INJORA Overdrive Underdrive Alloy Steel Helical Gears for 1/18 TRX4M
Suit For: 1/18 RC crawler TRX4M
Note:

Each axle requires 1 set of gears (a ring gear and a pinion gear).
Overdrive the front(or underdrive the rear) will pull you faster in the front, it allows you to climb better and reduce rollover.
Do not swap gears from different gear sets! They are different even if they have the same number of tooth.
If you have some free play between gears, you can add a shim or 2 between pinion gear and bearing to push pinion teeth deeper into ring gear teeth.
22T/10T Underdrive Gears: Decrease speed approx 9%
24T/10T Underdrive Gears: Decrease speed approx 16.67%
24T/12T Gears: Do no change speed
22T/12T Overdrive Gears: Increase speed approx 9%

Features:

Replace the stock plastic gears, fit TRX4M front or rear axles
Helical gears offer greater strength and smooth operation than the factory spur gears
Less vibration, less noise, less wear then stock gears
CNC machined 20CrMo Alloy Steel Gears

Specifications: