I'll try. If you look at this picture and imagine all of the plates were in place you'll see that the pressure of the springs will be between the pressure plate (green) and the lip at the bottom of the drum (yellow). If a friction plate (H) was put in first at the bottom of the stack then the spring pressure would be between the pressure plate and the basket (pink) pushing the gearbox shaft, and hence it's bearings, outwards. It will also be pushing the bearing the basket turns on inwards.
Thanks Derek, great explanation. It's the clutch spring pressure applying a different load, which makes sense. What I couldn't understand was how the load from the engine drive could be any different, which it seems it isn't. Thanks again!
