Combined thread: fluid drive repair and swap of semi-automatic to standard transmission

[Bobandy]

It was sort of sticky with an oil like glaze but it wasn't dripping oil or anything like that....  It only had a one and half gallons of fluid in the coupling.  I must admit that the oil pan and rear main seal were both leaking as well as the two valve cover gaskets...  I've replace the rear main oil seal & new oil pan and valve cover gaskets...  That may have contributed to the issue... especially the rear main oil seal... it had been replaced before and it wasn't very well done at all...  Although, it really didn't look like engine oil.  I think it's a slow leak at the coupling seal which probably only leaks when in use...    Now if I can find this Universal Tractor fluid #134.  Bobandy - Bob
 

[Dodgeb4ya]

Fill it with Hy tractor fluid-Better have plenty of time for filling it!!!!

Run it and see. Don't hang up the input shaft in the FD coupling--you can cause the seal to leak.

[James_Douglas]

Do not use tractor fluid or ATF or...  No, and no, and no.   Here I will post again for the god knows how many times...

 

**********

 

Technical Note on MOPAR Fluid Couplings
 (Fluid Torque Couplings are NOT covered by this Technical 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

[Dodgeb4ya]

Note well taken James.

I just re- did a 41 dodge FD coupling a couple months ago for a guy and forwarded your ISO 22 ect. tests from about a year or two ago to the customer who re -filled it.

He's very happy with it.

I personally do not ever change the fluid in these fluid couplings if they do not leak as I do not want them to leak.

 

ATF is an absolute NO NO.

I use 10W oil in the Fluid Torque Drive self contained couplings and works fine.

Edited September 21, 2014 by Dodgeb4ya

[James_Douglas]

Note well taken James.

I just re- did a 41 dodge FD coupling a couple months ago for a guy and forwarded your ISO 22 ect. tests from about a year or two ago to the customer who re -filled it.

He's very happy with it.

I personally do not ever change the fluid in these fluid couplings if they do not leak as I do not want them to leak.

 

ATF is an absolute NO NO.

I use 10W oil in the Fluid Torque Drive self contained couplings and works fine.

The one thing I would like to find out in a definitive way is the information on the decline of the additives over time and the effects.

 

Several of the engineers I have talked with on this subject all tell me that the anti-rust and anti-foam additives have a life of about 7 years.  On the shelf or in a fluid coupling.

 

It would take a lot more time and money than I want to spend to come up with hard numbers on the question.

 

I can say that from a seat of the pants feeling that when I went from regular ISO to the "Circulating ISO" fluid that the off the idle performance felt much better up to 10 MPH.  The anti-foaming agents I feel do make a difference in the fluid dynamics in the coupling.  Of course is it worth the 3 times the cost? 

 

In any case, I use it and have been happy with it in the Big Desoto.  It may well be in a smaller lighter car the difference would not even be noticed.

 

I do wish that the web master would take the entire tech note and post it in the repair section as opposed to snippets of it. Once you understand how the thing works, the issues of lubrication all start to make sense.  I have toyed with playing around with the stall speed by over or under filling the unit and see what it drives like.  One of these days when I have time I may well do it.

 

Best, James

[Dodgeb4ya]

I appreciate all the effort you have done to educate us in an important way on this FD coupling issue.

Thanks!

Bob

[Don Coatney]

James, You can post all that information in the tech section yourself. Does not require moderator intervention.

[Bobandy]

I think I know the answer... but far from sure...  I have the Gyromatic in my 52 dodge.  Been looking at options for installing  3 spd manual.  Is the input shaft from the semi-automatics identical to the input shaft for a factory installed 3 spd manual for a Fluid Drive setup.  I know that both use the the long bell housing.  I think the input shafts are the same length but suspect the diameter in the area of the 10 teeth that engage the clutch disc are different.  That is, the two input shafts are not identical.  The diameter of my input shaft at the 10 teeth is pretty close the 1 1/4 inches.   Am I right about this or totally confused???  Thanks, Bob (Bobandy)

[Bobandy]

I'm fairly new to this forum but I've been around cars and garages since a teen ager.  A couple of months ago, I acquired a 52 Dodge Coronet with a sick Gyromatic and wanted to replace it with a 3 spd manual while keeping the Fluid Drive Coupling.  I now have a transmission but it's a tad bit sick.  Bottomline, I need three gears.  1) Low Reverse Slider (853886),  2) Cluster Gear (no number), and 3) Reverse Idler..(no number).  The trans case numbers are:  embossed tag: 8-3,  main number:  1139152-10,  and there is a bold "H" below the main number...  Also, I believe the trans is from a 50 Dodge meadowbrook and it is definitely a fluid drive tranny with the long input shaft.

Looks like the problem was caused by a clash of gears from reverse to low before coming to a stop and without clutching...  Anyway,  I'm looking for help in locating a source for these gears...  Any help will be most welcome...

I'm sure a good parts book would be a lot of help but I don't have one..  Anybody have a recommendation for a good parts book??

Bob

[Plymouthy Adams]

did you not save your three speed behind the fluid coupler or is this the one you speak of?

[Bobandy]

Actually I'm replacing the original Gyromatic with a 3 spd manual.  They 3 spd manual is the one with the three bad gears (bearings are also shot)...  Just got the 3 spd about a week ago and found it to need a bit of fixing.  This I can do if I can find parts.   Any help is appreciated.  Bob

[Don Coatney]

Contact George Asche Jr. 1693 Fertigs Road Venus, Pa. 16364 814-354-2621 No web site

 

Just noticed there are now 5 threads discussing this same transmission issue. Perhaps a moderator can combine them so all answers can be found in the same location.

[DJ194950]

Bobandy, pics of the gears?

Sometime if teeth are Not missing they can be cleaned up with a slight grinding of the edge of the teeth if it's just some rolled and rough edges.

 

Info from an older standard transmission repair shop.

 

DJ

[William Davey]

Try Northwest Transmission in Winchester, Ohio.  

[plyroadking]

I don't know about new gears, i usually take a 1940 through 1956 standard transmission and swipe the gears out of it. If you cant find one i can probably dig up a set

[Mark D]

Not that there's always a great deal, but I've seen these gears on eBay lots lately.

[Bobandy]

OK.  I'm going to try to post some pics of the gears.  After reading some replys, it might be that only one of the three (for sure) needs replacing.  The cluster may be repairable with a steady hand.  The Reverse idler may be ok as is although not perfect...  But the Low Reverse Slider is for sure is not usable.  Bob
 

[Plymouthy Adams]

look like a bang box by the looks of things...ouch

[DJ194950]

OK.  I'm going to try to post some pics of the gears.  After reading some replys, it might be that only one of the three (for sure) needs replacing.  The cluster may be repairable with a steady hand.  The Reverse idler may be ok as is although not perfect...  But the Low Reverse Slider is for sure is not usable.  Bob

 

 

I agree with your assessment of the gears . A  slow gradual cleanup with a dremel tool first with a grinder bit on the worst then a very fine sanding wheel should work to the job-edges ONLY!  Did that to my my 3spd. main gear box w/OD and works good and No noise after 2K miles.

 

Watch Ebay and check on sources that will (have been) mentioned for the one really bad gear.

 

If unable to find one I can check my stored stash of tranny gears for you, but I'm sure I don't have a really nice one.

 

DJ

[_shel_ny]

...