Re: Ultramatic ATF

Posted by Redhexagon On 2023/9/24 2:25:31

FA is basically just F that is upgraded for longer service life. Its friction properties are the same as F.


I have an old car magazine from the 1960's sitting in my library somewhere that has an article talking all about the characteristics of the different types of transmission fluids and how the transmissions were designed to work on each of them. It's been a long time since I read it. I wish I could find it right now.

Basically, from what I can remember, Dexron produces a smooth slide into engagement, so the valve body is calibrated to apply the clutch quickly and let the fluid do all the work of smoothing things out. Meanwhile, Type F tends to slip a lot at first then suddenly grab, so the valve body is calibrated to apply the clutch much more gradually. I do not remember it saying anything about the old Type A fluids.

Those differences between Dexron and Type F were only during dynamic friction situations where the clutch is slipping during a shift. I think it said that the static or holding friction properties are the same between them, which means Type F will do nothing to stop your direct drive clutch from slipping under load.