*Why*, Does ABS make That Sputter in the Pedal.?

I was reading off of howstuffworks.com, and regarding the abs system. It said that while applying the brakes, with abs, you will feel a violent sputter/vibration in the brake pedal-when a heavy braking is applied.

I tried this today, on a dead street-in the rain nontheless, and i did feel the vibration in the pedal. No skidding though :-)

These braking techniques are under extreme situations, not normal braking-only when you gotta really stomp the brake.

The ABS motor is in between your foot and the wheels. When the sensors kick the ABS on, the motor modulates the pressure and since its between your foot and the wheel, you feel the pulses back on your foot just like the pulses the wheel gets.

Exactly.

the abs motor is just used to pressurize the hydraulic system. the pulsing you feel is the action of the electric solenoid valves opening and closing.

the abs pulsates like that to prevent skidding it senses a wheel locked up and pulsates the brakes on and of for better steering control. If this is happening prematurely chances are you have a wheel speed sensor dropping off!