Fluid drive

[dodgeguy]

O.K. so I asked you guys before about this subject, took some flak because you say it has been covered, but I can't find it!  Here goes, what weight and spec oil goes in the fluid drive( coupling) portion of my 47 d24? Some one suggested the service manual, but all it says is use genuine Mopar Fluid Drive oil ! any ideas? help?

[DonaldSmith]

I bought some hydraulic fluid from Tractor Supply.  Lemme (Forumspeak for "Let Me") run out to the garage to see what it is. 

 

"Traveler Premium Universal Tractor Trans/Hydraulic Fluid".  

 

I couldn't find more info under the search, but I remember something about "Type 32".  

[Don Coatney]

Fluid Drive
 
Fluid Drive was a $25.00 option available on the Doges, DeSotos and Chryslerss. Besides the cool looking Fluid Drive script on your rear deck, what did you get? Fluid Drive is a torque converter, that is, it converts engine torque and transfers it to the transmission via a fluid medium. The idea is simple. Imagine two electric fans facing each other. If you turn on one fan the air pressure created will cause the blades of the facing fan to spin. In this example, the fluid medium is air. The Dodge Fluid Drive works in a similar manner. The torque converter coupling is bolted to the flywheel. Inside the torque converter coupling are two "fans" facing each one another. The entire torque converter is filled with a special fluid. As the engine turns one set of fan blades (called vanes) is driven, forcing the fluid against the vanes of the facing unit. This causes that unit to turn which drives a standard clutch and pressure plate assembly. The power is then transmitted down the drivetrain to the rear wheels just like the standard drivetrain. The advantage of Fluid Drive is there is no direct mechanical connection between the engine and drive train. This translates into a very smooth power transfer and resulting smooth ride. It also provides some unique and interesting features. For example, to shift into gear you would put the clutch in just like a regular three speed. However if you are idling at a traffic light you can let the clutch out and the car won’t stall! That’s because at idle not enough energy is being transferred from the front vanes to the rear vanes. As you step on the gas the pressure increases and the rear vanes start to spin, transferring energy to the drive train. You would then shift gears like a normal three speed. You can also start in any gear. For example, you could start in third, even though the acceleration would be slow. In some ways, Fluid Drive is like a very simple automatic transmission. The units are essentially maintenance free. The only service requirement is to maintain the correct level of fluid in the torque converter coupling. A special access port is located on the passenger side floorboard on the side of the transmission hump. Remove the access door and bell housing cap. Turn the engine over until the filler bolt lines up. It is a good idea to stuff a rag around the opening so you can drop the filler bolt in the flywheel housing. The service manual recommends using a magnetic socket for the same reason. Be very careful as you fill the unit. Any spillage will always find its way to your clutch disk! After filling, make sure the filler bolt is secure with no leakage. The factory fluid was a Mopar #10 Fluid Drive fluid. Unfortunately this is no longer available. The original fluid was an ISO 32 (10W) with an anti-wear additive and an anti-foam additive which was needed to break up the foam which develops as the vanes turn in the torque converter (Fluid Drive Coupling). The non-foaming characteristics are critical because if air bubbles form the fluid will compress and power can not be transferred. Today, two replacement fluids are readily available. Automatic transmission fluid (ATF) is an ISO 32 fluid. However DEXRON ATF contains a seal swell additive which may swell old seals in Fluid Drives and cause a failure An alternative ATF fluid is Ford Type F fluid. It does not contain the seal swell additive. The best replacement is Universal Tractor Fluid #134. This is an ISO 32 fluid with all the properties of an automatic transmission fluid for wear, heat dissipation, and anti foam. Available at most NAPA stores in 1 and 5 gallon quantities. Obviously if you have a farm/tractor supply outlet nearby they will have it. Universal Tractor Fluid #134 has other positive characteristics including added shear strength for moving bevel cut gears under high loads similar to what is found in the old Fluid Drive transmissions. Many of today’s modern manual transmissions use the #134 fluid, not a gear lube, as the factory fill. The biggest repair problem with Fluid Drive is seal leakage where the transmission input shaft mates into the housing. Any leakage will quickly ruin the clutch disk. Repair kits are available but difficult to find. So are experienced repair personnel. Using the correct replacement fluid can go a long way in extending the service life of your unit. Otherwise the units are factory sealed. Carburetors used on Fluid Drive cars are different than the non-Fluid Drive models. The Fluid Drive adds some drag on the engine and a dashpot is used to slow throttle closing, thus preventing engine stalling. The adjustment of the dashpot and replacement of Fluid Drive seals are addressed in detail in the factory service manual. Lastly the same manual three speed transmission (Type C) is used on both Fluid and non-Fluid Drive applications with one part change. The Fluid Drive transmission has a slightly longer input shaft to accommodate the greater depth of the coupling. The shafts can easily be replaced making a standard 3 speed into a fluid drive version and vice versa.

