Wild Thumper Controller Left/Right speed way off


i'm using a Wild Thumper controller on a DFRobot 4wd chassis and motors.
I noticed if I set a certain speed, there's a lot of difference between the left and right wheels.

But it is not consistent. The speed tends to equal out after a few seconds.

And it is dependent on the direction. e.g.: going forward starts with left going faster than right, and with going backwards it starts with right going faster than left... weird....

 The effect is worse with higher speeds...

Any ideas?


yah. i was just adding the
yah. i was just adding the encoders, even they weren’t compatible with these motors and chassis (not enough room), but they work… However since the motors Start with the biggest difference, it has turned already before i can even make a useful encoder measurement… But i guess i just want to know: is this difference normal? could it be because i’m using 5 NiMH AA’s? I do see quite a voltage drop running at higher speeds…

All motors are not built the same.

Encoders should allow you to assist in keeping the motors all moving near the commanded speed.

I think I should expand on my subject line. As all motors are not built the same they will move at differing speeds in different directions.