In brief, RC Cars utilize a transmission that contains a gear set. Different applications will require different “pitches”. A gear pitch given in imperial terms is related to the amount of teeth that would encircle a one inch diameter. This one inch diameter is known as the pitch diameter. The metric module is how pitches are defined in the metric system. The metric module is known as the ratio of the diameter of the pitch circle per tooth. Do not confuse the metric and imperial pitch sizes as they represent different sizes of pitch.
What Gear Pitches Exist
In particular, there are both metric gear pitches and Imperial gear pitches used in RC cars. Below is a list of the common gear pitches used:
Imperial Gear Pitches:
- 32 Pitch
- 48 Pitch
- 64 Pitch
Metric Gear Pitches:
- 0.5 Module
- 0.8 Module
- 1.0 Module
If you are unsure of which pitch your specific RC car vehicle uses, look up the parts in your manual. In any event that you can’t find the pitch of your spur gear or pinion gear in the manual, try out the gear pitch calculator.
As the imperial gear pitch increases, the size of the teeth and gear actually decrease. They get smaller. Furthermore, as the Metric Module increases, the size of the teeth and gear increase. Hence, the gears and teeth get larger
Can you Use a Metric Pitch in Place of an Imperial Pitch?
A Metric Module of 1.0 converts to an imperial pitch of 25.4. Gears with a Metric pitch are not designed to match an imperial pitched gear. I would recommend not using a metric pitch in place of an imperial pitch. In short, this does not mean that you will never find a combination that is close enough to substitute. One could argue and even use a 0.8M gear in place of a 32P gear and it may work well. Even so, I would not recommend using the pitches interchangeably unless you are OK with an increase in gear wear that could result.
Why Use Different Gear Pitches?
Not all applications are alike, this is why we must use different gear pitches in RC. Generally speaking there are two main reasons to use a different pitch. The first reason being physical size. If you are operating a smaller indoor 1/18 scale RC car, it is not ideal to use a large gear with a big pitch. The size of the gear would be far too big to place in to the RC car. It’s also worth it to point out that moving to smaller gears also allow for a decrease in friction allowing more power to make it to the wheel. This is also important for smaller RC cars in order to get the limited power they make, to the ground more efficiently.