Gear Pitch Explained
Gear pitch is as important as pinion and spur size. Choosing a certain gear pitch can make your drive system smoother, or stronger, or less prone to damage, or easier to strip, or just plain noisy. In RC, there are generally three commonly used standard gear pitch measurements – these are 32-pitch, 48-pitch, and 64-pitch. There’s also other gear pitch measurements (i.e. Tamiya’s “module” metric pitch) which we’ll go over later.
First of all, what does the “pitch” mean? It’s pretty simple really. The term “pitch” is equal to the number of teeth on a gear that is 1″ in pitch diameter (not overall diameter). For reference, pitch diameter is the diameter of the gear about 1/2way down the side of a tooth. This is also referred to as the diametral diameter.
Back to keeping it simple, here’s what’s what:
32-pitch = 32 teeth in a gear that is 1″ in pitch diameter
48-pitch = 48 teeth in a gear that is 1″ in pitch diameter
64-pitch = 64 teeth in a gear that is 1″ in pitch diameter
EXAMPLE: Below is a 48-pitch gear. note the teeth size.
EXAMPLE: The gear below is a 64-pitch gear. Note how the teeth are smaller.
Tamiya uses metric pitch on some of their vehicles. Commonly referred to as “Tamiya pitch” they are defined as 0.4, 0.6, and 0.8 module. Unlike 32/48/64-pitch, metric pitch is formulated entirely different from “number of teeth”, but is a little too complicated to cover here.What isn’t complicated is how metric pitch and standard pitch are very similar (but not identical)
0.8 module is very close to 32-pitch. Likewise 0.4 module is close to 64-pitch – but also not exact.
EXAMPLE: Again, look at the pics below. The top gear is 64-pitch. The second gear is .04 module. Note how they look similar, but in fact they are NOT the same!
PAY ATTENTION HERE: The biggest variation is between 0.6 module and it’s similar (but far from exact) 48-pitch standard counterpart. Common sense tells you that it is never a good idea to mix standard and metric-module gears, but because 0.6 module looks visually the same as 48-pitch, some people inadvertedly mix the two and wind up with grinding (and eventually stripped) gears.
So what pitch should you choose? First let’s run down the pro’s and con’s. We won’t go over 32-pitch here because 32-pitch is only common in nitro or larger scale vehicles. Let’s just cover what we mostly use in touring car racing, which also can be applied to RC drifting:
48-pitch
+ larger, stronger teeth
+ less sensitive to gear mesh
+ won’t suck up rocks as easily
- larger teeth surface contact means more noise
- gear ratio range is smaller than 64-pitch
64-pitch
+ more teeth per diameter than equivalent 48-pitch gear
+ smaller teeth surface contact means less gear noise
+ finer gear ratio adjustment
- more sensitive to gear mesh
- more prone to picking up small dirt or dust
48-pitch is more common in off-road vehicles, where dirt and other contaminants, and more “drivetrain shock” are more common. 64-pitch is seen mostly on on-road vehicles, where fine adjustments to gear ratios are preferred, and a quieter drive system is more efficient.
However, since most RC drifting takes place in random places with varying conditions, using 48-pitch is a safer bet. While 64-pitch can be used in RC drifting, 64-pitch (and it’s finer teeth) are more suited to fully prepared surfaces, such as carpet or dust-free concrete.
As for Tamiya’s 0.6 module, they share the same pro’s and con’s as 48-pitch; the only factor making 0.6 module not as popular is that you don’t have as many spur and pinion gear size choices as you do with standard 48/64-pitch. For some vehicles that can’t be converted to standard pitch (i.e. Tamiya’s TT-01) 0.6-module is your only option. Therefore when buying gears, make sure you have the right pitch!
Sample drift vehicles and their box-stock gear pitch
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Associated TC3 – 48p
Associated TC4 – 48p
HPI Sprint 2 Drift – 48p
HPI Pro 4 – 64p
Hot Bodies Cyclone – 64p
Hot Bodies Cyclone-S – 64p
Tamiya TA-05 – 0.6 module
Tamiya TT-01 – 0.6 module
XRay T2 – 64p
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