I don’t know what it is but there’s something in me that will just not allow anything to remain in stock form. This includes the LEGO Passenger Train. The LEGO Train is a great toy for younger kids really exposing them to many different useful life skills. They learn to read instructions and convert this to actions. Toys that provide this type of learning, is always something that is perfect in my books. What does this mean? We need to get one. Just blame it on the kids, you know you will love it too!

Why Convert the LEGO Passenger Train to RC?

It’s quite simple actually. Many hobbyists have parts in their bins that aren’t being used. The LEGO Train is a perfect candidate to parts that are otherwise just collecting dust. More specifically, converting the Passenger Train over to RC will unlock so much potential. The LEGO factory controls called “Powered-Up” have limited speeds that the Train can be operated at. The level of precise control is lacking. Upgrading the unit to Hobby Grade RC equipment can provide many benefits in this regard.

What Features will RC Equipment Provide?

As mentioned above, the biggest advantage of RC equipment is the full range of throttle. In other words, we will have the ability to input a throttle command between 0-100% resulting in virtually limitless control. Our train will have the potential to apply brakes. Imagine how useful this can be when you would like to travel down along a negatively sloping section of track. Brakes will allow the train to come to a full stop. In addition, the train will continue to have a reverse function, however, the function will have 0-100% throttle in the reverse direction. This is unlike the stock train that has a limited number of steps.

Most Cool RC Train Feature

The feature that I am most excited about is the ability to program in “momentum.” Rather then allowing the train to accelerate instantaneously, a delay can be setup to mimic the train having a lot of weight. This will help for two reasons. First reason, well, it’s more realistic while accelerating and decelerating. Second reason is without the delay or some control, the train would be fed enough power to do a burnout down a 6 foot section of track before finally hooking up and getting to top speed. To remove this as it could be a costly wear item, simply just program in a throttle delay.

Other Small Features

Other features such as limiting the potential top speed will be easy to do. For those of you that know RC fairly well, this could easily be done with EPA’s of the throttle channel.

I will be adding a timer that will display how long the train has been power for that specific run. Everytime the train is stopped, the timer will also stop. For every minutes there will be an audible call-out. Having a throttle kill switch or an “arming” switch is possible but totally not needed. In fact most of all of this is not needed but that’s not at all the point.

Features that could be added to the LEGO Train Soon

There are a bunch of features that could be added later. This includes telemetry data as an example. Imagine having the ability to take a look at the voltage of the train when it is underway. Better yet, upon certain levels of voltage, the percentage of battery remaining is called out. This can quite easily be setup with the right hardware. Even telemetry that monitors speed, location and direction can be added. Many more options similar in nature are possible.

Don’t forget to watch the video of this RC Lego Train

Hardcore RC car enthusiasts are always looking to push the envelope. A big part of doing this is understanding what is happening within the power system. Without this level of understanding it is very easy to get yourself in trouble and that’s when your power system starts smoking. Something to avoid at all costs!

The largest challenge in RC is how can we understand or better predict the amount of current that our cars need? Therefore, we are going to discuss why it is difficult to predict how much current an RC car motor will draw. Also, why is this more difficult than predicting current draw for RC airplanes.

The three main components in an RC Car

To demystify the mechanics behind the current pulled, let’s introduce power system components and their respective specifications. This will serve as an example for our RC car.

LiPo Battery

First off, the LiPo battery (lithium-polymer battery) has its specifications typically marked on the front of the battery. In our example consider the specification of 77A (2.2Ah x 35C continuous rated). This 77A figure identifies the amount of current that the battery can generate.

Electronic Speed Control

The electronic speed control (ESC) has its rating also marked right on the front of it. In our example, let’s consider a rating of 60 amps. This is the maximum continuous current that it can support.

Brushless Motor

Lastly, the brushless motor has it’s specification accessible from the manufacture’s spec sheet. Consider our example to be able to deliver approximately 75 amps of current.

What do these Specifications Mean?

This is the exact question, what significance do these specs hold in terms of determining how much power this motor can draw?

