Chrysler guys: Explain Fluid Drive to me!

[Matt Harwood]

We just pulled a 1948 Chrysler New Yorker convertible with an 8 cylinder engine off the trailer this evening. I haven't checked it over or done anything other than drive it into the warehouse, but I did note that it has Fluid Drive. It also has a clutch and a standard 3-on-the-tree shifter. I'm not sure what to expect or how it should drive, but am I correct in assuming that it simply eliminates the need to hold the clutch in when stopped and in gear? Does it make the car feel sluggish like an automatic transmission might or does it otherwise drive like a manual transmission car? Any other tips for operating it correctly?

And man, I really dig the Tartan Plaid interior on these cars. Awesome!

Thanks!

Edited November 20, 2011 by Matt Harwood (see edit history)

[MCHinson]

I am not a Chrysler guy, but until someone who knows these responds, you might want to read this site:

The Fluid Drive torque converter

[Joe Cocuzza]

The shift pattern on a Fluid Drive car has only a reverse position (in and up), a second gear position- low (out and up) and a third gear position- high (out and down). The first gear position was eliminated.

The tranny actually has 4 gears or speeds.

In the out and up gearshift position, which is low, there are 2 speeds and there are two speeds in the out and down gearshift position, which is high.

The clutch is needed to initially engage the trans in any of the gears - reverse, low or high. After that the clutch is only needed to remove it from gear or from going from low to high position while driving.

You can start in either the low or high position.

Example 1:

Put in clutch - put shifter in low position

release clutch - car will idle in gear

give it gas - at about 10-15 mph release gas fully - trans will "clunk" into next gear by itself (you will hear a click or clunk - that is when you know it shifted - takes a second or two)

give it gas again - I am not sure of the speeds to shift, and I am sure someone will chime in on that, but listen to the engine - don't over-rev it

when you are ready to shift into the next gear (high position) - depress clutch and move the gear shifter out and down

Now you are in the 3rd of the 4 speeds

Give it gas - listen to engine revs - release gas pedal and the trans will again shift by itself into the next gear (click or clunk)

Now, in the high gear position you can come to a stop and not have to remove the car from gear - the trans should automatically downshift and then idle. This will put you into 3rd gear and if you are not looking to drag race, you can start off in that gear and do the gas-release-clunk shift into 4th gear.

Or if you are on a slight incline or want to start out a little quicker, when you stop, put the clutch in, and shift the gearshift into the low position and start out as outlined above.

Reverse - use the clutch to move gearshifter to position - release clutch - car will idle in gear - press gas to get car moving.

The Fluid Drive transmission is a bit sluggish, but with the 8 cylinder it will be a little better on takeoff. They are a rock-solid trans but not known for neck-snapping performance.

Hope this helps.

Oh Yeah - to anyone that might reply - if I am not quite correct on some details don't tear me to shreds. I am giving info from my driving experiences with this transmission - not from a manual or book.

[Guest Bob Call]

The Chrysler Corporation fluid drive is a four speed transmission that is electrically shifted. It has a clutch like any other manual transmission, but, additionally has a fluid coupling (not a torque converter). The shifter has the normal first gear position locked out. Driving requires depressing the clutch to put the transmission in gear, There are three shift lever selections. Reverse is in the normal position. In what should be second gear on a regular transmission is low range, and, in what would be third gear on a regulat transmission is high range. Low range is 1st and 2nd gear. High range is 3rd and 4thd gear. For normal driving depress the clutch and place the shifter in high range. The clutch can then be released. To drive depress the accelerator and accelerate to about 15 MPH, release the accelerator and listen for the shift, you can hear it, then depress the accelerator and drive normally. You don't have to use the clutch until you want to change from low range to high range or vice versa or to reverse. If driving in high range you can floor the accelerator and it will downshift to 3rd gear.

These cars are not drag racers and if you want to get on a freeway be sure you have plenty of clearence to get up to speed to merge into traffic.

