Old Tamiya pinions are 0.8 module, which is fairly close to 32dp. They're still currently used on thier cars like the Hornets etc.
True 32dp gears come in at about 0.794 module, which means theyre' probrably close enough to interchange given the tolerances in the RC10. After all, the whole spur does tend to float around on the diff balls from side to side a bit anyway...
The two naming conventions are actually not that hard to understand, but they work in totally differnt ways.
Diametrical Pitch (dp) is imperial. It basically relates to the number of teeth on a gear that is one inch in diameter. Simple. So if you have a gear that is 32 dp, it would mesh with a gear with 32 teeth that has a diameter of one inch. (Strictly speaking, the diameter is that of the "pitch circle" - an imaginary circle going through the points where the meshing gears touch)
Module on the other hand, is metric. It's calculated by the dividing the pitch circle diameter in millimeters by the number of teeth. Also very easy.
So, if you have a 32dp gear, it'd mesh with a gear that has a pitch circle of 25.4mm (one inch) and 32 teeth. 25.4 divided by 32 is very very close to 0.8 - so your tamiya 0.8 module pinions are prob fine.
As an aside, please note that the 0.5 module gears on most newish Tamiyas and the 48dp gears on many other cars are NOT very close and will likely cause problems. By definition, 48dp equates to about 0.53 module - not nearly as close a match.
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