communicate, wrote??) w/ Bullet Bob on that. I sure as ..hel_...I mean heck, will stay away from that brand. Prefer a nice heavy steel thingie with lot's of blades...chrome would be neat as I did get that car for it's bling.

**Posted by MS** 4/02/2019 4:45 PM

You probably won't find a chrome fan. Hydrogen embrittlement ensues, giving you same likely results as installing a Derale brand fan. Polished stainless is fine, but usually only found in a flex type fan.

**Posted by jkordzi** 4/02/2019 9:50 PM

MS wrote:
Careful on those derale fans with two bolt patterns. See Bullet Bob’s post on the custom hood scoop hole created by the derale fan that blew apart. If you look carefully at the extra bolt holes, they form a perfect place for the fans to start flexing until they ultimately come apart. It is apparently a defective design with known problems.

As I indicated, the the only standard rotation 17" clutch fans I could find were a Derale 17117 and a Flex-a-lite 6717. The Flex-a-lite has a limit of 4,000 rpms like a lot of other aluminum bladed fans. The Derale is steel blades riveted to a steel hub and has a 8,000 rpm limit. Considering it's mounted to a clutch, I doubt it'll ever come close to that limit. I searched a number of reviews and forums and only saw the one youtube video claiming a failure. Other fans have come apart and a clutch fan is obviously is not a racing application .... but if there's a better clutch fan alternative I'd like to know about it.

Last edited by jkordzi (4/03/2019 3:56 PM)

**Posted by Good Look'n** 4/03/2019 10:41 AM

MS wrote:
You probably won't find a chrome fan. Hydrogen embrittlement ensues, giving you same likely results as installing a Derale brand fan. Polished stainless is fine, but usually only found in a flex type fan.

As I wrote that sentence, me thoughts went back to the late '60s, "Didn't I hear something about how you can't do that?" "I better research that when the time comes to get the fan"

Really...yup....I actually thought that...trust me on this...