I had a 50 DeSoto with this transmission and that car was built like a tank and never gave me any trouble.

Edited November 20, 2011 by Bob Call (see edit history)

[c49er]

We just pulled a 1948 Chrysler New Yorker convertible with an 8 cylinder engine off the trailer this evening. I haven't checked it over or done anything other than drive it into the warehouse, but I did note that it has Fluid Drive. It also has a clutch and a standard 3-on-the-tree shifter. I'm not sure what to expect or how it should drive, but am I correct in assuming that it simply eliminates the need to hold the clutch in when stopped and in gear? Does it make the car feel sluggish like an automatic transmission might or does it otherwise drive like a manual transmission car? Any other tips for operating it correctly?

And man, I really dig the Tartan Plaid interior on these cars. Awesome!

Thanks!

Looks to have a 1949 or 50 Chrysler "8" engine in it. Nice looking N-Yorker.

Edited December 17, 2011 by c49er (see edit history)

[Aaron65]

That is a BEAUTIFUL car. I'm jealous. You're a strong man, Matt, picking up those beauties and selling them! On the other hand, you get to experience all kinds of great cars too...

[Rusty_OToole]

Fluid Drive was one of the earliest attempts at making an automatic trans. It is a cross between an automatic and manual, in that it still has the clutch pedal.

It is very simple and ruggedly built. They seldom give trouble. If they do it is usually the wiring and control system, or possibly the trans or Fluid Drive unit low on oil. In either case, very cheap and easy to repair if you know what you are doing.

Shifter, as has been explained, works like this:

Reverse, towards you and up

Low Range, straight up

High Range, straight down

Low Range and High Range have 2 speeds each. Normal driving is done in High Range, Low Range is for starting on a hill, pulling a heavy load or trailer, or slow slogging in sand, mud or snow.

Here is the technique I prefer.

Start the engine and let it warm up. Have hand brake on.

Step on clutch, shift into High Range, release clutch completely. Release hand brake and drive off like an automatic.

When you get going at 14 MPH or more, lift off the gas and the trans should shift into High with a soft *click-clack* from the transmission.

Now go someplace lol.

If you slow down or stop, no need to use the clutch. The trans will shift down by itself. When you take off again, remember to lift off the gas when you want to shift up.

On the highway if you floor the gas pedal the trans will kick down like an automatic, at any speed up to 50.

You can also start off in Low Range for extra power, or slow speed running. Only in Low Range, you shift up at 6 MPH or higher. Same as High Range, just lift off the gas.

To shift from Low Range to High Range or vice versa, step on the clutch and shift the gear lever in the usual way.

To go in reverse, step on the clutch and shift into Reverse.

You can also take off as if it was a manual trans, slipping the clutch, but this can be a little disconcerting because of the extra slippage of the Fluid Drive. Eventually you learn to just dump the clutch, it won't stall. But I find it easier to just shift into gear while stopped, then release the brake and take off for the smoothest takeoff.

For a look at some original Chrysler service manual look in the technical section of the Imperial owners club.

The subject of operating and maintaining the Fluid Drive and transmission have been covered in depth in the CHrysler and Dodge sections of this web site. There were some long threads in around 2008 that will tell you all you need to know.

Edited November 21, 2011 by Rusty_OToole (see edit history)

[Guest another Ratman]

I just purchased a original vintage brochure published by Chrysler explaining fluid drive (Prestomatic). It's entitled " Chrysler's Prestomatic Fluid Drive Transmission" published by the Chrysler Sales Division Detroit Michigan. This transmission came out in 1938. The brochure was published in 1950. Check with pjsautolit. or ebay item number 230638195241 I paid 8.00 plus 5.00 shipping. A really good item to have. great color drawings and explanations. UPDATE... I use the date 1938 only because Chrysler printed it on the booklet. 1938-1950. It refers to 1938-1950 as Fluid Drive.

