Hardened Steel Pinion Gears are designed to work with our Hardened Steel First Gears as well as stock Power Wheels, Kid Trax, and other vehicles with 32 pitch First Gears. You MUST use Hardened Steel Pinions with our Hardened Steel First Gear.
Aluminum pinion gears work with stock Power Wheels, Kid Trax, and other vehicles with 32 pitch First Gears. They are less money and cuts down on rotating mass.
Use threadlock on the set screw to keep it from backing out.