Friction Modifiers in Automatic trans fluid?

[Emmett]

Speaking of apples and oranges, an IP and a clutch are two very different things.
I run JP-8 (jet A-1) in my multi-fuel and my ford. No doubt that Jet fuel needs a bit of help on the lubrication side, ATF seems to work well.
I could care less about a red tinge to the fuel as I have never been a "safe sally" and just can't be bothered with it.
How about some neat-oo youtube videos about how ATF works in a pump...?
An IP is not a friction device. It does not need to ingage clutches, it mearly increases pressure of a fluid and directs it somewhere that needs that pressure to operate correctly.

 

[ODdave]

Carl- I have pourd it from the same bottle. Its the same fluid. It is marketed for the rear axle but we use it in trans's as well. I learned the trick from my first boss ( He was an Ex gm enginer who helped on the gm diesels) And new his sh!t. Lerned things from him I would never belived unless I saw them, Then somtimes still had trouble.

 

[supermechanic]

Many pieces of heavy equipment specify 15w-40 motor oil for severe duty use in automatic transmissions, Allison and ZF are two that I use with this requirement.
Lubrication is specialized field,a lifetime can be spent studying and learning this science.
A chemical engineer is the person best suited to satisfy these questions, anybody know one?

 

[akonitony]

Dave - I don't believe the same modifier would be used in the two different fluids. So, saying the same modifier has two different effects in the two different fluids just isn't likely to be true. The only thing the same, if my understanding is correct (and that's always subject to question), about friction modifiers in ATF and limited slip diff fluid is the name 'friction modifier'. Not the same substance added to the oils at all - each has its own formulation.

I believe this page: AMSOIL Friction Modifier
will add credit to his statement, as it states "It is not for use in automatic transmissions or other applications requiring ATF." in the last sentence of the next-to-last paragraph. In the first page I linked to earlier, it gives several different molecular classes of compounds that are making up frictions modifiers. The best way to explain them, other than the Joe Dirt's pappa's way of "nobody knows - it just does!", there are different types that do different jobs. Some increase friction and some decrease it, and are in a class all their own known as dispersal agents.
I'm in agreement with the guy who says "why burn ATF unless you have to?" I figure I can use it if I need to get somewhere and all I have to drive is the deuce and all I have to power it is ATF, but until then, it's going to run on #2 diesel, or regular gas with 1 quart WMO mixed to every 15 gallons of gas.

 

[nf6x]

Purchasing an aftermarket limited slip differential oil additive and then pouring it into both a differential and an automatic transmission does nothing to imply that the additives normally found in over-the-counter gear oil and over-the-counter ATF are the same. I could pour salad dressing into both my differential and my transmission; whether it makes them work better or worse, it tells us absolutely nothing about the normal additives found in either fluid, and nothing about what effect either of those additive formulations might have on a fuel injection system.

 

[ODdave]

I am asking what it is / how it works if it has two completly different effects on fluids. I am not saying it makes it better or worse for you to burn.

Re-reading post's, I am asking about the additive, Not the original formula's of the two fluids.

 

[Carl_in_NH]

Fair enough, Dave.

As for the additive, I don't think it's possible for it to have two different effects in two different fluids (unless it's somehow reactive with compounds in the fluids themselves - but we should discount that argument here) - the bigger question is does it _really_ work and have two different effects, or is it just a great marketing department selling snakeoil? I suspect it's the latter, and it might not really help or harm too much in either application. Whether people believe it helps and pour it in is one thing, whether it really does what's advertised is another matter.

 

[greenjeepster]

Please see the article from Ford Motor co that I linked in my first post: It is specific to automatic Transmissions and states that Friction modifiers reduce friction. In the link that Akon linked is also specific to Automatic Transmissions and states that friction modifiers Reduce friction. His article goes on to name a second additive known as Dispersant which are added to Increase friction...

From the article I linked in post # 1.

A reduction in dynamic friction due to the addition of the friction modifier was clearly observed over the entire speed range. This indicates that the boundary lubrication mechanism is dominant under this condition, and therefore surface-active friction modifiers can effectively improve the frictional characteristics. The friction reduction was more pronounced at lower sliding speeds.

From Akon's article in post #6.

Most the anti-wear agents and the friction modifiers reduce friction coefficients at low sliding velocities. Dispersants (succinimide) and metallic detergents (phenate and sulfonate) can increase friction coefficients at high sliding velocities

Both of these articles are specific to Automatic transmissions and both state that the Friction Modifier Reduces friction.

It is quite simple: The molecules of the Friction Modifier bond with the working parts and put like a slimy coating on them....(think of the slime on a river rock, once you jump on it you slip off, but the next person who jumps on the same spot will get the traction of the rock now that the slime was removed by the fisrt person) this coating reduces friction when the working parts come together and prevent the jumping, clanging chattering and what ever else you get when a moving part engages with a part that is either stationary or moving slower..... But as the pressure increases (or heat depending on the application) The Modifier looses it's propensity for the metallic surface and is sheared off.... there by it is no longer reducing friction and the clutch can grab.

