'65 426S Viscous Drive Fan

[Ram Fury]

Lads --
As you might expect, the viscous drive fan on the 426S on my '65 Sport Fury is gone, and probably long gone. Not that I want to have a "concours" car, but the spacer between the water pump and the fan makes it obvious that the mill is missing something under the hood. I've been able to locate a replacement for my car which does not have power steering, but the parts guy did not have any manual steering crank pulleys. He did say a power steering crank pulley would work, just that the outer groove would not be used. Can I just hook up the fan drive to the crank pulley that's still on my car, or do I somehow have dig up a special crank pulley?
Joe Godec

 

[Big_John]

Lads --
As you might expect, the viscous drive fan on the 426S on my '65 Sport Fury is gone, and probably long gone. Not that I want to have a "concours" car, but the spacer between the water pump and the fan makes it obvious that the mill is missing something under the hood. I've been able to locate a replacement for my car which does not have power steering, but the parts guy did not have any manual steering crank pulleys. He did say a power steering crank pulley would work, just that the outer groove would not be used. Can I just hook up the fan drive to the crank pulley that's still on my car, or do I somehow have dig up a special crank pulley?
Joe Godec

Power steering really shouldn't have anything to do with it.

What does matter is the bolt pattern of the fan and water pump, along with the spacing between the water pump pulley and radiator to give you the height of the fan clutches. Measure that and it will make some sense.

My weapon of choice, one I use on my '70 300 and the one I recommend often is a Hayden 2747, https://www.haydenauto.com/media/5485/hayden_low-profile-fan-clutch-flyer.pdf

 

[PH27L7]

Would be nice to see pics of what you have now. Believe your car should have had a steel fan shroud & a seven-blade fan with aluminum blades.

 

[Ram Fury]

Power steering really shouldn't have anything to do with it.

What does matter is the bolt pattern of the fan and water pump, along with the spacing between the water pump pulley and radiator to give you the height of the fan clutches. Measure that and it will make some sense.

My weapon of choice, one I use on my '70 300 and the one I recommend often is a Hayden 2747, https://www.haydenauto.com/media/5485/hayden_low-profile-fan-clutch-flyer.pdf

John --
In 1965, there were two different clutched fans: one was the Thermal Control Drive which sensed the heat from the radiator and engaged the fan if it were needed to pull more air through the radiator; the second was the Torque Control Drive which allowed normal fan operation at slow speeds, but limited the top speed of the fan at those times when you wanted all the horses you could get and by reducing the pull on the fan, there was one power-robbing accessory. The Hayden appears to be the thermal control type, but the one I want is the torque control. These were often grenaded as they were intended for high performance engines during periods of high performance. They're rather hard to come by nowadays.
Joe

 

[Ram Fury]

Would be nice to see pics of what you have now. Believe your car should have had a steel fan shroud & a seven-blade fan with aluminum blades.

PH --
The car still has the fan shroud and the seven-blade fan.
Joe

 

[Big_John]

John --
In 1965, there were two different clutched fans: one was the Thermal Control Drive which sensed the heat from the radiator and engaged the fan if it were needed to pull more air through the radiator; the second was the Torque Control Drive which allowed normal fan operation at slow speeds, but limited the top speed of the fan at those times when you wanted all the horses you could get and by reducing the pull on the fan, there was one power-robbing accessory. The Hayden appears to be the thermal control type, but the one I want is the torque control. These were often grenaded as they were intended for high performance engines during periods of high performance. They're rather hard to come by nowadays.
Joe

Yes, I know that. IMHO, the thermal fan clutch seems to work out better than the non-thermal, but that's just my experience from using them on other cars. Oh well... I'll still recommend that fan clutch.

I have one of these on my '65 300L. fan clutches for sale Yes, it's a non-thermal version. Problem is these aren't being made anymore although you may be able to find one somewhere. Hayden does have some non-thermal versions, but I honestly don't think they spec one that's short enough.

 

[CBODY67]

The thermal and non-thermal fan clutches go in the same place. The correct ones might even ALSO fit my '77 305 Camaro w/factory a/c. What matters is the length of the shaft between the water pump and the fan. As all of the aftermarket-brand clutches now have the slotted water pump flange rather than the "specific-diameter drilled holes" in the water pump flange (like the OEMs used when the cars were new), the same clutch can now apply to non-Chrysler vehicles.

Yes, originally the viscous clutches were the ONLY fan clutch that was available in the earlier 1960s, but when the thermal-control fan clutches (with the external thermostat spring) came out, they were the premium-style clutch and the viscous clutches were relegated to the "low price option" fan clutch.

Typically, like on my '66 and '67 Chrysler 383s, the water pump has one belt that only drives the water pump with ONE belt, as other belts drive the power steering pump, and the alternator and a/c compressor (dual belts with the factory a/c). As there is only one belt dedicated to the water pump, that's why it has the adjustable tension pulley on it.

The viscous clutch only works below a certain rpm level. The thermal-control fan clutch will modulate "in and out" depending upon the heat load the clutch's external thermostat encounters, as needed. Of course, either one will freewheel when the air coming through the radiator exceeds the normal rotational speed of the clutch, under normal conditions.

A radiator that is clogged in the lower half will not dissipate heat in that area, so the clutch thermostat will not lock-up as needed as it "sees" no heat. Might not apply to vertical-flow radiators, but it does with crossflow radiators. FWIW

CBODY67