Custom fan clutch eliminator? Recording of noise available?

[rickoregon]

I was following a thread from last Summer entitled "clutch who makes a good one" that Bucket had posted. It's at:

http://www.naxja.org/forum/showthread.php?t=63826

Lots of good suggestions, one of which was to eliminate the fan clutch entirely using a bolt through the existing clutch and welding the bolt.

Another approach suggested was using a universal spacer or one that is custom made.

5-90 was thinking of making one just for XJ 4.0 engines .. see http://www.geocities.com/JeepI6Power/coming.html). Jon, did you ever make any of those aluminum spacers?

I'm thinking of making a spacer out of a pully or using the bolt-through-the-center approach.

It would be interesting to hear just how loud the fan is before and after using a clutch eliminator, though.

Does anyone with a fixed fan have the means to record what your fan sounds like at idle and at 1500 and 3000 rpm? If so, please email the recording (mpeg?) to me or upload it to this thread.

Any insights on recent accomplishments fan clutch eliminators would be appreciated. -Rick

 

[Crawler]

I tried putting screws through an old fan clutch once. It seemed to have worked pretty well. I don't have a recording, but trust me... it was loud!

 

[Blaine B.]

The fan isn't supposed to spin over a certain RPM, or it can literally break apart.....and, besides, your fuel mileage and power will lack with the fan "locked" all the time.

 

[5-90]

Not yet - I've spent the last year recovering from an incident last November, and it's pretty much taken all of my energies and time. I'm getting back on track now...

I also have to either find or re-create entirely the production drawings I did of the part, and select material. I'm not sanguine about going with aluminum on this, but I haven't found a coating I like for using steel just yet (and using steel "in the white" is something I really don't feel good about!)

I'm aware of the "speed limit" on fans, but I'm willing to bet that most of us don't run past about 3500rpm anyhow. And, I've been thinking recently of running an "underdrive" pully turned in conjunction with the part - I just haven't decided how much to underdrive the fan (which should help make up for the 100% mechanical coupling that you'll get.) So, more research there is certainly indicated.

Upshot? I'll probably be keeping this thing "under development" for a little while, and running an extended prototype cycle for the part (something like six months' daily use, I think.)

I do also plan on recording the "before and after" noise of the fan, just for comparison purposes. The mpegs would be made available through my site in order to help make a more informed decision - it's just a part of what I do (and I'm just about always willing to answer questions to help you move forward anyhow.)

I'll probably keep digging on this anyhow - since I'm doing parts research for my second book. And if you don't think that is something that takes a lot of time, I've got a bridge to sell you...

5-90

 

[rickoregon]

I understand your wanting to get the part done right, 5-90. That's good.

Does anyone know the rpm limit on the fan? Is it over 5000?

Would it be possible to pursue this a different way -- how about replacing the fluid in the fan clutch (there is a fluid in there, right?) with a fluid that is much more viscous? Would that be possible? -Rick

 

[5-90]

There is a fluid in there - I think it's a silicone-based fluid with odd viscosity/temperature properties (synthetic - that I'm sure of!) It actually gets thicker with elevated temperatures, which is the reverse of normal behaviour.

Mainly, what I need to do (to decide the underdrive to apply,) is to measure the two pullys to get a drive % figure (I've got both - just haven't measured them yet,) and then find out what the "slip %" of the fan clutch is. Then, I can figure out how much underdrive to build into the pully, and the figure out what length of belt would then be required (a lot of work for a short trip, no?)

And, I do want to proto this on one of my own rigs first - a guiding rule of WiP designs is "If I won't run it on my rig, it's not going on yours." It's really that simple.

5-90

 

[rickoregon]

There is a fluid in there - I think it's a silicone-based fluid with odd viscosity/temperature properties (synthetic - that I'm sure of!) It actually gets thicker with elevated temperatures, which is the reverse of normal behaviour. ...