A clear and concise answer to this: None.   

Despite these specifications, we are clueless as to how much power our brushless motor is going to draw.

Not that it is completely impossible to determine how much power brushless motors can draw. We can check that with a dynamometer for measuring mechanical power generated. We can gauge the amount of power that the motors are generating, the current being drawn and the amount of electrical or mechanical power being consumed or given out with the dyno.

With these values, we can depict the amount of current that the motor drew for a specific load of the motor.

Doesn’t this sound so easy? Nope, not at all.

Load on a Brushless Motor

The load refers to the amount of current drawn and is arguably an important part of the system. The actual current that the motor will pull comes from the Io value. (no-load value) Essentially the current drawn at zero load. Simply put, the Io value is a waste of energy since you won’t get any mechanical torque from the motor.

Interestingly, once the motor is loaded, (using a propeller) the current value starts increasing past the Io value. Which is about 2-3 amps for the motor used here. Then we increase the load further by placing a larger propeller onto our motor and skyrocketing the current up to 30-40 amps. Remember that the bigger load is represented by the bigger propeller used.

The point we are trying to make here is that as you increase the load on your motor, without interrupting anything else, the torque output of the motor must increase. The load is quantified as mechanical torque required by the motor. The translation from mechanical to electrical is torque being equal to current drawn. As torque output of the motor increases, the motor will draw an increasing amount of current.  

The Difficulty in Determining Torque / Current for RC Cars

If life were simple, we would be easily able to predict the torque output of a motor. But, that’s not how it goes. There are so many factors or variables to consider that make up the torque requirement and thus current draw.

How about an online calculator? Although there are online calculators for RC airplanes or EDF jets, there is no such calculator for an RC car.

Why?

Let’s Discuss Influencing Factors

Because there are more factors involved in this type of situation than one can imagine. For instance, consider placing a brushless motor in an RC car and drive it at constant speed. There would be a significant difference in the power required to drive at constant speed vs accelerating up to that speed. Even if the RC enthusiast were to accelerate lightly vs aggressively, there would be a considerable difference in the amount of current being pulled[RT1] .

Similarly, if you opt for a larger tire, the same effect would be noticed. When we alter the RC car, by increasing load, we are asking the motor do more work. Even if we don’t alter the RC car, and drive it on grass, we would notice that the grass would cause the motor to load up. This is due to the friction between the tires and surface, causing the torque to rise.

Another example that can influence torque required is a strong headwind or tailwind. The greater the headwind speeds, the greater the amount of power required to penetrate the wind. The amount of current drawn is very difficult to estimate.

After all of this where do we go from here?

There are a couple means of determining how much current your system will draw. The best way is to place a datalogger within your RC Car and record the amount of current your system pulls. The big down side to this, is of course, it’s not a prediction. You at this point would already have all the components.

To make the best prediction, we recommend doing a bit of research on the internet. There are more than likely many RC enthusiasts out there with the same RC vehicle as you and based on their power system and results, you can gather data and expectations. If you can’t find someone who has the same power system as you, choose the next best thing. That is the most similar power system you can find.

Key Takeaway

First, the specifications of your RC car’s motor won’t tell you anything about how much current it will pull.

Secondly, the load that you place on your motor, determines how much power or current the motor will essentially draw. Thirdly, the load equates to the amount of mechanical torque required by the RC car.

Lastly, it is possible to predict the current drawn by utilizing someone else’s experience. Find another system out there that most closely matches the one you plan to use.

We hope this was an informative guide for you to understand these challenges and how to better overcome them. Be sure to check out the YouTube video here for more detail.

RC cars are not everyone’s thing – especially those who would rather drive slow and steady. Those who prefer racing over a slow drive, fuel their spirits with speed and thrill. Therefore, today we will be discussing a high-performing RC car motor – Castle 1721 2400Kv.

The 1721-2400Kv motor is exclusively for those who get want to upscale their RC racing game.

But do you know what makes the Castle 1721 2400Kv the fastest RC car motor?

