How to adjust gear ratios and slipper

Making adjustments is a common thing you have to do on your RC car in order to get the best possible results out of our model car, be it on the race track or just while cruising the streets to have fun. Some of them are easy to do and really essential, just like the adjustment of your gear ratio (spur gear/pinion gear) or the adjustments of your slipper clutch. These are one of the most common ones you will be making.

First of all, let’s see what in fact you need to change before you actually do it. The drivetrain is composed out of the gears, vehicles, and axles of an RC car. The spur gear is one of these gears which are a part of the drivetrain and it meshes with the pinion gear on the electric motor, if we’re talking about an electric RC car, and on the clutch bell of a nitro engine if we are considering a nitro RC car.

The pinion gear is an important component of the drivetrain, which attaches itself to the shaft of an electric motor. This tiny piece meshes with the spur gear in order to provide more power to the drivetrain.

Last, but not least, the slipper clutch will protect your drivetrain from damages or excessive wear, because it allows the spur gear to slip when the engine delivers more power to the gears and wheels.

Now that we figured out the basics of this system, we can move on to those adjustments that make your life much easier when you’re out on the track! How do you find the right gear setup on your RC car?

A correct setup will help with speed and power and some settings might be able to give you that extra edge on the track and help you beat more powerful cars if their gear ratio is not quite right. The first thing in optimizing gear ratio is actually calculating it on your RC car. A numerical combination, based on the pinion/spur gear combination, is seen like this: 22/88 or 23/90. These figures are actually the report, the ration between a 22 tooth pinion gear with an 88 tooth spur gear. The gear ratio is actually calculated by dividing the number of teeth in the spur gear to the on in the pinion gear.

For nitro vehicles, you can increase or decrease this value by changing the size of the clutch bell gear. Once you’ve determined your car’s current ratio, you should begin the quest for the perfect one. Some manufacturers give this combination on the kit, but the best way to find it is the classic “trial and error” method. Go out on the track and try out a bunch of combinations in order to see for yourself which is best. Use a series of 5 minutes runs with different gear ratios, starting from the lower ones, and time them. Increase the gear ratios and run again. Repeat this process until the performance falls off, then you can get back to the ratio which had the best performance.

Remember that the gear ratio is not an independent setting and that it is a part of the system. So, a regularly used gear ration can cease to be the right one if you don’t take power into consideration. For example, if you upgrade to a more powerful engine, the former gear ratio might not work so well like with the previous engine. The result would be that you can’t get the best out of your new engine. Also, different track surfaces can increase or decrease power. For a smooth and slick surface, you may need one gear ratio, but when you switch to another surface you might find that the engine is overpowered. An increase in gear ratio can smooth things over and offer a more smooth acceleration.

The slipper clutch is another part of this setting. This adjustment is used to fit the type of track you are running. For a short track, you may need to tighten the slipper, in order to give a bit of edge around corners. Loosening the slipper is better for longer tracks because it helps you maintain some consistency on the track.


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