Drivetrains are not moving at the same speed (VexGO)

Evening all.

We are (our school) are new to VexGo.
We are having some issues with one drivetrain being significantly slower than the other. Other than swapping drivetrains what other trouble shooting is possible for us to resolve this issue. We know it won’t help us tomorrow during our competition, but we want to get better as the school year ends.

Thanks for any advice.


  1. If you’re using a built-in program, it’s probably either
    * your gearing
    * your motors
    * your brain, or
    * your battery
  2. If you’re using blocks, take a screenshot and share it here.
  3. If you’re using text, put ``` and paste all your code.

Nobody can help you if they don’t know your code, build, gearing, wheels… In short, anything about your robot. Somebody once said, “It’s like coming to the forum and saying, ‘Is this apple red or green?’” Nobody can see the apple; nobody can help you.


Hello there. Do you mind sending a picture of both robots (particularly their drive) and of the code on both robots?

Sorry, per the rules new users can only put one embedded media item in a post.
This is the robot we built.

There was no coding done by the team.
We used the drive mode on the Vexcode-Go application.

Right now our first Vex Go competition is over, but I want us to achieve more next competition in late March - early April.

Thanks for any help you can offer.

1 Like

I would test things in this order:
From VEXcode GO, create a program with a drivetrain configured.
Use two blocks - set drivetrain velocity to 100% and then drive forward for 500mm.
Run this program on both Brains. Do they drive at different speeds?

If so, swap the Brains between the robots and repeat.

Still different? Is the same drivetrain slower? Swap the left drive motors between the robots and test again.

Finally swap the right drive motors between robots and test again.

This process should help you identify which component is causing the difference.


Alright, looking at how close the wheels are together, and how close the wheels are to the base, it looks like it may be causing friction from the wheels dragging on the base. Or the other wheel, I’m cant tell if they are actually touching or not but it does appear that the wheels are touching the base, try spacing them out just a little more to make sure the wheel is only contacting the shaft or spacers and not any other part of the robot.
Also, is your other robot drive built the same? Try swapping only the motors on both drives, if the other motors work fine it could be a motor problem although that probably isnt the case.
Also check to make sure your brain and controllers firmware is up to date (I’m not familiar with vex go’s system but V5 brains have frequent firmware updates and sometimes out of date firmware will cause issues with motors as our team has experience with our robot in the past.)
Also on the back of your robot, below the brain I noticed what looks like a battery that is riding really low to the ground, it seems like it clears the ground but check to make sure. (If it’s not touching the ground than it’s fine)