Hydraulic Throw Out Bearing

[cobrashoch]

CUL8ER/ Kimba- The questions you ask can fill a tech manual.
Some basics though:
A diaphram pressure plates clamping force is pretty well maxed out at about 2800 lbs by design. Centerforce adds weights to the construction of their pressure plates that add weight and clamping force by centrifical action. It's been my overall experience with diaphram pressure plates that none of them will hold on engines that have more that 500 lbs of torque or if you use big tires, and that includes a Centerforce. A diaphram pressure plate can/will also STICK TO THE FLOORBOARD if you go past its internally set spring center line. Not to worry though if you are using a hyd. T.O. bearing as they don't have that much travel and cannot get past the pressure plate centerline. If you once stick a diaphram clutch to the floorboard it will come back weaker, and each successive time you stick it it will get weaker still because you are streatching the springs. Rock solid square contact patch with the disk is a good characteristic of this design.

Borg and Beck, long style, 3 finger, etc all :
By design more room for larger springs results in higher pressure plate holding pressures possible, but not necessarly so. Heavier construction possible also results in a pressure plate that takes heat better(less fade). Heavier components also means a heavier in weight clutch. This means, contrary to popular belief, that you can't shift a 3 finger clutch as fast as can with a diaphram clutch.
Going past the spring centerline when shifting, using this design results in a bent finger. This will cause clutch chatter when going down the road. Contact patch with the disc is controled by points with this design, as apposed a diapram above. In addition the housing has to be larger and tends to flex more. Bottom line is sometimes a 3 finger clutch will wear out the disc faster. I believe that all of these problems are addressed using the so called "pro" clutch settup. But that's another thread due to it's complexity.
A informal rule in drag racing with a 3000 lbs car is, you will need about 300 lbs of clamping force on your clutch for every inch of rear tire width. Design your clutch with that in mind and the chances are you can't go wrong. More later if you wish.
cobrashock