[desoto1939]

Hey Don:

 

Very nice posting on the Fluid Drive information, always great to read information. My 39 Desoto did not have FD but the 39 Chryslers had that as an option. That is strange because Desoto seemed to be the experimental car for the Chrysler.

 

Rich HArtung

Desoto1939@aol.com

[Don Coatney]

That information was found right here on this webpage in the Resources section. Should be required reading for all forum participants

[James_Douglas]

I really wish the forum master would place this in its entirety into the tech section of the website...that way every couple of years I do not have to paste it into a message again....

 

*****************************************************************************************

 

Technical Note on MOPAR Fluid Couplings
 (Fluid Torque Couplings are NOT covered by this Technical Note. Copy/Publish at will so long as you copy the entire note.)
By James Douglas – San Francisco

 

 

Having run several types of oil in MOPAR “Fluid Couplings” over the years and heard many recommendations, I decided to see if I could approach the issue of what lubricant to use in one of MOPAR’s Fluid Couplings by a more scientific method.

 

As is well known, Chrysler instructed all owners to use “MOPAR Fluid Drive Fluid” only in their Fluid Couplings.  Problem is, MOPAR stopped making it decades ago.

 

My first stop was Chrysler Historical.  After a month of looking, I was told that they do not have any of the original engineering information as to the specifications of the fluid.

 

Then I headed off into internet land to hunt down anything I could find on the subject from ORIGINAL sources.  I managed to find an original Chrysler Question and Answer sheet from 1939 about fluid drive from Chrysler Engineering.  In it they stated:

 

“…The proper fluid is a low viscosity mineral oil, which also servers to lubricate the bearing enclosed in the coupling. The pour point is such that the oil will pour at the lowest anticipated temperature, and has no corrosive effect on the steel parts of the unit.”

 

All well and nice, but not enough to figure out exactly what they used as fluid.  Later in the same document they talk about the types of metal used and the carbon-graphite seal.  Hum, carbon-graphite seal. 

 

I did some more digging for a few months and turned up a can of unopened original MOPAR Fluid Drive Oil.

 

An analysis of that oil, and some more literature I ran across, stated that the original fluid was a pure-base mineral oil with a Saybolt Viscosity of between 100 and 150. The fluid had a Viscosity Index of greater than 80.

The fluid had anti-foaming and anti-oxidation additives. It specifically did NOT have any seal swelling agents as these can attack the carbon-graphite seal and the copper in the bellows. This last specification eliminates most modern transmission fluids.

After finding several formulas to convert Saybolt Viscosities to Kinematic Viscosities, it appears that the best match to the original specification is ISO 22 or ISO 32 oil.

However, the ISO 22 is just below 100 Saybolt and the ISO 32 is much higher than 100 Saybolt.

Based on a period (c.1947) Lubrication Industry article on fluid couplings that had the following admonishment:

“Contrary to popular supposition any attempt to use a higher viscosity fluid would actually reduce the torque transmitting ability of the coupling since torque-transmission is dependent upon a high circulation of fluid between the impeller and runner and is not caused by any viscous drag between the two.”