Edited November 22, 2011 by another Ratman (see edit history)

[Guest De Soto Frank]

Most the the previous respondents have described the gear-change and operating sequence correctly.

A few points of clarification, as Chrysler Corp. painted lots of their products with the same "Fluid Drive" brush....

The original "Fluid Drive" that was introduced on the 1939 Chrysler - De Soto -Dodge was a straight "1-to-1" fluid coupling - there was no torque multiplication whatsoever. The Fluid Coupling was bolted directly to the crankshaft, replacing the traditional flywheel. Behind it was a regular single-disc clutch and 3-speed transmission, which could be optioned with an Overdrive.

In 1941, Chrysler Corp introduced their first semi-automatic transmission - the M-4 "Simplimatic" / "Vacamatic", which was a four-speed sliding-gear transmission, divided into two forward driving ranges, plus reverse. Automatic up-shifts were achieved by a system of centrifugal governor switch, relay, solednoids, and a vacuum-servo. Down-shifts were achieved by spring tension. Any time the shift lever was used, the clutch had to be depressed.

This transmission was offered only on Chrysler 6 and De Soto in 1941 & '42. The Chrysler Eight in '41 had a different version which was the Fluid Coupling and 3-speed OD transmission.

In 1946, Chrysler Corp. refined the semi-automatic, replacing the vacuum servo with an internal oil-pump and hydraulic up-shift system. This version was known officially as the M-5 "Hydraulically-operated Transmission". This version was offered only on Chrysler, De Soto, through 1948.

In 1949, the semi-automatic gearbox received it's final upgrade, revising the control system to eliminate the control relay. This version is the M-6 Hydraulically-operated transmission was continued through 1953 or '54, when it was finally replacd by the Powerflite 2-speed automatic transmission.

Now, the Fluid Coupling, which was essentially the same 1-to-1 direct coupling from 1939 through 1951, was revised in 1952 to become a true "Torque-converter", which did have torque-multiplication properties. Chrysler Corp. called this new driveline component "Fluid-Torque Drive; some versions had a self-contained sump and oil pump, while others utilized engine oil and oil pressure. While this was a great improvement to try to capitalize on the wonderful new Hemi V-8s, it was still backed-up by the stodgy and "clunky" M-6 semi-automatic tranny, which still was not capable of upshifting under load or acceleration... you still had to take your foot off the gas and "wait for the clunk"... and use the clutch whenever you moved the column selector.

The most important thing to bare in mind, is that any versions of the Chrysler semi-automatic transmission are a manual sliding-gear transmission, equipped with some sort of self-shifting device, not entirely unlike Hudson's "Drivemaster" or Packard's "Electromatic Drive".

They are in no way an "automatic transmission" in the contemporary sense... "true" automatic transmissions employ a system of bands, clutches and planetary gears, like the Model T Ford... with the addition of a torque-converter and an automatic shifting department.

True automatic transmissions are capable of upshifting under load and acceleration.

When learning to drive a Chrysler semi-automatic, it is best to lift your foot completely off the accelerator while waiting for the shift... you'll know when it has occured, because the car will slow noticeably against engine compression after the upshift has happened - the low-speed in either range "free-wheels", and the car will just coast. Once the transmission has upshifted, you can then gently apply the accelerator.

Another tip- make sure the engine idle-speed is not set too-high... 400-450 RPM is best. If the engine cannot idle down this far, upshifts may be delayed or not occur at all.

While it was not the most efficient driveline system in terms of performance, it was a heavily-built and well-engineered system, and many have functioned flawlessly for more than 100,000miles...

That Highlander you have there is a nice car... enjoy driving it !

[Guest Mark Rigotti]

We just pulled a 1948 Chrysler New Yorker convertible with an 8 cylinder engine off the trailer this evening. I haven't checked it over or done anything other than drive it into the warehouse, but I did note that it has Fluid Drive. It also has a clutch and a standard 3-on-the-tree shifter. I'm not sure what to expect or how it should drive, but am I correct in assuming that it simply eliminates the need to hold the clutch in when stopped and in gear? Does it make the car feel sluggish like an automatic transmission might or does it otherwise drive like a manual transmission car? Any other tips for operating it correctly?