If not, in this article we will be discussing, step-by-step, the features of the Castle 1721 2400Kv motor.

Castle 1721 2400Kv comes without a warranty

Every electronic product bought online comes with literature, just like with the Castle 1721 2400Kv motor. The product usage warning is helpful in knowing how to use that item and warns you of damaging the item. This is the case for most items, however, in the case of this Castle 1721 2400Kv motor, the warning states that there is no warranty with this product due to the extreme nature of the motor.

This is the first alarming point.

In fact, it states that there is no warranty for ANY Castle electronics, including the ESC when used with this motor – that’s how powerful it is.

Even if we connect this motor to any random battery back, it may also not have a warranty.

Why, though? Well, for that you can go over the product warning literature that comes with the Castle 1721 motor. But take this is as the first sign as to why this motor is ridiculously insane and fast. The fact that it’s such a beast of a motor, maybe it does not even need a warranty?

Now, let’s talk about the actual first point as to why this motor is so insanely fast.

Size Comparison of the Castle 1721 2400Kv

The Castle 1721 2400Kv motor is designed for radio control cars of the 1/8 or 1/7 scale. If we compare this motor with another motor of the same scale, there is a very noticeable difference in size. The Castle 1721 motor is not only double the size of the motor that we compared within our YouTube video. (Castle 1512 2650Kv) But it can be the perfect 4s-8s motor for any RC 1/8 scale RC.

Apart from the length, we noticed that Castle 1721 has a larger diameter than the other motor. Though this may not seem like rocket science for most RC enthusiasts, it is important when discussing the power-packed performance of the Castle 1721 2400Kv motor.

Moving on, the following two features of this RC car motor are worth mentioning.

These two features are what set the Castle 1721 motor apart from its competitors. We did a little comparison, which can be seen in the YouTube video here.

Comparing RC Car Motors

Since we have no warranty on the Castle 1721 motor, we disassembled it and revealing the inner workings. You can check out the full video of disassembling it here.

Once the screws are off the front cover, we pulled the rotor out of the motor, exposing the insides.

It is noticeable here that the screws don’t go into the body of the motor to help center the shaft similar to the 1512 motor. It is the end caps embossed feature that pushes in to the motor can to center the shaft. Then the screws just make sure nothing comes apart.

Next, we pulled out the rotor from the brushless motor, and this is where we noticed a significant difference between the Castle 1721 2400Kv motor and the other one. Keep in mind, the motors must be placed at a distance apart to prevent them from snapping into each other as there is a strong magnetic force.

Stainless Steel Sleeve

With the 1512 and 1721 motor now apart, we noticed the kevlar wrap on the 1512 motor. You can see the wrap around the rotor of the motor. This is what indeed makes the rotor hold its contents intact. Without the Kevlar wrap around the motor, the magnets, after speeding up, would have destroyed the motor.

In fact, the Kevlar wrap limits the motor to 60,000 RPM, approximately the size of the smaller motor that we used for comparison. This is why the Castle 1721 motor is different – there is no Kevlar wrap around its magnets and you probably cannot even tell if the magnets are there or not.

The Castle 1721 motor has a stainless-steel sleeve inside that encapsulates the magnets and prevents them from flying out of the rotor’s core. The stainless steel sleeves help in increasing the holding strength of magnets and prevent them from ejecting from the rotor. This way the motor reaches up to 90,000 RPM, making the Castle 1721 a high-performing motor.

Now let’s discuss the final feature that makes the Castle 1721 a ridiculously awesome motor.

Windings inside the RC Car Motor

Although the structure of windings is not visible inside the RC car motor, we know that Castle markets this motor as a 0.5Y wound motor, and that is a very significant feature.

This significance lies in the fact that typical Castle motors of the 1/8 scale or larger have all been 1Y wound brushless motors. The wind is what allows the user to maximize the total amount of RPM in the RC vehicles.

To explain this phenomenon even further, let’s develop a hypothetical situation. Suppose that this Castle 1721 motor was actually being sold as a 1Y wound motor, what would that imply?

