Chuck Kimbrough designed our tooling. With more than 30 years of plastic gear mold experience and more than fifteen years of experience racing R/C cars, Chuck knew what it took to make the best R/C car racing gears.
The tooth shapes of Kimbrough Racing Products gears are cut with state of the art, Wire Electronic Discharge Machines (EDM). Particular attention is given to plastic shrinkage and gear backlash.
Kimbrough Racing Products gear molds are built with the gates (the spot where the hot plastic is injected into the mold) in the center hole. This allows for more even plastic flow throughout the mold cavity, so as it cools and shrinks, it makes the gears consistently round and concentric.
Kimbrough Racing Products gears are molded from 4/6 Nylon. 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 Racing Products gears are molded with black plastic, because as any radiator engineer will tell you, black dissipates heat into the air better then any other color - and high temperatures are not good for thermo-setting plastics.
Kimbrough Racing Products gears are not molded with large open holes to save weight and plastic because Nylon absorbs and releases moisture. Depending upon the amount of moisture in the atmosphere, it will shrink (in dry air) or grow (in wet air). If a Nylon gear has large open holes, it will become out of round if it doesn't have the same amount of moisture it had when molded. Besides, Nylon is such a light plastic that solid Kimbrough Racing Products gears are less then .5% heavier than the lightest gears on the market. If you consider total rotating mass weight (motor-armature, wheels, tires, etc.), this slight weight difference becomes insignificant.
Kimbrough Racing Products gears have 12 diff. ball holes for on-road cars. 12 balls distribute the load on the Diff. washers better then 6 or 8 balls. This makes the Diff. washers last longer and the Diff. feel much smoother as well.
Kimbrough Racing Products gears have a ring molded around the ball holes for our snap on Diff. Covers (# 140). This helps to keep dust and dirt off the diff. balls.
Kimbrough Racing Products gears are full width. We do not make narrow or profiled gears because plastic can deform under load. This can cause drag in the gear train and waste horsepower. The wider a gear is, the more load it can take. The only time gear engineers narrow gears, is where there are space limitations. Narrow or profiled gears are weaker and less efficient. Kimbrough Racing Products gears run quiet because they have the correct tooth shape and don't have to be narrowed. We also highly recommend the use of full width pinions gears.
Kimbrough Racing Products Plastic Gears have been used to set all of the unlimited speed records for R/C 1/10 scale electric cars in the U.S., and are used by a large number of the top professional R/C car racers around the world.