[gramicci101]

Originally Posted by Fizz

Hmmm somehow I think the extra piston does not mean double the piston area as such....something to do with total clamping force being similar even though your got more piston)

I was told the below when I asked a similar question:

Originally Posted by gramicci101

I would have thought a 4 opposed piston caliper would have a fair amount more clamping force than a 2 piston sliding caliper.

Originally Posted by Dave-ROR

Piston area and line pressure determine that. The OEM calipers actually produce more torque per given line pressure than the WRX 4 pot fixed calipers, unless they changed the piston sizes. I honestly never measure the OEM ones but that was true with the WRX a few years ago.

Originally Posted by wheelhaus

That's a common misconception, but you have to measure the surface area of pistons on only one side. It has to do with how pressure is applied and measured. Look at it this way... With a four piston caliper, each piston is matched by it's opposing piston, so the fluid pressure of the system is the same on each side, it is matched and equalized, not added. With a one-sided caliper, the piston(s) push against a bracket, which has to push back with equal force.

From this thread.