And man, I really dig the Tartan Plaid interior on these cars. Awesome!

Thanks!

Matt,

Actually it is a six speed if it is like my '49 Saratoga. In and up is reverse - Forward and up is LOW - Forward and down is HIGH. You need to clutch between each of these. Now there is an overdrive associated with each. To go into overdrive you let off the gas and you will hear a clunk (thus the phrase clunk o matic which is associated with these gems) add a bit of gas and now you are in the associated overdrive. So for normal driving clutch to low - foot off gas and like magic you are now in low overdrive - clutch to high and finally foot off gas and now you are in high overdrive. These things have many names Presto-matic, Semi-Automatic, Clunk-omatic, Fluid drive, etc. They do ride well.

Now if anyone can explain to me a overdrive for reverse I'd greatly appreciate it. I've never dared to try it but rumour has it it does exist.

Regards,

Mark Rigotti

[Guest De Soto Frank]

Hi Mark,

Slight correction to your post...

While the function of the Chrysler semi-automatic may seem like a conventional 3-speed plus overdrive, the internal construction of the 1941-'53 MoPar sem-autos is different.

It is a sliding-gear four-speed transmission with an auto-matic shifting system incorporated into it. Top gear (Hi-range, after automatic up-shift) is actually direct drive: the driveshaft speed is equal to the input shaft speed.

A true "manual plus overdrive" transmission in this era, is a conventional three-speed manual shift transmission with a planterary -gear auxiliary transmission tagged on behind it, which increases the driveshaft speed approximately 30% over input shaft speed.

There is usually an over-running clutch in both the semi-auto and the OD, when in the lower range, which allows the driveline to free-wheel when coasting, and would not drive the car if put into reverse.

The confusion started even back in the first days of the Chrysler & De Soto semi-automatics in 1941, when some sources started referring to the system as "Under-drive"...

Yes, I'm nit-picking here, but I feel it is important for folks to know the difference between Chrysler semi-automatics, and ... everything else...

Edited December 17, 2011 by De Soto Frank (see edit history)

[Guest Skyking]

Wow, this thread brings back memories. When my older brother had his Atlantic station back in the sixties we had a 51 or 52 Dodge with the fluid drive that we used to pick up parts. Different car to drive for sure. Wish we kept it. It was in mint condition back then.

[Aaron12345]

I'm looking g for a shift know for my m6 transmission starring colum. Any one know where I can find one ?

[TerryB]

Are you looking for a shift knob?

[JACK M]

The plastic and pot metal on those cars didn't survive the ravages of time very well.

[Hemi Dude]

On 12/16/2011 at 8:21 PM, Guest De Soto Frank said:

Hi Mark,

Slight correction to your post...

While the function of the Chrysler semi-automatic may seem like a conventional 3-speed plus overdrive, the internal construction of the 1941-'53 MoPar sem-autos is different.

It is a sliding-gear four-speed transmission with an auto-matic shifting system incorporated into it. Top gear (Hi-range, after automatic up-shift) is actually direct drive: the driveshaft speed is equal to the input shaft speed.

A true "manual plus overdrive" transmission in this era, is a conventional three-speed manual shift transmission with a planterary -gear auxiliary transmission tagged on behind it, which increases the driveshaft speed approximately 30% over input shaft speed.

There is usually an over-running clutch in both the semi-auto and the OD, when in the lower range, which allows the driveline to free-wheel when coasting, and would not drive the car if put into reverse.

The confusion started even back in the first days of the Chrysler & De Soto semi-automatics in 1941, when some sources started referring to the system as "Under-drive"...

Yes, I'm nit-picking here, but I feel it is important for folks to know the difference between Chrysler semi-automatics, and ... everything else...

