pic: Toughbox Gear, destroyed

[MrForbes]

I've worked on cars for years....the gears used in automotive transmissions and differentials are made of very very hard steel, and will last for a very long time with proper lubrication. Without lubrication, they will be destroyed in a matter of miles (I've done it myself by forgetting to add oil to a differential on a car I built).

Use grease! add a little more grease if you aren't sure exactly how much you need.

[gauntletguy]

However you do not want to add so much grease that it goes onto the shafts as our team had learned the hard way. A mentor told some of our students to grease the gears but they greased all of it and the keys on the CIM shafts fell out on all of them almost every time we drove the robot.

They had to be cleaned with rubbing alcohol, but now we have the problem solved.