Hi guys, i have an arduino uno and just picked up a motor shield and an rc car. I have set up the rc car to drive forward and backward with the motor shield via serial and connected the steering to the motor shield also. My question is, can i control the motors at different times? everytime i try to control just A or just B, the steering and back wheels both move. I would like MOTORA to be the front steering motor (OUT 1 + OUT 2) and the back wheels to be MOTORB (OUT 3 + OUT 4). Ive tried powering the front motor by just using Analog pins but there isnt enough power. Can someone please help me out? thanks 
I went through their library file because it is odd but I am also prepping to control a cheap rc car chassis!
They do indeed have a way to directly control individual motors with the seeed shield!
motordriver.rotateWithID(MOTOR_CLOCKWISE, MOTORA);
so as i know you have already gathered that will send motor “A” clockwise.
motordriver.rotateWithID(MOTOR_ANTICLOCKWISE, MOTORA);
And that sends 'er the other direction. Personally im gonna use that in conjunction with the set speeds so i can tune my steering rate and momentum.
Hope this helps!
Here we go got the basics running on my platform now I just have to build my sensor array!
demo video on youtube for proof
watch?v=n7ig731nr2w
motordriver.rotateWithID(MOTOR_CLOCKWISE, MOTORA);
motordriver.rotateWithID(MOTOR_ANTICLOCKWISE, MOTORA);
motordriver.rotateWithID(MOTOR_CLOCKWISE, MOTORB);
motordriver.rotateWithID(MOTOR_ANTICLOCKWISE, MOTORB);
stop(MOTORA);
stop(MOTORB);
that will let you run each motor independently and in both directions.