They are called a modifier because they reduce the friction of the original fluid under specific conditions.... where as if they just reduced it all the time the transmission would slip.

They do not increase friction under any circumstance. There are two types of friction modifiers, one looses it's reductive properties to pressure and the other to heat... Regardless of whether it is applied to a transmission, differential, or engine oil it is doing the same thing... reducing friction.

 

[greenjeepster]

I believe this page: AMSOIL Friction Modifier

What is the purpose of adding it to the differential? To Reduce noise and wear. What causes noise? Friction of the two moving parts trying to mesh up.... how do we reduce that noise? We make the surfaces more slippery temporarily so the parts slide easily together and that reduces wear on the parts.

The fact that this Friction modifier in your link above is not formulated for ATs does not change the fact that it is still doing the same thing that it does in a transmission. Just like w 30 motor oil is not formulated for the hybrid engine in a Toyota Prius. The 0w20 and HD30 are both motor oils and do the same thing in their specific applications, but they are not interchangeable.

As far as the cleaning properties of ATF go... it does have Detergents in it. I would also be interested to know it's Ph... Probably a little on the low side.

 

[Kohburn]

I'd be more worried about running synchromesh than ATF - even then not worried about synchromesh

 

[Carl_in_NH]

An interesting discussion.

If reduction in friction is indeed always the result, then it lends credence to the idea of a single substance being added to both a automatic transmission and a limited slip differential; this might make both types of clutches engage and disengage more smoothly. That said, there must be second order effects to this as well. For instance, is the holding power of an engaged wet clutch reduced at all from the modifiers permeating the lining material which is in contact with the metal friction surface and therefore allowing that friction reducing molecular bond to the metal surface to take place? I suspect it has a lot to do with surface roughness of the materials in contact and the spring pressure holding the surfaces in contact. If you’re expecting such an additive, you can take it into account when you design the various clutch types and overcome this possible limitation through proper application of lining material or spring pressure (or both). In an older vehicle, it might have unintended consequences (although they might not be all that serious, like having your limited slip differential clutch slip a little before it might otherwise).

What it tells me is more research is needed – at least on my part.

As for an IP not being a friction device, I beg to differ; all devices with sliding or running fits have friction associated with the movement of parts, although unlike our discussion of clutches, friction isn’t the intended point of its operation. What I was referring to is the thin-film performance of the material in question when the clearances are very small. Is the fuel (ATF) just as slippery when the clearances between parts are significantly smaller than one sees in a transmission? IP plunger clearances in its bore are miniscule compared to a shaft in a bushing. That said, the question remains as to whether or not it makes any difference. Saying that using some fluid as fuel has no ill effects we likely need to know something about the intended design operational life of the pump using the intended fuel, and what life you get when using the alternate fuel. Pulling a number out of the air, if the pump was intended to last 50,000 miles, and an alternate fuel caused it to fail 20% earlier, then it still wouldn’t fail until you’d run 40,000 miles. I think we need to look to users that have run the fuel in question for very long periods of time to get a better understanding – but then again, variability in the manufacture of the pumps being tested might cause one to fail earlier than another without being associated with the fuel itself.

 

[nf6x]

I think that the only way to get the real answer would be to run controlled tests in the same manner that engine oils, gasoline additives, etc. are tested (to the best of my knowledge): Start with multiple brand new engines that are as nearly identical as possible. Tear them down and carefully examine mating surfaces to determine their conditions, as well as making any other necessary measurements to characterize the starting condition of each engine. Then run them all under identical conditions, except for using the different oils or fuels. Afterwards, tear them down again and quantitatively examine the wear. In the case of gasoline additives, it's my understanding that they do things like measuring the mass of each valve before and after the test on a laboratory analytical balance to figure out how many nanograms of crud accumulated on the valve. These sorts of tests are well beyond the means and abilities of most of us collectors.

This is why it's hard to get real answers to questions like the one we're pondering here. It's expensive, time-consuming, and difficult to get the necessary rigorous data. All we generally have is semi-informed conjecture and anecdotal evidence.

 

[greenjeepster]

An interesting discussion.

If reduction in friction is indeed always the result, then it lends credence to the idea of a single substance being added to both a automatic transmission and a limited slip differential; this might make both types of clutches engage and disengage more smoothly.

Here is an article from Machinery Lubrication magazine that does a good job of explaining the physical properties of Friction Modifiers:

"What is a friction modifier? How do these modifiers help in industrial gear oil?"

Friction modifiers and mild anti-wear agents are polar molecules added to lubricants for the purpose of minimizing light surface contacts (sliding and rolling) that may occur in a given machine design. These are also called boundary lubrication additives.

Esters, natural and synthetic fatty acids as well as some solid materials such as graphite and molybdenum disulfide are used for these purposes. These molecules have a polar end (head) and an oil-soluble end (tail). Once placed into service, the polar end of the molecule finds a metal surface and attaches itself. If you could see the orientation of the molecules on the surface, it would appear something like the fibers of a carpet, with each molecule stacked vertically beside the others.