Hi Guys, the original question asked "Explain Fluid Drive to me."  Well, fluid drive is basically what we have read already but in the simplest form, here it comes;

A fluid coupling looking like a torque converter, but with no torque multiplication, bolted to the crankshaft of 6 or 8 cylinder engine in some MOPAR. On the output side is the manual clutch and pressure plate. Behind this is a normal, everyday 3 speed transmission with reverse. The Dodge was the model that had this simplest setup. You could drive the car EXACTLY as you would a normal 3 speed stick shift car. Performance this way was very close to any other car without fluid drive, maybe a little slower, but the benefit was in stop and go traffic where the driver would have the left leg getting a real workout engaging and disengaging the clutch pedal to move a few feet at a time. With Fluid Drive, I would leave the transmission in 2nd gear and just leave the clutch engaged and work between the gas pedal and the brake to stop. At standstill, the engine was ready to move the car by releasing pressure on the brake and just a little gas and you moved forward. Even if the speed would increase to 20 or 25 MPH, 2nd gear was fine, then when traffic slowed or stopped, just apply the brake and come to a full stop. The engine was happy and so was the driver.

That is Fluid Drive in it's basic form. When Chrysler came out with the 331 CI HEMI in 1951, they had a torque converter in front of the M6 transmission which was the pinnacle of that operating system, I had that setup in my 1951 Imperial. That was a fast car if you knew how to use and shift the gears from 1st to second and then to 4th. That HEMI was a great engine right from the 'Get-Go."

This is a photo of an Imperial at Carlisle, mine was Light Blue and long gone. Maybe someone here owns this car?  That would be 'COOL'

[Fleetwood Meadow]

Correct me if I’m wrong, but the electronic solenoid version with the 2 low speeds and 2 high speeds was called the gyro-matic and the 3-speed was called the fluid drive. Or is Chrysler and Dodge different at that time? My ‘51 Dodge Meadowbrook is a 3-speed fluid drive. It uses no electronics in shifting. It has a very low, 0-10mph gear, a 2nd, 10-25mph gear, and a high, 25+mph gear.  You need to shift from gear to gear but that is the only time for the clutch. I generally shift to 2nd when I stop but I can leave it in 3rd gear all day without using the clutch. I find it has the pick up of a manual with the convenience of an automatic. And the luxury of not being able to stall it. 

[Ron42Dodge]

On 2/28/2022 at 4:06 AM, Fleetwood Meadow said:

Correct me if I’m wrong, but the electronic solenoid version with the 2 low speeds and 2 high speeds was called the gyro-matic and the 3-speed was called the fluid drive. Or is Chrysler and Dodge different at that time? My ‘51 Dodge Meadowbrook is a 3-speed fluid drive. It uses no electronics in shifting. It has a very low, 0-10mph gear, a 2nd, 10-25mph gear, and a high, 25+mph gear.  You need to shift from gear to gear but that is the only time for the clutch. I generally shift to 2nd when I stop but I can leave it in 3rd gear all day without using the clutch. I find it has the pick up of a manual with the convenience of an automatic. And the luxury of not being able to stall it. 

Dodge, DeSoto and Chrysler all had the Fluid drive advertised on the trunk which really only was promoting the ability to stop without pushing in the clutch.  The Chrysler and DeSoto had the early automatic shifts which had various names like tip toe shift, Vac Amatic etc, which were part of the transmision, not part of the fluid drive.  Kind of like saying it had a fluid drive engine.  No it didn't.  I describe the fluid drive as a forgiving Clutch as it is more difficult to kill the engine when starting out.  But it is only atached to the clutch and not part of the clutch.  All the fancy names were usually refering to the transmission, not the fluid drive.

