I see this term used in various ATF fluid descriptions. What does "High Friction Modified" mean?
What does "High Friction Modified" mean?
- Thread starter Winston
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Lots of friction reducers added to reduce shudder.
It would be something like Mercon V or Chrysler's ATF+4.
It would be something like Mercon V or Chrysler's ATF+4.
OK, friction "modified" means friction reducers. I would think you could have too much friction reducer. Right?
I dunno. A lot of these "highly friction modified" ATFs are marketed as being acceptable for older transmissions. Ford says that Mercon V can be used in any Mercon application.
No, that's not it at all. All ATFs except the old type F used in older Fords have some friction modification. "Friction modifiction" means the frictions characteristics of the fluid are specifically engineered for the type clutch material used and to allow that material to "slip" under some conditions and to "grab" under others. These "conditions" are usually measured in speed and torque.
The most highly friction modified flud currently sold is Chrysler's ATF+3 and ATF+4. Mercon, Mercon V, and Dexron III all have about the same amount of friction modification characteristics, but not as much as Chrysler's fluids.
MolaKule
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Sure did, asbestos was a primary friction material for both auto transmissions and brakes until about the '70's.
Pennzoil does.
http://www.pennzoil.com/TechData/pdsheet/DomesticMarketing/Gear&Transmission/pdf/MerconV.pdf
Don't know about the part about Chrysler transmissions though.
So does Mobil:
http://www.mobil.com/USA-English/Lubes/PDS/NAUSENPVLMOMobil_Mercon_V_Synthetic_Blend_ATF.asp
And Castrol USA:
http://www.castrol.com/castrol/productdetailmin.do?categoryId=82915490&contentId=6003974
Chevron too:
http://www.chevron.com/products/prodserv/nafl/auto/content/atf.shtm
Plus Kendall:
http://www.kendallmotoroil.com/NR/rdonlyres/024D939C-17C9-4AD5-AFAA-C6848E99614D/0/K_MerconV_ATF.pdf
And Motorcraft (they're Ford, right?
http://www.motorcraft.com/products.do?item=15
Shudder reduction comes from using the correct friction modification for the type clutch material as well as the method of clutch engagement/disengagement. A "blanket" reduction in friction may reduce shudder, but it will also probably cause other problems, like fluid overheating and premature clutch wear. The key to eliminating shudder is a delicate ballance of just the right amount of friction, not the elimination of friction, per se.
OK. However - many of the newer fluids designed for lower shudder have been deemed acceptable for older applications. I can't imagine that the transmissions are designed for an **exact** frictional characteristic, as the available fluids will change over time (i.e. Dexron-II phased out in the 90's).
There really are no newer fluids that were designed with "new" friction modification characteristics to reduce shudder. The way the newer fluids (like ATF+4 and Mercon V) "reduce" shudder is by ensuring that the correct friction mod characteristics of the fluid don't deteriorate over time. Fluid related shudder problems stem from two sources: Using the wrong fluid, and when the friction characteristics of the correct fluid are no longer within spec. Fluids like ATF+4 and Mercon V were designed to address the latter by ensuring that the friction characteristics of the fluid would last the duration of "fill for life." In other words, shudder can be caused by fluid that is "worn out" and these new fluids don't wear out as fast.
Not true. Ford generally does not recommed backfitting Mercon V where Mercon was originally specified.
MolaKule
Staff member
Just to add to G-MAN II's comments, one also has to take into consideration the "type" of friction modification wrt "Highly friction Modified." In terms of formulating, this means more than say simply adding 120 mL instead of 92 mL.
It means providing the right amount (which we call 'dosage' here on BITOG) of a "specific" type of friction modifier. So when designing ATF's, these considerations apply:
1. Selection of proper viscosity for cold weather, hot weather application/driveability
2. correct anti-oxidants for base fluid type,
3. correct base fluid type for thermal and oxidation stability
4. proper amount (volume or %weight/weight) and type of friction modification for clutch type.
5. correct type and molecular weight of viscosity index improver,
6. correct type and molecular weight of dispersant
7. a small amount of detergent,
8. proper amount and type of anti-wear additives,
9. proper amount and type of anti-foamants
10. proper amount and type of metal deactivators
11. proper amount and type of rust inhibitors.
For more info, see this discussion and related links:
http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=4;t=000315#000000
It means providing the right amount (which we call 'dosage' here on BITOG) of a "specific" type of friction modifier. So when designing ATF's, these considerations apply:
1. Selection of proper viscosity for cold weather, hot weather application/driveability
2. correct anti-oxidants for base fluid type,
3. correct base fluid type for thermal and oxidation stability
4. proper amount (volume or %weight/weight) and type of friction modification for clutch type.
5. correct type and molecular weight of viscosity index improver,
6. correct type and molecular weight of dispersant
7. a small amount of detergent,
8. proper amount and type of anti-wear additives,
9. proper amount and type of anti-foamants
10. proper amount and type of metal deactivators
11. proper amount and type of rust inhibitors.
For more info, see this discussion and related links:
http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=4;t=000315#000000
But right now the tendency is for friction reduction to reduce shudder.
BTW - didn't older transmissions contain asbestos in certain parts to increase friction where you wanted it?
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