Originally Posted by MteK
BTW Gary, all this is said respectfully, it's just my understanding and not law by any measure.
I still stand by my opinion that from a performance stand point number of pistons is less important then rotor size and to your point, cooling.
Then again,I bought my Brembo GT's 98% based only on bling. But they do perform well and look good.
Oh, number of pistons was the point? Yes, that's true. Number of pistons doesn't matter. It's the total surface area of the pistons that matters, at least for braking force.
In the stock 135i calipers, having three small pistons instead of one or two big ones might actually be causing problems. We've seen evidence of some kind of uneven or incorrect piston pressure when the brakes are stressed, which the RacingBrakes guy said was a big cause of his rotors cracking in my car and FocusedIntention's car.