[Audifan]

Originally Posted by Stromaluski

Nope. All things being equal, it makes zero difference in clamping force to have pistons on both sides rather than just one side.

Clamping force is purely a function of total piston area... on one side of the caliper. If you have two 50mm pistons on one side of a piston in a sliding caliper setup, it will provide the same clamping force as it would if there were two 50mm pistons on both sides of a fixed caliper setup. Yes, there's twice as many pistons, but that means that the pistons get half as much pressure, assuming the amount of force you put on the brake pedal doesn't change. Meaning that the resulting clamping force on the rotor doesn't change either because the twice as many pistons get cancelled by the half as much pressure. (There's obviously WAY more to it than that, but that's a pretty simplified way of thinking about it)

If you purely want your car to stop better, you'd actually be WAY better off buying better tires. Your car's limit in how quickly it can stop is purely a function of how much your tires can grip the road.

Using a more simplified example, here's something you can think about. If you can lock up the brakes on your car (assuming the car doesn't have ABS), then having even more clamping force will provide zero benefit at all. You can't make the wheels stop any more if they're already stopped. The same idea would apply even to a car with ABS. The limit of how fast you can slow down is an issue of how much grip your tires can withstand before they lock up on the road surface. Bigger brakes, more clamping force, etc won't change that at all.

Theoretically, moving the calipers outward (bigger rotors) will result in requiring less pedal pressure to provide the same amount of braking force on the road simply because moving the caliper outward provides a longer effective lever arm to act on the tire. But the bigger reason to move to different brakes is simply for other factors like increased fade resistance due to better cooling or more mass to the rotors. Or a more easily maintained setup. The sliding caliper setup is worlds easier to maintain and resist squeaks and resists seizing than a fixed caliper setup like the D2 Brembos. Not to mention, there's only like 3 companies that make brake pads for the D2 Brembos, whereas there's like 3 million companies that make brake pads for the D3 A8 brakes.

There's also handling changes to consider because adding weight to your brakes is un-sprung weight, which will negatively affect handling. However, if handling was that important... would you really be driving an Audi? Having the entire engine in front of the front axle is a terrible design for handling.

Basically a long post to simply say if you want to increase your braking capability... buy better tires.

Interesting.....