[Dean]

Originally Posted by BAN SUVS

I have yet to lock up my brakes at the track... and I'm still considering running r-compounds.

This is one of the common misconceptions. Getting into ABS is not necessarily fast, and in fact is often fairly slow. Being fast is about balancing forces in a smooth fashion. But that is a whole different discussion. Getting into ABS also does not mean your brakes are operating at their maximum performance, it actually means they have failed.


Warning: Dean's Soapbox mode enabled. Preaching begins in the next paragraph. You have been warned.

And actually, brake selection is lagely about modulation, or the systems ability to create high levels of friction without locking up. I know that sounds contridictory, but it isn't. This is where heat capacity, cooling and pad compound come in. I'll try and explain with a exagerated example.

When a rotor is extrmely hot, it actually deflects under the pressure of the pads. This is bad! So at the leading edge of the pad, a slightly thicker rotor is continiously being compressed. As I understand, this area of interferance is where lockup actually begins, and where if you do not release the lockup the pads can actually fuse/weld themselves to the rotor. If instead, the system as a whole, but mostly the rotor stays cooler and therefore deflects less, minimizing this interferance area, you will see an increase in braking performance. This area is also why in most any fixed caliper multi piston per side configuration, the leading piston will be smaller, allowing the leading edge pressure to be lower than the mid to trailing edge.

Thsi is why I keep emphesising that the diamter of your rotor is not very important, but the width and cooling fins are! Even thermal mass doesn't do you any good if you can't cool it.

Look at the many NASCAR series... As far as I know, they are all running under a 12" rotor.(11.75"x1.25" I believe is most common). Do any of us really think we in our weekend warrior roles can hold a candle to the demands they put on their brakes? Other series run even smaller diameter brakes. If bigger was better, don't you think some series somewhere would run them?

Braking is not about stopping the rotor, it is about stopping the car which whether you believe it or not is done by the tires! Dispating energy without locking up is how you do that. getting into ABS means your brake system has failed, not that it is running at maximum performance. I'm not saying ABS is bad, only that is not a valid measuring point.


Soapbox mode disabled.

I am far from an expert on this, and would love to hear other technical opinions on this becasue there is certianly more I can learn on the subject. I just feel obligated to speak up when I see/hear these types of automotive myths being discussed.