Answered: Changin something on robot?

What if we were to change a gear on the robots drive train that would change the speed of the drive train? Would this be a legal action in autonomous, drive control, or neither?

This action would be done by sliding or taking off the gear, and placing a different gear in the drive train. Also by tightening and loosening collars.

Let’s take a look at the applicable rule from the VEX Gateway Manual. I’ve bolded the portion which is specifically relevant to your question.

Changing a gear on the robot would be considered changing the configuration of the robot and would not be allowed. Note, the quoted rule is only for the Autonomous mode, however the action you described would not be allowed during Driver Control mode either.