 

During my continued research on the history of the Fluid Coupling, I ran across the fact that the original company that licensed the fluid coupling technology to Chrysler is still in business and still making fluid couplings for industrial applications. 

 

After a couple of weeks of digging, I found a senior engineer from that company that would have a long technical talk with me on fluid couplings.   In essence, he agreed with the period information I quoted above.  He added that the lowest viscosity oil that would still provide for bearing lubrication is the one to use in theory.  However, he did say that unless the fluid coupling bearing has been replaced and is know to be very high quality then err on the heavy side viscosity wise.  Just don’t over do it, he stated.

 

I was also told that normal hydraulic fluid does not have large amounts of anti-foaming agents in them as they usually do not have large amounts of air in the systems to foam in the first place. 

 

A fluid coupling is only filled to 80% and as such has lots of air in it.

 

Therefore, when looking for fluid coupling oil, one must look for an oil that is a “Circulating Oil” which has a lot of anti-foaming additives in it.

 

I was also informed that the additives tend to have a shelf life in the can, or in use, of 5 to 7 years and it should be changed at that time.

 

I was also told that the couplings are actually somewhat permeable and water vapor will work its way into and then back out, when hot, of a steel fluid coupling. Very little amounts, but apparently is does go on.

 

I was also told to never use engine oil or ATF as both would cause problems in the long run.

 

Based on the research and discussions I have come to the conclusion that ISO 32 hydraulic oil with the proper additives and VI (Viscosity Index) above 80 is a suitable replacement for the original MOPAR fluid drive fluid. ISO 22 would be a better exact match, but only if the quality and condition of the bearing is know in a particular coupling.

The oil I have identified that meets the specification, with a higher general viscosity to deal with the age of the bearings, is: Mobile DTE light circulating oil ISO 32. This oil is available at Granger. 

 

I have run this oil for about six months in San Francisco city traffic as well as up steep mountains on very hot days.  The coupling works well.  I have noticed, and other car people have as well, that the car seems to move out from a dead stop to 10 MPH better with the fluid.  Only a before and after session on a dynamometer would tell for sure, but I feel that it moves out much faster.

 

Classic car owners are advised to use this information at their own risk.  I am not a fluid coupling engineer, a bearing engineer, or a lubrication engineer. I have done my best to find out what was in the original MOPAR Fluid Drive Fluid. This effort is in essence industrial archeology and should be carefully considered prior to use.

 

As a post scrip in 2014.  I ran across and old Gyrol book that talks about the filling of the fluid couplings.  In short, how much you fill it affects the torque-stall curve.  Chrysler set that by the position of the hole in the bell housing.  However, if one is to fill it a little less or a little more one can change the curve.  Do so at you own risk and never fill it past 90% so it has air in it to compress less you blow the thing up!.

 

James Douglas

San Francisco

[James_Douglas]

Fluid Drive

 