[De Soto Frank]

On 2/28/2022 at 5:06 AM, Fleetwood Meadow said:

Correct me if I’m wrong, but the electronic solenoid version with the 2 low speeds and 2 high speeds was called the gyro-matic and the 3-speed was called the fluid drive. Or is Chrysler and Dodge different at that time? My ‘51 Dodge Meadowbrook is a 3-speed fluid drive. It uses no electronics in shifting. It has a very low, 0-10mph gear, a 2nd, 10-25mph gear, and a high, 25+mph gear.  You need to shift from gear to gear but that is the only time for the clutch. I generally shift to 2nd when I stop but I can leave it in 3rd gear all day without using the clutch. I find it has the pick up of a manual with the convenience of an automatic. And the luxury of not being able to stall it. 

Simplest way to ID whether a "Fluid Drive" MoPar actually has a semi-automatic transmission is to depress the clutch and CAREFULLY try to go through the "H" Shift Pattern.

On Semi-Automatic cars, the column lever will NOT go into "First gear position" (pull towards the rim of the steering wheel and down towards the seat).  The three lever positions are "Lo Range" (2nd gear/ towards the dash & up),  "Hi Range" (3rd[High] gear/ towards the dash and down towards the floor), and "Reverse" (Pull towards the steering wheel and up, just as it with plain old three-speed).

If the column lever will go into ALL FOUR positions of the "H pattern" (including "towards the steering wheel and down"/ "First Gear"),  then your MoPar has plain old three-speed manual transmission, regardless of whether it has a Fluid Coupling in front of it.  Further clues are electrical terminals & wiring on the carburetor itself.

When you are operating a MoPar equipped with Fluid Coupling, the only time you MUST use the Clutch pedal, is when you are moving the Column Lever to a new position.

Chrysler Corp. confused a LOT of people by slapping "Fluid Drive"  liberally over so many of their products.  It was their "Floating Power" ad slogan of the 1940's.

 

[Peter Gariepy]

 

[Peter Gariepy]

 

[Peter Gariepy]

 

[Peter Gariepy]

https://en.wikipedia.org/wiki/Fluid_Drive

 

[Ron42Dodge]

18 hours ago, De Soto Frank said:

Simplest way to ID whether a "Fluid Drive" MoPar actually has a semi-automatic transmission is to depress the clutch and CAREFULLY try to go through the "H" Shift Pattern.

On Semi-Automatic cars, the column lever will NOT go into "First gear position" (pull towards the rim of the steering wheel and down towards the seat).  The three lever positions are "Lo Range" (2nd gear/ towards the dash & up),  "Hi Range" (3rd[High] gear/ towards the dash and down towards the floor), and "Reverse" (Pull towards the steering wheel and up, just as it with plain old three-speed).

If the column lever will go into ALL FOUR positions of the "H pattern" (including "towards the steering wheel and down"/ "First Gear"),  then your MoPar has plain old three-speed manual transmission, regardless of whether it has a Fluid Coupling in front of it.  Further clues are electrical terminals & wiring on the carburetor itself.

When you are operating a MoPar equipped with Fluid Coupling, the only time you MUST use the Clutch pedal, is when you are moving the Column Lever to a new position.

Chrysler Corp. confused a LOT of people by slapping "Fluid Drive"  liberally over so many of their products.  It was their "Floating Power" ad slogan of the 1940's.

 

Great explaination.  I did not know the floating power refered to the Fluid drive.  I always assume it was a reference to the ride / suspension.

 

[Gunsmoke]

"Floating Power" was a phrase Chrysler used as an advertising ploy beginning in 1931/32 for many of their models including Plymouth. As I understand it, their engines prior to then were typically bolted solidly to the frame, using only vulcanized rubber mounts and the engine acted as a stiffener for the whole chassis as well. But vibration and "engine induced tremor" caused customer complaints. So Chrysler modified the drivetrain, X braced the frame for stiffness, and used a 3 point engine suspension system that allowed it to hang free of direct bolting to chassis (some Chrysler experts may have a tidier explanation). In any event rather than admit the problem with their old system, they coined the phrase "floating power" as some new creation, and said it eliminated engine tremor, when in fact it was simply correcting a vibration issue! I don't know that they ever meant the term to apply to the transmission (like fluid drive), but perhaps they used it for that purpose in later years.

