Suggest to add lubricating oil, it can be reduce the friction between the metal gears, also the sound will be smaller when it is running.

The gear set compatible with Traxxas Rustler 4X4 / Slash 4X4 Platinum/ Slash 4X4 Ultimate/ Slash 4X4 VXL / Slash 4X4 / Stampede 4X4 VXL /Stampede 4X4 1/10 RC car truck
The 6878 differential gear and pinions gear are made of quality metal material, durable and lasting-performance.
Come with 5mm to 3.17mm coupler to convert the installation apertures,so that it can be works on the 5mm or 3.17mm motor shaft.
The 3 different teeth pinion gear will makes more choice in gear ratio in order to achieve the different rc car 's speed.
Effectively improve the performance of your car.
Easy to install,a great replacement part for the old or broken one.

Item Name: 54T 32P Spur Gear with 15T/17T/19T Pinions Gear Sets
Material: Steel
Spur Gear Teeth :54T 32P;
Spur Gear Outer Diameter:45mm

Motor Gear Teeth:15T/17T/19T 32P
Motor Gear Innner Diameter: 5mm

Package List:
1 x 54T 32P Spur Gear
1 x 15T Motor Gear
1 x 17T Motor Gear
1 x 19T Motor Gear
3 x 5mm to 3.17mm Coupler
3 x Grub Screws