The gear ratio is a very important setting not only for the behavior of your RC car, but also for the proper durability of your equipment.
The total gear ratio is often written in the descriptions of the various vehicle. But it depends on the ratio of the gearboxes for a 4wd buggy, or of the gearbox for a 4wd buggy, as well as the ratio at the engine/motor output.
Two cars with identical gear ratios will not behave in the same way if the transmission ratio inside the bulkheads or to the engine are differents.
In fact, if the ratio in the bulkheads is short (e.g. the IFW618 and IFW619 options for Kyosho MP10) you car behavior will be more aggressive, reactive and maybe oversteering. This is not necessarily what many drivers are looking for in their basic setup for RC cars, in search of fun and ease of use.
What is a short ratio?
A short ratio is a shorter gear ratio, by definition a lower output rotation speed for the same input rotation speed.
Here's an example:
- Car with 46-teeth ring gear and 16-teeth pinion: ratio 46/16=2.875
- Car with 46-teeth ring gear and 15-teeth pinion: ratio 46/15=3.067
The car with the 15-teeth pinion will be “shorter”, as the gear ratio is bigger.
A shorter ratio will result in a more responsive car, but with a lower top speed.
On the opposite, a longer ratio will give you more top speed but less responsive acceleration (smoother).
Beware of electric brushless cars, however, as a bigger motor pinion (longer ratio) will lead to an overall increase in power, as motors are very powerful these days.
For further explanations of the differences between ratio in the drive trains or in the center, and the difference in the effect of ratio on electric brushless and nitro buggies, take a look at our video tutorial:
VIDEO
See you soon for a new episode!
The Shark
Reno Savoya