those are 390x26 mm rotors in the front and 365x26mm in the rear

what is this sliding caliper they are talkin about but it looks crazy though

 

I saw some of those up close on an E63 AMG with black calipers. It looked hot! Those are some serious brakes.

 

Wow... what a caliper. Maybe one day we'll see a caliper that wraps the whole rotor

 

Yeah I have 4 of those on my airplain. The calipers that wrap the entire rotor. all three rotor per tire

 

actually u know Mercs have the best brakes

look at the audi s4 and the Bmw M3, they only have a huge single piston caliper which i think such a rip off for the price u pay for the cars

but the C55 AMG comes with 13.6 inches with nice 4 piston calpiers

 

the number of pistons is like the size of the wing. Untile your doing like 180mph, its all for show. If audi and BMW can manage to get the same clamping force out of one piston, then for power to them.

 

no stopping 60-0 is mostly tires

the more piston the more responsive the brake system will be

 

I hate to break it to both of you, but the number of pistons has nothing to do with braking power at any speed. It's snake oil, a sales pitch. Braking power comes from friction against the rotor from the pad (which has nothing to do with piston count) and the effective ratio between the master cylinder and the slave cylinders (not dependant on the piston count). The reason that multi piston brakes seem to work more effectively is that many small pistons are generally spread out over a larger pad surface area, which in effect means that the rotor doesn't care how many pistons are pushing it, it's just that the friction is increased by larger pads. In reality, one large piston with the same volume pressing on one pad with the same area will brake identically as the same volume and area being pushed by many smaller pistons.

The reason that many small pistons are used is simply a packaging issue. First, one large pison takes up a lot of room in one place, making it hard (especially if you have large diameter rotors) to fit inside the wheel. Many small pistons can be arranged in a more space efficient pattern. Secondly, they can help prevent the pad backing from warping due to heat, since the pressure is applied more evenly across the pad material. While these are both very beneficial things, they have nothing to do with braking power, which seems to be what you two are bickering about.

In the end, if the volume of the slave cylinders and the area of the pads are the same (with all other variables being equal as well), the brakes will have the same power, doesn't matter if they have one piston or 18 million. The ONLY way to increase braking power is to increase friction between the rotor and the pad by either increasing pad area or using a different pad material, or to change the ration of the master/slave cylinders. The overall power of the brake is all in the friction coefficient between the rotor and the pad. The responsiveness of the brake (if by responsiveness we are referring to the differing input required to recieve the same output), is all in the ratio between the cylinders added to the friction coefficient.


With that all being said, increasing brake power today is largely uneffective. As was (mostly correctly) stated, the biggest variable in braking in modern cars is the tires. Every car made today can get the ABS system working at almost any time. Since this is the case, take two identical cars, with the same weight, same aeros, and most importantly, the same tires. Now one of them has a basic brake system, junky pads, one piston, regular fluid, and the other has the most high tech carbon rotor 8 piston system that you can fit to it. If the car with the junk brakes will lock up the tires and initiate the ABS system, then the car with the F1 brakes absolutely WILL NOT stop soner than the first car with the ABS working. either brake system, no matter how basic or advanced, can only slow the car as well as traction will allow. If the first car's brakes are capable of generating -1 G and the second car's brakes can do -3 G, if the tire is the same between them and can only handle -1 G, then both cars will decelerate at -1 G, regardless of the brake's extra power. Feel will be different, but the actual performance will be identical.

The benefit of greater braking power is very real though. By over building the brakes, even if the car doesn't stop faster because if traction issues, you are still helping because the over-build brakes will be working further away from their limit, meaning that the work is less likely to over-load the greater braking system. This equates to less fade, less natural wear on the consumable items, and greater bling factor (I suppose).

Thus ends today's lesson.

 

I was gonna say that but into the first sentence I rememberd that I can't spell, Kinda gave up after that.

 

i was gonna say when u have more pistons u have more surface covered but i was to lazy to put it in