Fluid Drive was a $25.00 option available on the Doges, DeSotos and Chryslerss. Besides the cool looking Fluid Drive script on your rear deck, what did you get? Fluid Drive is a torque converter, that is, it converts engine torque and transfers it to the transmission via a fluid medium. The idea is simple. Imagine two electric fans facing each other. If you turn on one fan the air pressure created will cause the blades of the facing fan to spin. In this example, the fluid medium is air. The Dodge Fluid Drive works in a similar manner. The torque converter coupling is bolted to the flywheel. Inside the torque converter coupling are two "fans" facing each one another. The entire torque converter is filled with a special fluid. As the engine turns one set of fan blades (called vanes) is driven, forcing the fluid against the vanes of the facing unit. This causes that unit to turn which drives a standard clutch and pressure plate assembly. The power is then transmitted down the drivetrain to the rear wheels just like the standard drivetrain. The advantage of Fluid Drive is there is no direct mechanical connection between the engine and drive train. This translates into a very smooth power transfer and resulting smooth ride. It also provides some unique and interesting features. For example, to shift into gear you would put the clutch in just like a regular three speed. However if you are idling at a traffic light you can let the clutch out and the car won’t stall! That’s because at idle not enough energy is being transferred from the front vanes to the rear vanes. As you step on the gas the pressure increases and the rear vanes start to spin, transferring energy to the drive train. You would then shift gears like a normal three speed. You can also start in any gear. For example, you could start in third, even though the acceleration would be slow. In some ways, Fluid Drive is like a very simple automatic transmission. The units are essentially maintenance free. The only service requirement is to maintain the correct level of fluid in the torque converter coupling. A special access port is located on the passenger side floorboard on the side of the transmission hump. Remove the access door and bell housing cap. Turn the engine over until the filler bolt lines up. It is a good idea to stuff a rag around the opening so you can drop the filler bolt in the flywheel housing. The service manual recommends using a magnetic socket for the same reason. Be very careful as you fill the unit. Any spillage will always find its way to your clutch disk! After filling, make sure the filler bolt is secure with no leakage. The factory fluid was a Mopar #10 Fluid Drive fluid. Unfortunately this is no longer available. The original fluid was an ISO 32 (10W) with an anti-wear additive and an anti-foam additive which was needed to break up the foam which develops as the vanes turn in the torque converter (Fluid Drive Coupling). The non-foaming characteristics are critical because if air bubbles form the fluid will compress and power can not be transferred. Today, two replacement fluids are readily available. Automatic transmission fluid (ATF) is an ISO 32 fluid. However DEXRON ATF contains a seal swell additive which may swell old seals in Fluid Drives and cause a failure An alternative ATF fluid is Ford Type F fluid. It does not contain the seal swell additive. The best replacement is Universal Tractor Fluid #134. This is an ISO 32 fluid with all the properties of an automatic transmission fluid for wear, heat dissipation, and anti foam. Available at most NAPA stores in 1 and 5 gallon quantities. Obviously if you have a farm/tractor supply outlet nearby they will have it. Universal Tractor Fluid #134 has other positive characteristics including added shear strength for moving bevel cut gears under high loads similar to what is found in the old Fluid Drive transmissions. Many of today’s modern manual transmissions use the #134 fluid, not a gear lube, as the factory fill. The biggest repair problem with Fluid Drive is seal leakage where the transmission input shaft mates into the housing. Any leakage will quickly ruin the clutch disk. Repair kits are available but difficult to find. So are experienced repair personnel. Using the correct replacement fluid can go a long way in extending the service life of your unit. Otherwise the units are factory sealed. Carburetors used on Fluid Drive cars are different than the non-Fluid Drive models. The Fluid Drive adds some drag on the engine and a dashpot is used to slow throttle closing, thus preventing engine stalling. The adjustment of the dashpot and replacement of Fluid Drive seals are addressed in detail in the factory service manual. Lastly the same manual three speed transmission (Type C) is used on both Fluid and non-Fluid Drive applications with one part change. The Fluid Drive transmission has a slightly longer input shaft to accommodate the greater depth of the coupling. The shafts can easily be replaced making a standard 3 speed into a fluid drive version and vice versa.

Don,

 

The UTF #134 has hardly any anti-foaming agents in it compared to "circulating fluid". I have to respectfully disagree with you on your recommendation.  The thing that makes the oil relatively more or less expansive are the additives.  The DTE Mobil Circulating oil costs so much more than UTF #143 precisely due to the higher level of the additives to keep the stuff from foaming. A tractor by and large is using hydraulic cylinders which do not circulate in open cavities and as have no need for a lot of anti-foaming agents.  The fluid couplings do as they are only 80% full.

 

Hope all is well.

 

James

[Don Coatney]

James, The above is not my recommendation. I copied and pasted this information from the Resources section of this webpage. If it is not correct it will take a moderator to make corrections. You can report the inaccuracies and your suggestions by hitting the report this button at the bottom of the posting.

 

On the information you posted in response #6 of this thread you can post this yourself in the downloads section of this webpage without assistance from the webmaster.