Interesting, isn't that what happens with a multi-grade gear oil, like say 85w140? When it's colder, the oil acts like an 85 weight? When it's hotter, it behaves like a 140 weight? Perhaps I could drill and tap holes into the fluid area, one from each side for balance. Then drain the existing fluid and try some other types... using plugs of equal size to keep fluid in and maintain balance. Do you know where I could find a technical diagram that shows the make-up of the fan clutch?

 

[Vanquish]

I welded my fan solid and it held for as long as I had the truck, and I beat the hell out of that thing. The power loss was definitely noticable, but the fan itself wasnt all that loud.

 

[Vanquish]

Also it's just not worth all this extra effort, just buy a 10" electric fan which cools better, and you'll get all your power back, with no noise or loss of fuel economy. I had 2 10" fans of my rad, worked beautifuly

 

[5-90]

Interesting, isn't that what happens with a multi-grade gear oil, like say 85w140? When it's colder, the oil acts like an 85 weight? When it's hotter, it behaves like a 140 weight? Perhaps I could drill and tap holes into the fluid area, one from each side for balance. Then drain the existing fluid and try some other types... using plugs of equal size to keep fluid in and maintain balance. Do you know where I could find a technical diagram that shows the make-up of the fan clutch?

More or less - but the change in the viscosity of oil is due to long-chain polymers. When it gets hot, the chains bond together, and make the oil thicker. When cold, the chains break apart, and the oil gets effectively thinner. Either way, tho, the oil will thin as it heats - it just thins less.

This fluid works the other way - it get physically thicker when heated, and it doesn't have the viscosity reduction that you find in multi-grade engine or gear oil. That's the sticking point - and I don't think any of the fan clutch makers are likely to give with what they use (although I'll probably ask, sooner or later.)

As far as technical drawings, I haven't seen any yet, and I haven't had occasion to make any. However, it's probably a vaned rotor inside a stator chamber (maybe vaned as well - I haven't cut into one yet) with the vanes acting to encounter the resistance of the viscous silicone fluid.

I'm certain that the rotor is fairly large, tho, since that's what you "pin" to the case when you "pin" the clutch to make it a mechanical coupling. You are effectively bypassing the viscous fluid in favour of a direct mechanical coupling.

As far as the "e-fan mod," I don't have any trouble with the idea of the thing - I just like having a "string driven thing" going under the hood in addition to an electrically-driven fan. As I learned back in demo - "Two is One, One is None." So much the better if the Two are powered differently.

And, considering the power draw of high-volume fans, I'm inclined to think that the power savings to your engine is negligible (you still have to make electricity to power the thing, don't you?) unless and until I see dyno reports proving otherwise...

5-90

 

[Blaine B.]

Don't you guys think that regular fan clutches are designed well enough, that you don't nee to be testing different oils and such?

 

[5-90]

Don't you guys think that regular fan clutches are designed well enough, that you don't nee to be testing different oils and such?

Well, if they're designed "well enough," why do I have to change mine every three to four years? Gets kinda tiring... It's like First Aid - just because I can do it, doesn't mean I want the practise, y'know?

5-90

 

[rickoregon]

Well, I'm just trying to think of additional ways to improve cooling, especially when other cooling components are becoming less functional between servicing and/or replacement. Seems like the fan is a part to focus on, because more air flow control might provide extra cooling capacity when it's needed.

I'm thinking maybe I can even consider draining all the silicone oil out, installing a grease fitting, and pumping grease inside! LOL Now, that should provide a tight viscous coupling!!

Has anyone tried flex fans (such as flex-a-lite or other brands)?

Those have the advantage of being quiet and producing less drag, because they flex to reduce angle of attack at higher rpm's.

They were popular in the 60's and 70's, I believe.

 

[5-90]

Well, I'm just trying to think of additional ways to improve cooling, especially when other cooling components are becoming less functional between servicing and/or replacement. Seems like the fan is a part to focus on, because more air flow control might provide extra cooling capacity when it's needed.

I'm thinking maybe I can even consider draining all the silicone oil out, installing a grease fitting, and pumping grease inside! LOL Now, that should provide a tight viscous coupling!!

Has anyone tried flex fans (such as flex-a-lite or other brands)?

Those have the advantage of being quiet and producing less drag, because they flex to reduce angle of attack at higher rpm's.

