Fluid Drive Vs. Fluid Torque Drive

[keithb7]

I am studying the two, to try and get it right in my mind. Am I on the right track here?

 

A fluid drive is an oil filled fluid coupler. Right? A fluid coupler is not a torque converter.  To the average Joe is may appear to be a torque converter, but it does not manipulate the torque.

A Fluid Torque Drive system utilizes a proper torque converter. It is like the earlier fluid coupler with the addition of 2 stators and curved turbines. The stators and curved turbines offer torque multiplication, correct? The stators spin on over-running clutches that allow them to spin freely when no torque multiplication is required. Driving flat on the hi-way for example at cruising speeds. When a hill adds load on the engine and slows down car speed, torque manipulation again begins. Am I on the right track here? The simple fluid drive does not offer these benefits. The torque converter offers larger variation of  torque, which is why I can drive around in my Fluid Torque Drive equipped 1953 Windsor deluxe in high gear range all the time.  Some questions:

 

Does the fluid drive run at cooler temps? I suspect yes. Does the fluid drive have any cooling for the fluid drive oil?

Does the fluid torque drive with proper torque converter, run at higher temps due to the oil changing direction within the stators? Sitting at a street light with clutch engaged and foot brake holding car stopped, and transmission, does this cause increased heat in the torque? If left in this condition for considerable time, say waiting for a slow train that stops and backs up, on a hot summer day, will the torque heat up considerably? I assume there is no real way to know what your torque temp is, or if it got pretty hot.  Smell of burnt oil maybe when draining torque oil. On engine-fed TC, I assume engine coolant could also get pretty hot in this situation also. No?

 

I have never driven the fluid drive. I'd be interested in experiencing it compared to my Fluid Torque Drive unit. 

Your comments are appreciated.

[Gregarious13]

The simple answer: 

 

A fluid coupler (Fluid Drive) also known as a viscous coupler transfers torque from the drive to the driven shaft.

 

A torque converter will multiply the input torque at low speeds, effectively becoming a reduction gear. Torque converters commonly have a lockup clutch that mechanically connects the input and output when speeds are equal to avoid loss of torque.

 

I imagine there is very little heat buildup from the fluid drive compared to the torque converter. Leaving the fluid drive engaged for long periods of time should not harm anything.

[Dodgeb4ya]

There are cooling fins on the coupling. Inside looks just like a grapefruit.... straight fins..

Here's the inside of one I cut apart....

I used to work on them all the time.

[keithb7]

Thanks for the pics @Dodgeb4ya. Your pics are of a fluid drive, correct? No torque multiplication as there are no stators and turbines. Am I right here?

I recently had someone question me on the visual differences between the Fluid Drive, and the Fluid Torque Drive.

I believe the Fluid Drive is a totally sealed unit. By '53 the Fluid Torque Drives seemed to have external cooling. Am I correct to state that?

The V8's Fluid Torque Drives had a torque oil sump pan under the bell housing area. Also an oil cooler on the front of the engine near the water pump. Torque oil was fed to and from the front cooler via external oil lines.

 

The Fluid Torque Drive model in my 6 Cylinder Windsor has the Engine-Fed oil option. The torque oil is shared with the engine oil and also cooled this way. When my engine oil is drained I also drain my toque oil. I believe this also proves that I had a Fluid Torque Drive. Not the sealed Fluid Drive option.

 

Am I on the right track here? Thanks, Keith

[Dodgeb4ya]

Yep the pics are of a Fluid Drive coupling.

 The six cylinder FTD's have cooling fins on the converters...no other cooling.... that's the only way I've seen them.

On the chrysler V8's... late 51 and up on the cars I've had they all had or have the sump with the cooler bolted to the left front of the engine block... not engine fed.

Dodge DeSoto and Plymouth are all engine fed I believe sixes and eights... not 100% sure on that though.