Victors not synchronized - dual motor train

[roknjohn]

Our bot uses the dual motor kit tranmissions (2 CIMs left, 2 CIMs right, and 4 884s). We noticed some rather loud motor noise (over and above the loud tranny noises) occasionally when accelerating. The sound is best described as a stalled CIM. We tried using Y-cables for the PWM signal to the two victors on each side. The noise still persists, though, like I said, is intermittent.

Funny thing though, if we wire both CIMs to one victor (yeah, I know its not legal) the problem is solved!

So, if the input signal in the same to each victor (via the Y-cable), how are we sure that the output is the same? Is there a way to calibrate two victors so that they behave the same with identical input signals?

John