why does the over center spring have to be removed

just seems that every one I have talked to is saying that the OC spring most definitely should be removed when diaphragm type clutch is put in. its really hard to describe how this pedal is working with the spring in. seems like it engages it just about up to its top most position, and disengages about half way to the floor, when you push it down to the floor its easy half way down, then gets harder to put it to the floor, that's why I am wondering if all this is due to the OC spring being in there