Having trouble with cim motors

So let me just start by saying that we’re using spark motor controllers for the motors they are the motors are regular cim motors working with the drive train so the problem we are having is that one side is going faster then the other please help us

I hate to say this… but is your code fine? That’s the first thing I would check. After that, try calibrating the sparks.

User manual:
http://www.revrobotics.com/wp-content/uploads/2016/01/REV-11-1200-UM-00.pdf

It could be as simple as a loose connection meaning that one motor on a side isn’t receiving power, also depending on which gearboxes you are using one, could have been fitted with a slightly different gear ratio than the other?

Are the motors new or have you used them on a previous year’s robot?

Does the problem follow one motor regardless of motor controller? Or does the same motor controller always run the motor slower?

What about friction in the drivetrain? Does the slower side feel more difficult to turn by hand?