Kimbrough Products 48 Pitch spur gears are molded with black 4/6 Nylon plastic because black dissipates heat into the air better than any other color - and high temperatures are not good for thermo-setting plastics. This plastic is almost three times tougher and will withstand operating temperatures 75° to 125° higher than plastics used by other R/C car gear manufacturers.
Kimbrough spur gears are full width because a narrow or profiled plastic gear can deform under load, is weaker and less efficient which is why we recommend them with our 48p 5mm bore drag race pinions. This can cause drag in the gear train and waste horsepower. The wider a gear is, the more load it can handle. The only time gear engineers narrow gears is when there is a space limitation. Kimbrough Racing Products gears run quietly because they have the correct tooth shape and don't have to be narrowed. Choose from a variety of tooth count choices to allow you to fine-tune the torque and top speed of your model.