Why is increasing you braking efficency by say 25% (as advertised my a cross drilled rotor package) that benificial when the ABS engages with the stock system. By making the brakes work better doesnt that just make the ABS activate sooner and more often. they way I understand it, the ABS engages to make you stop in the shortest distance posible so if you feel the pedle vibrate, you gonna stop quick.<p>I know I'm missing something.....

Brake modualtion is one big key. The better the modulation, the closer you'll be able to get to the threshhold of where the tire is almost locked up but not. This allows you to not simply jam the brakes on until ABS engages. ABS is not the quickest and best way to stop in a perfect world. The best and quickest is to be just at the point where ABS is about to engage. This is above most of us drivers though. Another big bonus is the more efficient your brakes, the less fade. This means that under repeated braking you should see quite a difference. The racing forum has had some good discussions on fade.

Better efficiency translates into more braking force, which means that your brakes will be able to do more work, or in other words, stop you in shorter distances.<p>It's just like making your engine more efficient. You can do things to add power, but if you do things to increase efficiency, you get the side effect of more power.<p>So, by inceasing the braking efficiency, you increase your braking power. The ABS does not come into play all the time. It only activates when you really slam the brakes hard.<p>I've been autocrossing this year and I can tell you that I am limited more by the brakes in the car than the total power output. On the courses that I've driven, I could not afford to use all of my engine's power to accelerate up to a turn, because I found out that my brakes could not slow me down in time to make the turn without hitting a cone or going off course. I found that I had to back off of the throttle sooner than I'd like, because the A4 brakes weren't strong enough to slow me down for the kind of driving I was doing. Does that make sense?<p>Last weekend I rode with a Corvette driver on an oval track with cones on it. He was screaming into the turns and then doing hard braking. It was better than an amusement park! Anyway, he rode with me and gave me pointers on how to drive the course. It was my worst run of the day by a long shot, and the reason is because my brakes did not perform anywhere near the way his did. He told me to accelerate up to the turns, and then he expected my brakes to be able to slow me down for the next set of cones. It didn't happen. My brakes could not slow down my car like his vette did. I learned that I couldn't use his techniques because I can't count on my brakes like he can.<p>Drew S.<br>

The gent that owns the performance shop that I go to has a 4 year old Camry V6. He's done quite a bit to it and one of the things was a brake upgrade. He has cross-drilled rotors with BIG AP callipers. Boy, do they make a big difference. Despite that fact that the car has ABS, he's able to brake much harder than stock without the ABS engaging. Also, like Gary mentioned, the brakes don't fade as fast under repeated braking.<p>One side effect is that cross-drilled brakes tend to become very squeaky when they heat up.<p>Just as a note, in Formula 1, they use carbon-carbon brakes (discs and pads are made from carbon compounds) and obviously no ABS. In one issue of Autosport, they mentioned that in this years Williams Car, Heinz-Harold Frentzen achieved 5.99 g under braking!<p>Marcin R.<br>---<br>'98.5 A4 1.8Tqms

ABS does not stop you in the shortest distance possible. ABS is to prevent loss of control in a hard braking situation.<p>To stop in the shortest distance, the most effective way is to lock up the wheeels (friction). When the wheels are locked, you have no control over the car. ABS attempts to prevent this by not locking up the wheels.

I would bet that you couldn't lock your wheels at 100MPH with factory brakes (not that I'd want to), but that means you have not achieved maximum braking ability at those speeds. Why? The brakes are not strong enough to overcome the force of friction generated by a locked tire sliding on the pavement, but I bet you could easily do this at 50MPH. Now if you increased your braking power, you might be able to lock your brakes at 100MPH because they'd be able to overcome the force of friction. Thus even with ABS you would be reaching maximum braking power faster, thus slowing you down faster.<p>Ever notice that in Road and Track, for example, they test braking 80-0 and 60-0. Sometimes you see cars that are separated by about 10 feet in stopping distances at 60-0. Taking into account solely the difference in speed, stopping distances on those two cars should increase by about 18 feet at 80-0 [(80^2)/(60^2)*10], but the result is more like 30 feet--this is because one car has better brakes than the other--ones that grab harder and fade less during braking.<p>I had a Celica once that I pretty much hauled ass in everywhere I went. It suffered from brake fade pretty bad; I could notice it just around town; if I had to come to fast stops several times in a row (I even had a half my master cylinder go out once while braking almost full pedal--luckily I did not have to make that turn and could keep going straight--that added about 50% to my stopping distance) the pedal was soggy and the car was slow to stop. This is much harder to feel in the A4, but I've been able to detect it still. I'd love to upgrade my brakes, but I guess I'll save my pennies and wait for an S4.

There's an excellent article written by Patrick Bedard in the 11/98 issue of Car & Driver on brakes. <br>As the others have mentioned, brakes are as important as power, suspensions and tires are to any performance oriented driver.<br>If all you plan to do is run back and forth to work and such, there's probably no need for you to upgrade to better brakes.<br>If you ever plan to get in to track events such as the driving schools offered by the Quattro Club or any autoX, you will immediately begin to see how your brakes fade and get spongy under high speed, repeated braking.<br>As the others have mentioned, on the track, you can go faster and deeper into corners, repeatedly with better brakes. <br>When I first began doing events, I didn't push the car hard enough to really notice the limits of the brakes....now, I lose the stock brakes within the first few minutes on the track. (As money permits....the brakes will be upgraded.) On the street, however, they have been more than adequate. So it really depends on your needs. <br>Read that C&D article, I think you'll enjoy it.<br>-Cathleen<br>

To stop in the shortest distance you want to be just on the threshold of lock-up. Once you lock your wheels at high speed your tires will begin to overheat to the point that your are sliding on a thin film of liquified rubber (you'll notice the smoke and nice burning rubber smell). In which case, the friction between the tires and the road is so low that you would be better off without any brakes at all.<p>The purpose of a big brake system is to not only provide greater stopping power, but also to be given much more control over the use of that power.<p>kosta

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The main point of ABS isn't to stop the car more quickly, but instead to allow the driver to maintain steering ability while the braking interval has not completed.<p>Cameron<br>