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#530806 - 04/01/04 09:25 PM ATF
MolaKule Offline


Registered: 06/05/02
Posts: 14485
Loc: Midwest
Name the five (5) major functions of an Automatic Transmission Fluid!

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#530807 - 04/01/04 09:52 PM Re: ATF
novadude Offline


Registered: 01/16/03
Posts: 1348
Loc: mechanicsburg, PA
1. Lubricate
2. Cool
3. Hydraulic clutch application
4. power transmission (TQ converter)
5. provide proper levels of friction to ensure proper clutch engagement

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#530808 - 04/02/04 12:45 AM Re: ATF
T-Keith Offline


Registered: 01/20/04
Posts: 4865
Loc: MN
Use for hydraulic purposes.
Lubrication for gears.
Cooling and heat trasnfer.
Transmiting power in TC.
Friction modification for clutch.

Basically the same as above. [I dont know]

-T

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#530809 - 04/02/04 01:28 AM Re: ATF
Asinine Offline


Registered: 02/22/04
Posts: 127
Loc: Eastern Seaboard
Over breakfast cereal
Over pancakes
Salad dressing
ATF Sundae with nuts
Slip N' Slide lubricant

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#530810 - 04/02/04 09:36 PM Re: ATF
MolaKule Offline


Registered: 06/05/02
Posts: 14485
Loc: Midwest
T-Keith and Novadude had the correct answers.

ATF's are hydraulic fluids that have to cool, transmit torque, provide hydraulic pressure for actuators, reduce wear, keep the tranny clean through dispersants and low levels of detergents, and lastly, provide the proper dynamic friction for the friction surfaces.

See also this thread:

http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=4;t=000315

And of course, Asinines answer certainly reflected his Handle.

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#530811 - 02/21/05 01:19 AM Re: ATF
MolaKule Offline


Registered: 06/05/02
Posts: 14485
Loc: Midwest
For automatic transmission fluids, the Level of Specification, whether it be a DexronIII(H), a Mercon variety, Toyota T-IV, Honda ATF-Z1, or whathaveyou, DOES NOT specifiy the base oils.

The fluid developer must come up witha fluid that meets the specification for oxidation resistance, friction modification retention, etc.

Ususally, an additive company like Afton (formerly Ethyl) or Lubrizol, or Infineum, or XYZ, comes up with an add pack for that specification. They then suggest a base oil mix for that formulation.

The formulation gets tested, and if it passes, everything is hunky dory. Usually, it doesn't pass the first time and has to be tweaked for various reasons, such as for example, friction modification retention.

After testing, the additive supplier is confident the additive package can meet the specification requirements for various base fluids.

As the specification heat is turned up, higher Group fluids must be used, such as Group III minimum, in order to pass certain tests.

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#530812 - 02/22/05 07:55 AM Re: ATF
Blue T Offline


Registered: 04/01/04
Posts: 44
Loc: South Florida
Of the 5 ATF functions listed above, which are the most critical for the proper performance of a given ATF in a given transmission? I assume any ATF will do all 5 to some degree but which ones are critical to the point that they will cause problems? I ask the question because I have a car with a transmission (ZF 5HP19) that requires one specific fluid which is expensive and difficult to obtain and probably voids the warrantee if you don't use it. It would be nice to have a substitute fluid but how can you have any assurance that the substitute will work properly without actually trying it - something I would be reluctant to do, even after the warrantee period, given the high price of the transmissions. The specified fluid is a "lifetime fill" fluid but I'm one who would prefer to do shorter change intervals.

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#530813 - 02/23/05 04:31 AM Re: ATF
MolaKule Offline


Registered: 06/05/02
Posts: 14485
Loc: Midwest
Novadudes 1 nad 5 are the most important.

The fluid must first have the correct lubricant viscosity and Viscosity index to operate over the temps of operation.

Proper friction modification is needed to insure the proper static and dynamic friction coefficients for the bands and clutches.

A third would be the proper amount and type of Anti-Wear additives.

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#530814 - 02/25/05 08:13 AM Re: ATF
Steve S Offline


Registered: 01/20/03
Posts: 18449
Loc: East of IGO
off topic but how many trans failures are from incorrect fluids compared to poor engineering or quality of the components.

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#530815 - 02/24/05 11:11 PM Re: ATF
kenw Offline


Registered: 10/10/04
Posts: 1979
Loc: Houston
quote:
Originally posted by Steve S:
off topic but how many trans failures are from incorrect fluids compared to poor engineering or quality of the components.

my educated guess is < 0.173%....Chrysler being <0.00132%....

[Wink]

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#530816 - 02/27/05 09:31 PM Re: ATF
brianl703 Offline


Registered: 05/07/04
Posts: 10487
Loc: Manassas, VA
quote:
Originally posted by Steve S:
off topic but how many trans failures are from incorrect fluids compared to poor engineering or quality of the components.

I've heard that incorrect fluid use is one reason that manufacturers are removing the dipstick from automatic transmissions.

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#530817 - 02/27/05 09:44 PM Re: ATF
MolaKule Offline


Registered: 06/05/02
Posts: 14485
Loc: Midwest
I think poor enginering/materials is the main reason transmissions have failed.

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#530818 - 02/28/05 05:36 AM Re: ATF
Mickey_M Offline


Registered: 08/13/04
Posts: 1001
Loc: Baltimore
quote:
Steve S:
off topic but how many trans failures are from incorrect fluids compared to poor engineering or quality of the components.

The explosion in ATF specifications is itself poor engineering.

Fortunately the oil companies themselves are bringing order out of chaos by devising formulas with high quality basestocks that work well across a variety of applications.


-

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#530819 - 03/01/05 03:40 AM Re: ATF
MolaKule Offline


Registered: 06/05/02
Posts: 14485
Loc: Midwest
Good Point, Mickey,

It is difficult to determine if the myriad of disparate specifications is due to differences in clutch/pressure plate materials, or whether it is a ploy to make sure the dealers get the first cut at fluid profits before the ATF compounds are reverse engineered. Maybe it's both.

I do know, from reading recent SAE papers and trade rags, that cellulose friction materials are slowly giving way to carbon composite and ceramic materials. Undoubtedly, these new materials have different Dynamic Coefficients of Friction.

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#530820 - 03/03/05 05:27 AM Re: ATF
rob-the-oil-nut Offline


Registered: 02/04/03
Posts: 529
Loc: Manitoba, Canada
Hi y'all!
Pardon me, MolaKule, this may be somewhat off-topic, but I was taught the 4 duties of an OIL (so, how much I am off-topic, I don't know) were to clean, cool, lubricate, and seal. Only TWO of these duties are part of an ATF's mission??
THANKS!
Rob

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