Calibrate forward() via #define max_left till straight wheels
Calibrate pivotLeft() via #define pivotLeft_t, and power 0 to 100% till pivot is 360�‹
Calibrate pivotRight() via #define pivotRight_t till pivot is 360�‹
Calibrate turn(left_t or right_t, 90)via #define max_360 till 360�‹, check 90�‹

Note decelerate(100, 0); //as fast as possible
Note decelerate(100, 100); //from 100% to 0 for 100 millisecs