I just received two new XL motors direct from LEGO. The first thing I noticed, without any gear reduction, was that they sound different and run at slightly different speeds. Some questions came to mind that I'd like to present here in hopes of getting some answers from those of you experienced with these products:

Is it common for motors to be this different?

If the speed is different, could the performance differ as well?

What is a good way to measure the performance of these motors? (or any electric motor, for that matter)

Regards ~ Perry

Edited August 27, 201113 yr by PerryMakes

This is a good read for anyone interested in Lego motors (including the PF variants):

http://www.philohome.com/motors/motorcomp.htm

This is a good read for anyone interested in Lego motors (including the PF variants):

http://www.philohome.com/motors/motorcomp.htm

On the page you linked, there was a link to a page that answered some questions I had dealing with speed variation between motors.

You can easily test the differences with this:

Just plug both motors to the same battery box.

Yes, some motors sometimes work on different speeds however the difference shouldn't be serious. I have personally experienced two identical Lego City trains ran by the same, brand new batteries and one was going slightly faster. You can easily test it by creating a "conveyor belt" with a marker on it. Set a timer for ex. 30 seconds and count how many times the marker passes a fixed point you establish. If the difference is less than one rotation then I suppose it is negligible. If it is more than one then you can ask for a refund or warranty change.