Backlash 37D Gear Motor with 19:1 Ratio

I’m debugging a balancing robot and having issues with the high backlash (approx. 3 degrees) with my banebots gearmotors (RS540 motors with 26:1 P60 gearbox). I measured the backlash with a digital inclinometer. I’ve built a balancing bot in the past with the Tamiya 72102 gearmotors with good success, but those parts are discontinued. I want to move on to a more sophisticated robot with motor encoders.

I’m interested in Pololu’s 37D gearmotors with the 19:1 gear ratio. I’d like to purchase 4 sets with encoders, but I need the backlash number. Has anyone measured it? Thank you.

Given that Pololu is the leader in motors and motor drivers in the maker/DIY community, I’m surprised that backlash figures are not available for the gearmotors in their inventory. But I suppose that is like publishing calories for deserts at a restaurant. I suspect backlash varies across several gearmotors. Can you state a range?

Hopefully Pololu can at least answer this… If a purchase the 37D gearmotors (19:1 ratio) anyway, measure backlash myself, and return them, is there a restocking fee?


Our motors do have backlash, but we do not have it characterized. We expect it to be a couple degrees. In this forum thread, one of our customers shares their experiences with backlash for those motors (he found it was about 1 degree).

Some of our customers have also made balancing robots using our 37D size motors. Here are some links to examples that you might find useful: … cing-robot … cing-robot

We only accept returns on unopened items, so you will not be able to return the motors you open to measure the backlash. If you open just one motor and it does not meet your requirements, you can still return the unopened ones, but please note, there is a restocking fee. For more details, please refer to the Ordering tab on our website.

- Grant