I used these gears in addition to replacing 2 of the factory roller pins inside of the clutch assembly. Some of the factory clutches are mis-machined, causing the rear wheels to lock up. I replaced 2 factory 2.94mm pins with K&S 3/32" piano wire (2.38mm) giving more room in the clutch. Look on YouTube for Ego wheel videos and you will find my other account showing the fix.
