Consider 2 cars. An S4 and an A4. For the sake of argument assume they both weigh
the same and are both fitted with identical tires.

Why is it possible to stop faster w/ the S4 because of larger brakes when the tires would
seem like they would be the weak link in the whole equation? If you brake hard enough to
acitvate the ABS on both cars wouldn't that would mean you would be stopping at the maximum
amount the tires have to offer. Why does the S4 stop faster?

I understand the brakes are converting the enery of the moving car into heat thereby
slowing it. There must be some physics involved that I'm not privy to.

"If you brake hard enough to acitvate the ABS on both cars wouldn't that would mean you would be stopping at the maximum amount the tires have to offer. Why does the S4 stop faster?"

Assume for the moment that both cars use the same ABS system (you can actually stop faster without ABS if you know what you're doing). The S4, with bigger brakes (i.e. higher net braking torque), will be able to engage the ABS system sooner (at a higher speed) than the A4.

It will also be able to dissipate heat better, helping it stop quicker from higher speeds. Too much heat is a bad thing for brakes (so can too little).

In your proposed scenario, I doubt you'll measure much difference in a cold stop from 20mph. At a 100+mph the ball game is completely different.

Dwayne
94 S4

Impending lock up is the point at which the disc is about to lock. At this point, you get maximum braking. ABS works because it can keep the brake at impending lock up. Now a larger disc is alot more stable than a smaller disc. Therefore, it can get closer to impending lock up without actually locking up, even on ABS cars. Therefore more braking can be applied, henc the car stops quicker. Now with cheap tires, this is even more evident, as they are easier to lock up, or induce ABS. The stability of the larger disc allows it once again to get closer to locking than a smaller disc.

Heat dissipation also plays a role in consecutive braking.

Ned

in softer sprung cars it takes longer and since you are travelling at speed, distance goes by quickly, increasing stopping distances. So even fractions of seconds matter. (hypothisis by SWAG method)