Ha! The ongoing clutch saga....
Here’s my experience; I used to run a straight hydraulic ISO 32 oil in the primary cases of both the plunger (6 spring) and the SA (4 spring). This oil came out best after experimenting with different oils.
The plunger clutch always ran fine, but the SA clutch kept having a tendency to stick, so I changed both to ATF fluid.
This made no change to the plunger clutch, but it made the SA clutch slip and made no change to the sticking.
I changed the SA back to hydraulic oil, this stopped the slipping but it’s still sticky. When I clean the plates it behaves flawless but after an hour drive it starts sticking again. When pulling the lever the clutch takes a couple of seconds to release, and if I select first gear too hasty it replies with a crunch. Careful setup and an SRM pressure plate improved matters but only up to a point.
Strange thing is that it’s only the outer plates that are oily and stick. Further up the basket the plates are bone dry and release straight away.
What puzzles me most is that I have the plunger clutch running without the clutch cover, so oil can get everywhere but it never sticks, while the SA has the (in)famous oil flinger which seems to do it’s job in keeping oil away (except from the first plates). I did an experiment with a chain wheel of which I removed the “flinger” but this only made things worse so back to square one.
Investigations ongoing....