Why doesn't BBK = faster stopping time?
 

I keep reading threads on how BBK will not stop the car any faster, but I think that's just a misconception. Look at my example. Suppose your car comes with 225 mm wide tires and you decide to upgrade to 245 mm. There will be an increased contact patch (assuming same brand of tires), and you will have more grip.

Same thing with brakes. Since you have a larger rotor, with larger pads, the contact patch between the rotor and the pad will increase, allowing you to stop quicker.

This is a part of an article that appeared in grassroots motorsports magazine:
[QUOTE]We installed the larger NX2000 brakes onto our SE-R this Sunday, after we retested the braking distances. The average distance of ten stops was 161 ft. While we had the VC2000 hooked up, we also retested the 0-60 time, coming in with an average of 7.6 seconds, about .6 faster than we basedlined the car at.

The brake install was very straightforward, we only needed to trim a little bit of material off of the backing plates for the larger NX2000 caliper brackets to clear. After the brakes were bedded in (using the same type of Carbotech Bobcat pads) and allowed to sit overnight, we retested the 60-0 braking distances. They were shorter by about 5 feet.

Looking at the numbers a little closer, it

Your only contact with the road is through the tires. BBKs don't increase tire grip. If you can lock up your tires (exceed their traction capability) with your current brakes, then a BBK won't reduce the ideal minimum stopping distance.

In the example above, the stock brakes "faded" after repeated hard use(overheated, and could no longer exceed the tires' traction capability), whereas the BBK didn't. That's the advantage. However, for many cars, most if not all of that advantage can be gotten with just a change of pads and fluid, while leaving the rotors and calipers alone.

:iagree:

Why would larger bracks stop anything quicker? There is more then enough brake on the car as it sits. If they are lock the wheels, they have done their job. the OEM can, so can the BBK.

You quoted this "This highlights that big brakes don

That makes sense. I understand more now.

Im surprised you are confused when the explanation is in the Grassroots article you brought up. Reading comprehension can do wonders.

There is a little bit of complication involved when you start considering the way the Cf of the brakes depends on the speed of the car (it's not actually linear). An OEM brake system that can lock up the tires at 80 mph may not be able to lock up the tires at 150. The BBK mostly adds more heat capacity, but it can also add some actual braking force capability at very high energy conditions. Sometimes.

If you can engage ABS with the stock brakes, or lock the tires up with non ABS stock brakes, what good will more stopping power be to you when the tires have already exceeded their limits?

Let's say you have an car w/1000hp that accelerates from 0 to 100 in 9 seconds with it's rear tires right at the limit of adhesion the entire time. Would another 10, 100 or 1000 horsepower get you to 100mph any sooner? Well the NOS sales guy might claim that it will....

Face it--most guys buy BBKs for looks and justify their auto-accessorizing addiction with increased performance claims. Like 90% of all go-fast goodies, the only place anyone could quantify the benefits of brakes/aero/carbon fiber hood props is on the track. And since most credit-card swipin squids are too busy incessantly preparing for the track instead of driving to an event, it doesn't really matter what something does.

With that said, I run a SBK. 30lb less mass than stock w/ducting instead of mass to keep things cool. Brakes are just as potent at the end of a session as they are at the beginning--even with rotor temps over 900 deg.

also you have to look at the brake bias, many times by adding a bigger front brake in the front you change the stock brake bias and now the the rear does zero or little work, meaning the fronts have to do more now off setting the big brakes.

when these cars are designed, that take a lot of that consideration

uh, brake bias doesn't affect stopping distances either.