Changing the oil of the Fluid Drive

[Uncle-Pekka]

Gents,

As I may have mentioned in the forum earlier,

I bought my first forties car, a '48 D24, earlier this year.

The car has been poorly "restored" in mid-80's and driven by several owners since.

As a summer treat, I though changing the oil in the Fluid Drive.

(Just for safety, I do not know what type or grade there is in currently)

Which way I am supposed to drain the oil from the Fluid Drive unit?

(I found the window to filler plug under the carpet, but where's the drain?)

[greg g]

It't the same plug. If you remove the dust cover from the bottom of the bellhousing, you can access the plug, remove it, and drain the unit. The rotate it up to the fill position and put the fluid in. In its proper positon it will fill to the proper level. Several people have reported good luck using Universal tractor hydraulic fluid. This is available here at Farm and tractor supply stores. It is the fluid used for hydraulic systems that operate lift buckets, back hoes, and other similar implements. If you don't have farm stores then commercial construction equipment places should also have it. I believe it comes in 5 gallon containers here. I believe someone mentioned using a garden hand pump pressure sprayer to ease the filling process. I believe it should be SEA 10 on the viscosity scale and should contain a low foaming additive.

[JIPJOBXX]

Napa stocks it and its what I used when I installed my rebuilt fluid drive. Cost around 10 to 15 dollars a Gallon. I think mine held about a gallon or so. Jon

[48mirage]

I am getting ready to do this myself. Can't remember where I've read it, and I have probably been exposed to too much information. But here is what I have read. The universal tractor fluid is a satisfacotory oil, I've also read the type "F" automatic transmission fluid is a satisfactory oil. The goal being finding the oil with the highest viscosity index, which is not the same as viscosity. From what I understand the Viscosity Index is a measure of the fluid's ability to transfer power. I have checked and find the type "F" fluid has the higher index of the oils I have looked up and I plan on replacing the oil in my fluid drive with the type "F" later this month unless someone can scare me off.

[JIPJOBXX]

It would be interesting to see what the difference in power would be from one oil to the other. As far as I can tell mine works just fine! Kind of slow but that's to be expected with that fluid drive outfit.

[PatS....]

You also need to be sure it's a non-detergent oil for the fluid coupling.

[Uncle-Pekka]

Thank You Folks!

Now I am ready for the job. I actually had the seller of the car to kindly buy me a five gallon bucket of the NAPA Tractor Fluid, which I belive is the #134 F-type stuff recommended at P15-D24 tips. The missing piece of information was the way to drain the unit, which Gregg G kindly told us -Thanks!

Pat - I trust the Tractor fluid would be non-detergent? Is that required because the unit seals won't stand detergent oil?

[PatS....]

I believe it is because of foaming...not wanted in the fluid coupling. The tractor fluid is recommended by many FD guru's...one of which I am not.

[James_Douglas]

The Viscosity Index (VI) is the measure of how a fluid holds its published viscosity over a particular heat range.

The higher the VI the more temperature it can be exposed to and maintain its viscosity. As heat goes up the viscosity of an oil tends to go down.

In organic oils, most of what we use in our fluid couplings, the manufacturer adds a chemical supplement to raise and stabilize the fluids VI.

After much research, I found out that those chemicals break down after about 5 to 7 years of life. Even if standing on a shelf.

So, unless you are using some kind of synthetic fluid that has a high VI in and of itself. I would recommend that all fluid drive cars drain and re-fill their couplings every 5 years.

If you do not, then you are in fact tossing out power.

Best, James

[Lou Earle]

I drained my 48 Dodge and put in napa tractor hydraulic fluid and is mad a significant difference in take off and non slippage.

I would ( and I did ) drain the unit overnight at the least if not a complete 24 hours. Then add the tractor hydraulic fluid. Follow the instruct ins in the manual

Lou

[PatS....]

I should drain and fill mine while it's OUT

[Uncle-Pekka]

Eh... just one more thing, Sirs!

I crawled under the car today and found out, that the dust cover of the FD & clutch will not come off just by removing the bolts to hold it. The rear end is held above a cross bar of the frame and the front end is in a deep valley behind the oil pan. Will the cover slide forward and off if I remove the oil pan? (It gets a bit tricky here...)

P.S.

Pat - You got it neatly exposed for the job! Congratulations for having such neat and tidy transmission - Great job, what you've done!

[Fireball]

What will happen with dexron III, slippage ?

[Lou Earle]

What will happen with dexron III, slippage ?

I do not know what will happen but I am curious - Why would we need to know Since we do know from the experience of probably 10 people the hydraulic tractor fluid works just great with no slippage ? Why take a chance?

[PatS....]

Interesting older discussion on AACA forum re DexronIII in the Fluid Coupling.

http://forums.aaca.org/showflat.php?Cat=0&Board=UBB62&Number=156500&Searchpage=1&Main=156180&Words=+Jon+Robinson&topic=&Search=true#Post156500

[Fireball]

I do not know what will happen but I am curious - Why would we need to know Since we do know from the experience of probably 10 people the hydraulic tractor fluid works just great with no slippage ? Why take a chance?

I'm just curious as well, why wouldn't something that is ment to be used with converters, Dexron III that is, work with fluid drive. The other forum had info that it works just fine, and from here I have learned that tractor fluid is good.

I'm not taking that chance, I will use the tractor fluid, it's even cheaper I assume. So I'm just wondering if it works or not.

Pretty much the same with engine oils. Synthetics are todays tech, and still I'm not using it with old U.S flathead. But I'm interested of the tech behind, why it is not the best solution for us, even when it's "the best" available in market.