They were popular in the 60's and 70's, I believe.

True - but flex fans tend to actually reduce ram airflow over the radiator at cruise and/or high rpm. Since the fan flattens out at higher speeds (it's a function of air resistance,) you can actually end up presenting a rotating disc to airflow - which will not only cause the fan to not move air, but will actually create a block to airflow.

That's why flex fans aren't in wide use so much anymore. They're made, but anyone who actuallly knows what they're about tends to not use them...

5-90

 

[rickoregon]

Good point, 5-90. However, do they flatten out completely? I thought they just changed pitch slightly in order to reduce the drag on the fan belt at higher rpm's. That would be really strange if they could become completely flat..

Well, I guess it's back to eliminating the fan clutch or increasing the drag somehow (by changing fluid or tweaking the thermo valve..).

Or perhaps I should actually consider an electric fan. I see PartzFinder has a range of high CFM fans that are inexpensive:
http://www.partzfinder.com/SearchResults.asp?Cat=28&Click=790

Has anyone used any of these? Thanks for your ideas. Happy Thanksgiving to you all. Rick

 

[5-90]

If you really want to see a drop in engine temperatures, you might want to consider an engine oil cooler! Not only does the oil have more direct contact with parts getting heated up (like the pistons and valves,) but there is less metal between the oil and the heat, and the oil itself gets heated up by being run in the bearings as well (friction = heat. Lubricant to eliminate/reduce friction will also get heated up...)

Cooling the engine oil should reduce operating temperature noticeably.

Just a thought...

5-90

 

[badron]

Flex fans flatten out at high(er) RPM. DAAA
For most road use a flex fan can work fine. IN GENERAL as RPM increases so does road speed and more air is forced throu the rad. They say: by 35 MPH most cars under normal condition don't need a fan at all.
So under normal concision the flex fan going flat at 35 is fine.
Off roading were we tend to run much slower speeds at a higher RPM the flex fan tend to flatten out when it's needed the most. (bad flex fan) This hold true for towing and any case were the engine is at high RPM but the speed remain low.
So (IMO) flex fans and off roading do not mix.
I like OIL cooler idea! A ENGINE oil cooler MAY keep you auto trany cooler. TRUE or FALSE.

 

[5-90]

Flex fans flatten out at high(er) RPM. DAAA
For most road use a flex fan can work fine. IN GENERAL as RPM increases so does road speed and more air is forced throu the rad. They say: by 35 MPH most cars under normal condition don't need a fan at all.
So under normal concision the flex fan going flat at 35 is fine.
Off roading were we tend to run much slower speeds at a higher RPM the flex fan tend to flatten out when it's needed the most. (bad flex fan) This hold true for towing and any case were the engine is at high RPM but the speed remain low.
So (IMO) flex fans and off roading do not mix.

Half marks. While it's true that at higher speeds you shouldn't need a fan (due to ram air over the radiator,) it's a known fact that every wind must have a "source" (motive force) and a "sink" (place to go.)

So, when the flex fan flattens out and presents a flat surface to the ram air, it actually reduces the "sink" for the wind, and causes the air to "pile up" in front of it. This creates an unusual disturbance to airflow through the radiator core, actually reducing the effect of ram air flowing through. If the flex fan is shrouded, the disturbance to airflow is actually greater, since more of the "sink" is blocked off (either by the shroud or by the fan.)

However, given the relatively high operating temperature of our AMC242 engines (210-215*F) and the low speeds we usually operate at (both crankshaft speed and forward speed) you want as much fan as possible - something else that speaks against using a flex fan...

5-90

 

[rickoregon]

My worry with an oil cooler is the extra components needed and possible overcooling. To keep the oil from becoming to cold I would need to have some sort of thermostat, I suppose. And I think I'd rather improve an existing cooling system, if possible, rather than add a new one. Interesting thought, though. Thanks.

 

[rickoregon]

Oh, another question.. has anyone tried unwinding that helical spring in the front of the clutch a bit? I've read (somewhere) that that prevents the "freespooling" of the fan.