Oopps, Title should have been Tetrix Motor now has plastic gear.
Has anybody had trouble with the gear boxes from the new Tetrix motors? After grinding a few we took one apart and found that one of the gears is plastic. We have had some old ones apart in the past and they were originally brass. Is Lego saving that much money going to plastic? I am willing to pay a couple of dollars more to get the brass ones. I wonder if Lego will warranty the motors? If I take the old brass gears and replace the plastic ones will that be legal?
The other gears aren’t necessarily metal, either. I seem to remember a composite gear or two somewhere in there as well. Search the forums for ‘Tetrix motor’ and look for posts from the FRC 2011 season. There’s a plethora of gripes about them and how quickly things break down under stress.
Yep, plastic. And the motor shaft is made out of a softer material so set screws now bite in and loosen when subjected to reversing loads. Unimpressive for an “improved” version. This was the Tetrix tweet about the motor:
"It’s official!!! New and improved DC motor released. More power, tougher gear box, increased burnout protection. "
My team made the mistake of upgrading our motors at the start of this season. We still have a stock of used old ones and we are swapping out as needed. Unfortunately it is not FTC legal, but an old gearbox on a new motor might be a good combination.
In light of Tony Allen’s post about which motors were affected, I took a more thorough second look. The “plastic” in our failed version 2 motor was a blob of white grease. When I disassembled the gear box the gears were in fact all metal. My apologies for the incorrect information.
And, before I give out more incorrect information, I’ll put the output shaft on a hardness tester to get some non-anecdotal data.
