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FrankieT/A · 03-09-2013, 10:21 AM

Not a good idea to mess with the bi-metallic strip. That is calibrated at the factory, it's made to engage and release at certain temps. In the field we have no real way to test changes with any kind of accuracy.

jonmachota78 · 03-09-2013, 02:19 PM

The Hayden 19" fan that fits these clutches has a 4000 rpm limit. Who makes a safer 19" clutch fan? If its hot and your down to 20% slippage it seems like that could become a problem

Schurkey · 03-09-2013, 02:30 PM

Quote:

Originally Posted by jonmachota78

The Hayden 19" fan that fits these clutches has a 4000 rpm limit. Who makes a safer 19" clutch fan? If its hot and your down to 20% slippage it seems like that could become a problem

That's the RPM of the FAN, not the RPM of the engine. Does your pulley ratio have the water pump running faster or slower than the crankshaft?

Install a heavy- or severe-duty clutch with less slippage, and fan rpm can get out-of-hand in a hurry.

jonmachota78 · 03-09-2013, 06:16 PM

Right, just saying when its hot out and the clutch start to grab, slippage may go down to 20% or maybe more like 15%. Rev the engine to say 5500 rpm and 20% slippage means 4400 rpm at the fan. Yes my crank pulley is larger than the pump pulley so the fan would be spinning north of 4400rpm. Maybe haden is being a little conservative with their 4000 rpm limit? Or maybe that's 4000 rpm sustained when we may only exceed the 4000 rpm fan limit for a few seconds at a time?

FrankieT/A · 03-09-2013, 07:33 PM

By the time the fan reaches terminal speed(the fan lags behind) you are shifting and back below max. Then at the top again and so forth. See it never sees top fan RPM for very long. It can handle it.

LATECH · 03-09-2013, 07:54 PM

Quote:

Originally Posted by FrankieT/A

Not a good idea to mess with the bi-metallic strip. That is calibrated at the factory, it's made to engage and release at certain temps. In the field we have no real way to test changes with any kind of accuracy.

Thank you Frank TA . I will leave it alone. Thanks for testing it out for me.

LATECH · 08:04 PM

Quote:

Originally Posted by Schurkey

That's the RPM of the FAN, not the RPM of the engine. Does your pulley ratio have the water pump running faster or slower than the crankshaft?

Install a heavy- or severe-duty clutch with less slippage, and fan rpm can get out-of-hand in a hurry.

Fan to run slower than crank....larger pulley on water pump than crank.Another good point.

Actually ...I am not sure at the moment. I better look tomorrow. I havent been under the hood all winter , Its been covered with snow.

LATECH · 03-09-2013, 08:00 PM

I am shopping for an aluminum crossflow that will fit. Gotta go out there tomorrow and do some measuring for that. The fan shroud ...well I am going to have to do some measuring for that too. May have to custom fit that.

lust4speed · 03-10-2013, 02:28 AM

So I'm one of those people that can't leave things alone, and I believe that I was the first several years ago to detail how to adjust the spring. Hayden states that they set their clutches to start to engage at 170° air temperature or approximately 200° coolant temp. The key word is "start", and this usually comes out to around 210° for maximum engagement - which I consider too high. Also due to manufacturing tolerances, some clutches come in another ten degrees higher. Here was my original post:

My disclaimer is “results may vary, and try this at your own risk”. I took a new severe duty Hayden clutch fan and re-indexed the valve on the front of the clutch. This fan has the coil thermal spring permanently mounted to the center pin and the outside spring tip dropped into a cast slot where the spring can be lifted out.

The pin controls the fluid coupling. As the pin is rotated counter-clockwise, the fan engages more. Best way to verify this is to take a hair dryer and apply heat to the coil while the clutch is sitting on the workbench and observe the motion of the center pin as the heat is applied. The object is to have the clutch believe the spring is seeing more heat than it actually is, and the spring needs to be bent to slightly move the center pin in a counter-clockwise direction. Very little adjustment needs to be done and it is easy to over-do the bend. The danger is that the spring could snap off and the fan clutch would be scrap. The actual change needed is to bend the end tang about 5°. Another way to look at it is to make the bend thinking of the minute hand on a clock and move the tip of the tang from 12:00 to about 12:05. First attempt should be not much more than the width of the metal spring. It doesn't take much bending, and it's best to start out with very small changes.

