Twindisc TMC40M - what tranny oil?

[Mirage35]

Does anyone have a definitive answer? I have a Twindisc TMC40M transmission and don't know what type of oil it needs. The operating manual doesn't specify, and the diagrams helpfully show a little icon labelled "OIL" next to the drain plug and another labelled "ATF" next to the fill plug.

I have e-mails in to the dealer and the manufacturer, but neither is very responsive.

[txg]

ATF is the answer, easy to get at many places like gas stations and car repair shops. ATF means automatic transmission fluid.

[Mirage35]

Yes, I know that's what ATF stands for, but their manual is so ambiguous that I'm still worried. And I found another generic manual that seems to cover all of their transmissions which says that some use automatic transmission fluid and some use engine oil (without, of course, specifying which models).

When I have access to the boat (another 6 or 8 weeks, depending on when it warms up here) I'll pull the dipstick and maybe drain a little bit to see if I can tell what it is.

Thanks.

[Mirage35]

To show why the manual is confusing me - here's the diagram. It appears that I put ATF in the top and drain OIL out the bottom?

[Simi 60]

A few posts down

TMC40 gearbox oil

Ain't Google grand

[kmacdonald]

I think it can use either. It's a mechanical gear so is not too particular. The hydraulic gears need ATF.

[Mirage35]

Originally Posted by Simi 60

A few posts down

TMC40 gearbox oil

Ain't Google grand

Thanks, I had found a couple of threads on that site, but not that one. And there are different versions of the TMC40 so I was happy to see that it referenced specifically the "M".

[Mirage35]

Originally Posted by kmacdonald

I think it can use either. It's a mechanical gear so is not too particular. The hydraulic gears need ATF.

That helps to make sense of what I saw in the generic manual.

[a64pilot]

ATF and motor oil have vastly different coefficients of friction.
That probably isn’t the correct word, but slipperiness sound silly.
Even with ATF there is a significant difference, back from building automatic transmission in the 70’s Ford ATF had significantly less slipperiness than GM’s so you used Ford ATF when you put in a shift kit to make the clutches and bands slip less.


In my opinion the chart clearly states ATF, ATF is frequently called oil.

ATF is a very high detergent very light oil, with red dye of course, it’s usually the detergent property that clutches want to keep them clean.

It should be easy to verify what is in there with a paper towel and your nose, but that doesn’t mean what it in there is correct.

[Mirage35]

Originally Posted by a64pilot

...
It should be easy to verify what is in there with a paper towel and your nose, but that doesn’t mean what it in there is correct.

I suspect that what's in it is what came with the installation. It's 8 or 10 years old but the engine only has 100 hours on it so that's probably not as bad as it sounds.

[kmacdonald]

From a google search: https://www.granvilleoil.com/news?artID=9

[a64pilot]

Well, that is hypoid hear oil, a completely different animal of course, it’s what is in your outboard lower unit etc.

[a64pilot]

Originally Posted by AnglaisInHull

I suspect that what's in it is what came with the installation. It's 8 or 10 years old but the engine only has 100 hours on it so that's probably not as bad as it sounds.

If it’s tranny fluid, it should of course be thin as water almost, and red, hard to mistake for motor oil.
If it’s hypoid gear oil, it will stink like a rotten egg from the sulphur in the oil.

[oleman]

Our old paragon hydraulic gear driven by a Detroit 71 uses sae 30 non-detergent oil. So all hydraulics do not use ATF.

[Offshore1960]

I have twin disc gears in my tugboat and we use Chevon URSA 40 super plus. Have not had any issues with them at all.