Fluid Coupling Rebuilding

[James_Douglas]

I wanted to let everyone know that I have received emails from Northwest Transmission parts in which they state they they are rebuilding Fluid Couplings.

 

Now, for the record, I used them to "rebuild one" in the mid-2000's. What I got back was a unit that got a new set of bushings and a new seal. They did not replace the bearing or open it up. About three or four years later (@2500 miles a year) it failed and started to leak real bad. I stuck in a spare as a temporary measure and it has worked fine for over 10 years.

 

They are telling me that they are now cutting open the units, replacing the roller bearing, the bushings and machining the Turbine to accept a modern seal in place of the carbon seal. I asked if the seal could be replaced, with the transmission out, but with the coupling in place just like the factory seals. (Assuming you have the tools). The answer was yes.

 

The price is $1200

 

Best, James.

[Doug&Deb]

Thanks for the information. I’ll keep it tucked away in case I need that service.

[Adam H P15 D30]

A modern seal opens up the choices of fluid you can fill it with. 

[MarcDeSoto]

Do you recommend something called TDH fluid as a replacement for FD fluid?  It's a hydraulic fluid made for tractors.  Is it the same as the Mobil 1 hydraulic fluid?

[James_Douglas]

I sent an email to NW transmission and asked for specifics on the seal material. When ones knows that, then one can say what fluid should or should not be used.

 

If it is one of the series of Viton Series of fluoroelastomers then it is likely that the Mobile Circulating fluid would be fine with it. But, I would check with the seal manufacturer for confirmation.

 

Two things to remember. One is that the fluid needs to be THIN just above what the roller bearing needs for lubrication. The second is that it needs a LOT of anti-foaming agent in it. If the oil foams, it will slow the velocity and the power transfer.   Almost all regular hydraulic oils, nor ATF, have enough anti-foaming agents. That is why I picked Mobile DTE Circulating fluid. It is also why every 7 years or so it needs to be replaced. The anti-foaming agents have a useful life of about 7 years. Even in the can.

 

James.

[MarcDeSoto]

James, I am planning to buy the  Mobil-5-gal-circulating-oil-pail-32-iso-viscosity-10-sae-104743.  

 

I just read 48 New Yorker's post about changing the FD oil and that is what he highly recommended over the other Mobil product I was going to buy.  He tried them both, but found that the above product Mobil part #104743 gave much better take off from a stop and better performance than the other oil.  

Edited December 26, 2020 by MarcDeSoto

[James_Douglas]

Marc, I am using 104743 ISO32 NOT SAE10. An SAE 10 oil is thinner than ISO 32. If one had a good bearing it in theory would perform better all other things being equal.

 

The BIG issue is that unless one knows the EXACT amounts of anti foaming agent in each oil, then a head to head comparison is worthless.

 

Remember, it is the velocity of the oil in the coupling that transmits the torque. Not the viscosity. Any aeration will lower the torque transmittal. So, unless one knew the levels of anti foaming agents in each oil, it is near impossible to do any comparison at the margins. Also, was a "standard day used" a difference in air temperature of 10 degrees will change the torque output of the engine and on and on.

 

For me the big deal is the state of that bearing in the units. I would use ISO 32 (SAE15) oil in my cars and not anything thinner.

 

Also, these things get very hot. Hotter than people think. The VI of the oils are also important.

 

James

 

 

[MarcDeSoto]

Mobil Light Circulating oil is SAE 10, as well as ISO 32.  That's what the spec says:

 

https://www.grainger.com/product/MOBIL-Mineral-Circulating-Oil-4ZF36

[Sniper]

In another thread I posted the specs on the various ISO grades, it also listed the approximate SAE viscosity,   ISO 32 is SAE 10, if you want another SAE then the ISO grade will not be 32.

 

[James_Douglas]

A chart like the following: http://www.golftechs.us/Reference/viscross.pdf

 

Is what I have on the subject. There is an actual formula to convert ISO to SAE.  The ISO to SAE numbers are not exact unless you use the formula.  I think that SAE15 is closer to ISO32 than SAE10. If someone wants to run down the formula and do the math, be my guest.

 

All I know is that when I talked with the engineer at Gyrol, he told me to use ISO32 with a lot of anti-foaming agent in it and change it every 7 years. Since they held the Patent on the design and licensed it to Chrysler, that is good enough for me.

 

James

[Loren]

Now this brings up an idea.

In every industrial area I've lived in there are Industrial Oil suppliers who will custom blend whatever formula you need.

Apparently there isn't much magic to it. Locally (Carson City, NV) there is an Industrial Oil supplier who was only too happy to duplicate the Mobil DTE series for my needs.

If you want 10wt with anti-foam additives I am certain anyone of them would be happy to supply your needs or specifications.

They might even be able to analyze a sample and come up with suggestions all with a price competitive product.

If James can get the specs from his contact at Gyrol, it's a done deal.