[Studeous]

I came for the fluid drive, but spent some time admiring the seat coverings. Snazzy.

Edited May 22, 2022 by Studeous (see edit history)

[Rusty_OToole]

There is some confusion around the meaning of Fluid Drive and the various transmissions used on Chrysler products 1939 -1953. The Fluid Drive unit refers to the fluid coupling only. It  was used with various transmissions. The layout was like this:

 

Engine - Fluid Drive unit - dry plate clutch - transmission. All Fluid Drive cars used this layout and these parts. They differed only in transmission.

 

There were 3 or 4 different transmissions. First was a manual shift 3 speed used on early cars and on some later Dodge and Plymouth models. Then there was a vacuum shift self shifting 4 speed. Then the most commonly seen, hydraulically shifted 4 speed.

 

A late variation was the Fluid Torque Drive. In this case, a torque converter replaced the Fluid Drive unit. A torque converter is a more complex fluid drive. The fluid drive provides slippage, a torque converter multiplies torque  like a gear set. The torque converter requires a separate oil supply. In some cases there was a separate oil pan under the torque converter, in others the torque converter shared the engine oil supply. Torque converters were available as an option on Chrysler and Imperial 1951 52 and 53, may have been standard equipment on the more expensive models. Also used on the 1954 Plymouth HyDrive.

 

 So if you want to be totally accurate the fluid drive and transmission are 2 different things.

[De Soto Frank]

On 5/22/2022 at 11:10 AM, Ron42Dodge said:

"Great explaination.  I did not know the floating power refered to the Fluid drive.  I always assume it was a reference to the ride / suspension."

"Floating Power" only refers to the rubber mounting cushions Chrysler began using on their vehicle drivetrains beginning in the early 1930's.  It has nothing to do with anything else on the vehicle. 

Once introduced, Chrysler Corp. made a big marketing deal out of "Floating Power" (some would call it a gimmick), and used the term liberally in their marketing materials, and even stenciled it on their speedometer dials for a while in the 1930's.


Chrysler Corp did the same sort of thing with "Fluid Drive" starting in 1939, and used the term liberally, and in ensuing years created a lot of confusion.

I probably shouldn't have mentioned "Floating Power" in this discussion; I was simply trying to illustrate how technological developments can get abused and overused by the marketing dept.


Sorry if I muddied anyone's water... 

Frank

 

 

 

[De Soto Frank]

Rusty clarified it pretty well.

[mrspeedyt]

I had two 1941 de sotos with the simplematic fluid drive. The later versions were much better because the 1941 had like a ratchet device overdrive in both the low range and the high range which gave you first and third gears if the ratchet mechanism wasn't prematurely worn out.

This was a problem with the early transmissions like my 41 DeSotos. There was a knob similar to a overdrive knob that you could pull out and do away with the ratchet mechanism that allowed you first and third. So in other words, in the low range position you'd have second gear and in the high range you would have fourth gear without the worn out ratchet mechanism messing things up. The fluid drive would allow you to drive the car without the clutch once you were in either the low or the high range. On flat land I could literally keep the car in high range and the fluid drive would allow me to accelerate from a stop slowly up to highway speed in the top (fourth) direct gear. That early attempt in 1941 was actually a piece of s*** transmission when it had a number of miles on it.

Edited May 23, 2022 by mrspeedyt (see edit history)

[Ron42Dodge]

9 hours ago, mrspeedyt said:

I had two 1941 de sotos with the simplematic fluid drive. The later versions were much better because the 1941 had like a ratchet device overdrive in both the low range and the high range which gave you first and third gears if the ratchet mechanism wasn't prematurely worn out.