Moving the tip of the tang clockwise results in the main spring body moving counter-clockwise which is where it needs to be to engage earlier. When I got my A/C working the coolant temp was staying right where the fan engaged, so by making the fan come on sooner, the coolant temp dropped to the new level.

LATECH · 03-10-2013, 09:55 AM

Thanks Lust for speed. I was reading through the older threads last night and saw your post on the matter.
Excellent info.

FrankieT/A · 03-10-2013, 10:17 AM

As Tom Vaught says, "Engineers do things for a reason". When you start messing with that spring you blow out the calibration. I'm sure it is possible to make slight adjustments. However, when you make an adjustment in one direction you may or may not cause a problem in the other. Now, I'm not saying it can't be done or not be done properly. But, when you start making changes like that you need to be savvy enough to know what affect it may cause somewhere else. As with everything in life; most things are a compromise. If it were that easy our cars would idle smooth as silk and make big power to 9000 RPM. When you start bending that spring, which actually is not a spring but rather a bi-metallic strip. It relies on temperature to turn that shaft back an forth, not spring tension. So by tweaking it, it may not have the reach (not tension) to go back the other way enough, thereby not doing what it is intended to do. JMO

72LuxuryLeMansLa. · 03-10-2013, 11:59 AM

Quote:

Originally Posted by FrankieT/A

As Tom Vaught says, "Engineers do things for a reason". When you start messing with that spring you blow out the calibration. I'm sure it is possible to make slight adjustments. However, when you make an adjustment in one direction you may or may not cause a problem in the other. Now, I'm not saying it can't be done or not be done properly. But, when you start making changes like that you need to be savvy enough to know what affect it may cause somewhere else. As with everything in life; most things are a compromise. If it were that easy our cars would idle smooth as silk and make big power to 9000 RPM. When you start bending that spring, which actually is not a spring but rather a bi-metallic strip. It relies on temperature to turn that shaft back an forth, not spring tension. So by tweaking it, it may not have the reach (not tension) to go back the other way enough, thereby not doing what it is intended to do. JMO

FrankieT/A,

I used to repair and calibrate Flight Instruments for Helicopters. You would be surprised to know how many adjustments in the world of "Precision Instrumentation" are made by bending this or that just a little and then applying a test signal, be it hot air or electrical current or oil or fluid pressure, and then observe and record the resulting readings until the desired outcome is attained. If a person were to use Mick's method and pay close attention to the rusults there should be little if any problems. JMO

Karl

FrankieT/A · 03-10-2013, 12:13 PM

Quote:

Originally Posted by 72LuxuryLeMansLa.

FrankieT/A,

I used to repair and calibrate Flight Instruments for Helicopters. You would be surprised to know how many adjustments in the world of "Precision Instrumentation" are made by bending this or that just a little and then applying a test signal, be it hot air or electrical current or oil or fluid pressure, and then observe and record the resulting readings until the desired outcome is attained. If a person were to use Mick's method and pay close attention to the rusults there should be little if any problems. JMO

Karl

Agreed, all I'm saying is not to venture out unless you are sure of what you are doing. I'm assuming if you were calibrating helicopter instrumentation, you have the equipment to know what affect your tweaking is doing. You are essentially getting it into range. You will know if you are bending this or that too much, then you can bring it back. Under the circumstances we're talking about it would take a lot of trial and error, which we both know we would not want to be aboard that helicopter. LOL

72LuxuryLeMansLa. · 03-10-2013, 02:46 PM

Quote:

Originally Posted by FrankieT/A

Agreed, all I'm saying is not to venture out unless you are sure of what you are doing. I'm assuming if you were calibrating helicopter instrumentation, you have the equipment to know what affect your tweaking is doing. You are essentially getting it into range. You will know if you are bending this or that too much, then you can bring it back. Under the circumstances we're talking about it would take a lot of trial and error, which we both know we would not want to be aboard that helicopter. LOL

Yeah, I seem to remember something about "We can't just pull over if a problem comes up" or something to that effect.

In Mick's case the hair dryer and thermometer would do for test equipment.

Karl

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