If the shaft torque applied exceeds the clutch friction holding torque,
which depends on the ATF friction coefficient,
how quickly do the clutch frictional surfaces wear to the point that they must be replaced in a rebuild?
Can it happen in one or a few dragstrip passes,
or one or a few maximum highway accelerations?
I ask because I once changed out ATF+3 to ATF+4 on a high mileage 46RH.
After the change out I did a few full throttle accelerations up a steep high hill.
Everything seemed OK,
but a few hundred miles later the TC clutches began slipping,
and a few hundred miles after that the overdrive unit clutches began slipping.
I later read in an SAE technical paper co-authored by Lubrizol Company and Chrysler
that ATF+4 has a lower clutch friction coefficient than ATF+3,
although ATF+4 has other numerous advantages.
Why did you change the fluid to start with?
The old ATF+3 was at the 30,000 mile interval.
Neither Torque Converter Clutch or Overdrive Clutch was slipping before the change,
but every now and then the trans was “bump shifting” while the truck was coming to a stop.
After the ATF+4 and a new filter went in,
the bump sifting was not felt anymore.
