Good evening dodj! I don't purport to 'know' for sure but, my understanding is that the OC spring serves the purpose of pulling the clutch pedal back up *away* from the floor. The diaphragm I installed (McLeod) doesnkt have a problem coming off the floor so much as, simply not returning the l-a-s-t 1/2" to 1" into its full return up. In my case (as shelby dogg pointed out) that was enough to "rest" the fork on and cause the engagement of the throwout bearing, "all" the time.
Now, everyone (Mcleod, Centerforce, C-C members here) explained to me that I must remover the over center spring when I went diaphragm and C-P even explained to me how the diaphragm(s) will wind up over-centeredover center spring causes the clutch to stay "stuck" in the down position -- when shifting at high rpm's.
For me, the challenge was finding a suitable spring that would go into that "stock" location. And stay there.
A lot of what I let "wrap me around the axle" in figuring this out was that long-g-g neck (or straight shaft) on the tock OC spring. I assumed I had to find something similar (and I may still have to).
In my circumstance ANY spring in (or to a point, even if only "close" to) the stock location assisted in returning the clutch pedal to its fullmost "return" or "up" position.
Clear as mud?