Hi All
Some People do not seem to realise that there are different 6 spring clutches on the rigid / plunger and the later swing arm models , so when owners of the swing arm models decry the later 6 spring clutch, owners of the earlier models jump to the defense of their clutches 
Also take note that BNR and Suzuki derived clutches are also six spring 
John
I will have to take that up with a certain physics professor ( ret ? ).
From an engineering point of view the 6 spring wet clutch is garbage particularly when the truth of the whole assembly is dependent upon the thick back plate sitting square against the center controlled by 6 ( from memory ) tiny 1/4" wide tabs thus any wear to the back plate or hub in this area gets amplified by the radius of the drum.
And despite being argued own I do know because we etched pressure plates to check, when you get a pair of spring holes and the center hole all aligned along the grain line these plates do flex.
Now considering that the total lift is quite small, it does not take much flexing of the pressure plate to cause the clutch to drag.
This random alignment happens because the plates were manually pressed from pre cut blanks , a very bad practice.
It is even worse on the 4 spring pressure plates where you get prefferencial necking across the rolling direction
The take away from this is if you have a pressure plate that you can never seem to make lift true, toss it and get another.
You can not get the same thing happening with odd number springs and if you look at the Burman clutches of the day you will notice they are 5 or 7 spring.
Even now days most clutches I have come across have odd spring numbers as do many flywheels