As long as the frictional contact is light, these molecules provide a cushioning effect when one of the coated surfaces connects with another coated surface. If the contact is heavy, then the molecules are brushed off, eliminating any potential benefit of the additive.

When the machine designer anticipates more than light surface contact (from shock loading, for instance), then the designer would select a stronger type of friction modifier characterized as an anti-wear additive. Zinc dialkyldithiophosphate (ZDDP) is a common anti-wear agent. This type of additive literally reacts with the metal surface when the reaction energy (temperature) is high enough. The reaction layer provides sacrificial surface protection.

As the loading and metallic contact increase, the strength of the additive and reaction process increases. This leads to the use of sulfur-phosphorus based extreme pressure (EP) chemicals. The EP additives form organo-metallic salts on the loaded surfaces that serve as sacrificial films to protect against aggressive surface damage.

There are two main types of EP additives, those that are temperature-dependent, and those that are not. The most common temperature-dependent types include boron, chlorine, phosphorus and sulfur. They are activated by reacting with the metal surface when the temperatures are elevated due to the extreme pressure. The chemical reaction between the additive and metal surface is driven by the heat produced from friction.

Much like when you rub your hands together, as the metal surfaces come in contact with one another, there is heat generated by means of friction and pressure. In reacting with the metal surface, these additive types form new compounds such as iron chlorides, iron phosphides and iron sulfides (dependent upon which compound is used). The metal salts produce a chemical (soap-like) film that acts as a barrier to reduce friction, wear and metal scoring, and eliminate the possibility of welding.

It would be interesting to be able to get actual reports from people running straight ATF in their trucks on actual hrs and if they have had to rebuild any IPs.

 

[akonitony]

Just a side not, and I do agree with Carl in his last post, but to be clear, the friction disks are not held in contact against the steels by springs in and automatic transmission, they are separated by piston return springs (yes, there really is such a thing, but it is not found in an engine). They are held against the steels with hydraulic pressure.

 

[73m819]

CAN anybody tell us what is in atf as a FRICTION ENHANCER

 

[FireFighterHill]

The only experience I have with a friction modifier is in my mustang. The rear diff requires it or the tru-trac can pop while turning at low speed. Before you can understand how friction modifiers function, it is important to understand how "wet" clutches perform.

In a wet clutch arrangement, there are three stages of engagement. During the first stage, the clutch is not in contact with the pressure plate or other metal plate. We will use an automatic transmission torque converter as an example. Anyone who has driven auto trans cars with lockup torque converters for a while has probably experienced a phenomenon known as "lockup shudder" or "torque converter shudder". Shudder is caused during torque converter clutch lockup by burnt fluid or fluid wich has exhausted all of it's friction modifers. The result is a chattering feeling when the torque converter goes into lockup mode. I will now attempt to explain the physics of wet clutch engagement.

As I have already mentioned, during the first stage the clutch is not in contact with it's mating surface. The fluid itself, however, is acting as a viscous coupling, causing a partial engagement. A side effect of this is heat, and I believe you all know that heat is the killer of automotive oils.

The second stage is very simlar to the first. At this point the clutch is very close, possible within thousandths of an inch, from it's mating surface. The viscous coupling is now more effective, but the pressure and shear load on the fluid are also higher, and the result is increased heat.

During the third stage, the clutch actually contacts it's mating surface and positive engagement is reached. The shear load of the fluid has been overcome and has either extruded itself outside of the clutch material or, depending on the application, has partly or entirely extruded itself through a porous friction material, thus exiting the engagement area of the clutch.

Now that we have an understanging of wet clutch engagement, lets see how that plays out in the real world. If a fluid has lost a substantial amount of the friction modifier, the shear of the fluid will be inconsistant accross the engagement surface and the clutch will briefly alternate between full engagement (stage 3) and viscous engagement (stage 2). The as power through the assembly varies, wich is connected in our case to a vehicle that we are inside of, a bucking of sorts is perceptable to it's occupants as power transmitted to the wheels is momentarely interrupted and regained.

In an application like a limited slip rear end, similar phenomena occur but in a slightly different manner. Because the clutch plates are constantly loaded with heavy springs, in theory they should always remain in stage 3 of lockup. If that were the case however, they would never slip. So the purpose of a friction modifier in a rear end is to ensure that the transition from S3 to S2 and back again during cornering etc. is smoothe. Therefor chatter occurs in much the same way it does in our torque converter clutch scenerio.

So the answer to your question if friction modifiers enhance friction or reduce it? The answer is there is no answer. Depending on what the application calls for and how it is engineered, they can do either. So as Alex said, it does just that; modifies friction.

 

[nf6x]

That sounds oddly familiar...

 

[FireFighterHill]

Well I got it from bobistheoilguy.com didnt feel like typing it all out in my own words so I searched till I found a post that explained it how it has been explained to me.

 

[nf6x]

You could have saved yourself some trouble by cut-n-pasting it from earlier in this very thread.

 

[akonitony]

You could have saved yourself some trouble by cut-n-pasting it from earlier in this very thread.

Yep - post #6 to be exact.