[Dodgeb4ya]

Some pics of a 41 Dodge fluid drive coupling I just replaced the delicate graphite seal that was cracked.

 

Special tool set and other tools required to do the repairs.......

 

 

Note... No torque multiplication... "Torque converter" couplings were produced by Chrysler Corp starting in  1951.  A huge acceleration improvement!!!

 

Bob

Edited May 16, 2018 by Dodgeb4ya

[1950 Special Deluxe]

My car does not have a fluid drive.

However, I have found this thread very informative.

I now understand what they are and how they work.

Thanks for the info.

Neil

[greg g]

anybody want to have a go at Hudson Clutch Fluid???

[Dodgeb4ya]

I wish Fluid Drive Fluid was as easily available as the Hudson Clutch Fluid- it's all over Ebay and elsewhere for lubricating those odd cork clutches.

[casper50]

http://www.ebay.com/itm/VINTAGE-MOPAR-FLUID-DRIVE-BOTTLE-VERY-RARE-NOS-WINE-BOTTLE-STYLE-MAN-CAVE-ART-/171308518208?pt=Vintage_Car_Truck_Parts_Accessories&hash=item27e2c88b40&vxp=mtr

 

 

That's a little steep

[DJ194950]

Anyone heard of this seller??

 

DJ

[Tom Skinner]

Mix the ISO22 and ISO32 half and half

Right Sebolt or whatever - IT AIN'T ROCKET SCIENCE

[Plymouthy Adams]

I really am not sure mixing said components would be wise..some contents could actually react..or even worse coagulate and worsen any condition you are trying to prevent...

[greg g]

soon as I saw the price I knew who that was.  Our old friend from Farmingdale Mikey W and his buddy (ies).

[Dodgeb4ya]

If the fluid coupling is full of fluid -not leaking fluid on the ground and is working correctly don't mess with by doing a fluid change.

 

Don't drain it and spend 3 hours refilling it. It could end up leaking.

 

Bob

[dodgeguy]

Mr. Douglas, you sir are a Godsend! Thank you so much for your patience with me,a (newbie) and all your research  !  I am on the hunt for the right fluid now with a renewed since of confidence. And to all who beat me up over this subject being covered before I will wait till some one needs advice on a 39 chevy street rod which I do know a little about, but I will ! be kind.  LOL!

[Bingster]

Haven't I seen somewhere a firm who rebuilds fluid drive units?

[Markus1957M@aol.com]

Hey guys, I just bought a 1948 Dodge D-24 and I'm trying to get to the transmission dipstick. I pulled the cover off on the passenger side on the floor but there is a housing that has two tabs on it. What is the best way to get that off without breaking it? Thanks in advance and I'm sorry for the beginner question. She's very delicate and I wanna be careful. 

[Randy Brian]

where do you fill the thing up?

[busycoupe]

On the right side of the floor hump, just under the edge of the dash there is an access plate.  Remove this and you will see the round fluid drive unit.  With the engine off, turn the engine until you see the fill plug of the fluid drive unit in the center of the access hole.  Pack some rags around the plug so that when you remove it you don’t lose the plug into the bell housing.  After you remove the plug fill the unit until the fluid is up to the bottom edge of the threaded plug hole.   The position of the access panel ensures that you cannot over fill the unit. Replace the plug, remove your rags, replace the access panel and you are good to go.

[DonaldSmith]

Here's a photo.

 

The fluid coupling access is by that fluorescent shop light.  There's an oblong access panel in the floor and a round access plug in the bell housing.  The small plug is in the coupling itself. 

Have fun turning the coupling  just right.  (Underneath, there's a vent screen.  You can remove the screen to pry the flywheel by hand. You have to turn the coupling so that the plug is at the bottom, to completely drain the coupling. )  

(To the left is the access to the transmission electrial components.) 

 

[DonaldSmith]

Here's a trick for filling the coupling:  Small pipe nipple in the fill hole.  Larger 45 degree elbow, with reducing bushing.  Funnnel.