This was a problem with the early transmissions like my 41 DeSotos. There was a knob similar to a overdrive knob that you could pull out and do away with the ratchet mechanism that allowed you first and third. So in other words, in the low range position you'd have second gear and in the high range you would have fourth gear without the worn out ratchet mechanism messing things up. The fluid drive would allow you to drive the car without the clutch once you were in either the low or the high range. On flat land I could literally keep the car in high range and the fluid drive would allow me to accelerate from a stop slowly up to highway speed in the top (fourth) direct gear. That early attempt in 1941 was actually a piece of s*** transmission when it had a number of miles on it.

Part of this whole conversation has been trying to set straight what Fluid drive was.  It was not part of the transmission and had nothing to do with shifting.  It was a one to one torque converter located between the engine and clutch that allowed you to come to a full stop while in gear.  You could also start from a stop without having to use the clutch.  The tranmisiion type handled the automatic or manual shifting depending on whether you had a Chryler, DeSoto or Dodge and later Plymouth.  Too many folks think the fluid drive is part of the transmission but it is not.

Edited May 24, 2022 by Ron42Dodge (see edit history)

[De Soto Frank]

Ron 42,

I hate to tell you, but I think you may have muddied the waters too (inadvertently)....

The top photo is the original "Fluid Drive" Fluid COUPLING.  It is a "1 to 1" fluid coupling, no torque multiplication, nothing gets "converted".

The lower photo is (probably?) a MoPar "Fluid Torque Drive" unit, which IS indeed a torque converter.  It appears to be the version that shared oil with the engine.

They are NOT the same thing.

The Fluid Torque Drive was one more step along Chrysler's way towards a fully automatic transmission.

It was developed to improve driveability with the fabulous new Hemi engines....


 

[Ron42Dodge]

On 5/25/2022 at 12:59 PM, De Soto Frank said:

Ron 42,

I hate to tell you, but I think you may have muddied the waters too (inadvertently)....

The top photo is the original "Fluid Drive" Fluid COUPLING.  It is a "1 to 1" fluid coupling, no torque multiplication, nothing gets "converted".

The lower photo is (probably?) a MoPar "Fluid Torque Drive" unit, which IS indeed a torque converter.  It appears to be the version that shared oil with the engine.

They are NOT the same thing.

The Fluid Torque Drive was one more step along Chrysler's way towards a fully automatic transmission.

It was developed to improve driveability with the fabulous new Hemi engines....


 

Thanks Frank.  I removed second picture.  I will see if I can find a better image.

[61polara]

As you can see from the above posts, driving a fluid drive with the semi-automatic transmission is very flexible with many variations.  Overall, think of it as an automatic, but one where you have three steps to put it in gear.  One, depress the clutch, two, put it in gear, three, release the clutch.  Release the clutch while you are standing still, then accelerate.  The Fluid Drive clutch disc is not meant to be slipped for starting.  It is a rather small clutch and you can wear it out prematurely by slipping it to start every time.  On the other hand, using the clutch in backing or close maneuvering is fine and give more precise control of the motion.

[c49er]

Here is a 1941-53 Fluid drive coupling cut open...plain and simple..two grape fluid halves.

One half spinning in fluid forcing the other half in the same fluid to spin.

No torque multiplication.

View from under bell housing showing fluid drive coupling with clutch attached.

View of 1949-53 M-6 Hydraulic trans attached to FD coupling.

 

Edited May 27, 2022 by c49er (see edit history)

[De Soto Frank]

19 hours ago, Ron42Dodge said:

Thanks Frank.  I removed second picture.  I will see if I can find a better image.

Ron, I'm not trying to beat-up on you... it is a VERY confusing subject, and MoPar didn't help our understanding by slapping ""Fluid Drive" on everything... 😵

[Rusty_OToole]

If you want to know what one looks like, here it is in gory detail. Notice that there are 3 separate units, the Fluid Drive, dry plate clutch, and manual transmission. Other models used a similar transmission that shifted itself using a little hydraulic cylinder and pump.

 

 

 

Edited May 27, 2022 by Rusty_OToole (see edit history)