Knowing that the 0.5Y is actually 2400Kv, a 1Y is going to be 1200Kv. So, in order for us to maximize on the total amount of RPM, 8s, the maximum voltage that this motor can work very well with, won’t be enough for the 1200Kv motor to make use of the 60,000 to 90,000 RPM range.

To actually do that, we would have to go to 16s, instead of 8s, which is not very practical. Therefore, it is more convenient to use 8s. As for our 0.5Y wound motor, since we do not need to double voltage what we get in return is the potential to double current! This means we can run 8s voltage but pull easily double the current that any other 17 series motor can handle. Think about that for a moment!

Once you go below one turn, the winding essentially becomes a competition type wind. This really just means they produce a lot of power by utilizing a ton of current. This is why you get a warning label with the motor, making sure you know what you’re doing with the motor.

Final Thoughts

That’s it for the different kinds of warnings on the Castle 1721 2400Kv motor and why we don’t have a warranty with any castle products. This motor is an absolute Beast. Don’t be surprised if this motor pulls over 500A under heavy acceleration on 8s. It is very well capable of these power levels. (>15hp) That’s what makes this motor such a beast of a motor.

Owning an RC car has become the talk of the town in recent years. That’s because driving an RC car is fun whether it is a hobby or for racing. Whatever the intent behind owning an RC car, learning about its technicalities should be a priority. Sure you would know which model to buy, equipment to purchase, but do you know which gearing mistakes to avoid?

I guess not.

Maybe that’s why you clicked on this article or searched “RC car gearing mistakes to avoid”. Nonetheless, this article will outline the four common RC car gearing mistakes that many users make. We will talk about each of these in detail and tell you how to avoid ruining your precious RC car.

Pitch of the RC car gear

As most car enthusiasts know, gears are essential for optimizing torque and speed. Now let’s talk about how messing with the gear, or particularly its pitch can cause problems for an RC car. Let’s first take a look at the two standards for gearing – the imperial standard and the metric system.

Differing gearing standards

32 pitch and 48 pitch are the common gear pitches in the imperial standard. The metric system, on the other hand, terms pitches as metric modules. 0.8 metric mod, or 1.0 metric mod, are examples of pitches in the metric system.

The peculiarities of the imperial and the metric system don’t end here.

It is advised not to mix the imperial and metric standard gears. The only example where it can work is using 32P and 0.8M. There are a lot of RC car drivers out there mixing these two gearing standards. Although not recommended, this can work relatively safety with no issue only because the pitch between the 2 different system are less than 1% different. Let’s take a look at the problems that could occur from meshing gears from the two systems outside of this one instance.

Signs & Symptoms of using two different gear sets

Extreme wear of the gearing will occur when two different sets are used – one from the imperial system and the other one from the metric system. More than likely, you won’t even be able to mesh the gear sets!

Key Takeaway

Gearing sets from different standards is simply bad practice. Problems with meshing two different gearing sets lead us to the next mistake which involves incorrect gear mesh.

Setting the RC car gear mesh correctly

Setting the gear mesh properly is as important as keeping in mind not to intertwine two separate gearing sets.

Incorrect placement of the RC car gear mesh could lead to unnecessary damage in the form of wear and tear on the components of the car.

Tight gearing mesh

If the mesh is placed tightly, this can cause binding, which is noticeable due to the noise in the gear train of the RC car.

Even a tight gear train can cause noise and wear. “So, what if there is a little bit of noise or wear and tear, isn’t that common?”

Truthfully, no.

Primarily, the increasing noise and abnormal wear of the gearing would consume more power than usual. This would also cause more heat generation in the gearing system and also unnecessary heat build up in the power system of the RC vehicle.

Not dealing with the frictional increase and wear and tear timely can destroy the teeth of the gears. On the other side, loose gearing can also be a problem.

Loose Gearing Mesh

A gear that is less tight than usual can result in three main problems

• Increased backlash – a transverse movement between the gear teeth at a pitch circle that can result in noise, weakening of the gear, and abnormal wear
• Possible gear failure due to the increased backlash
• Possible stripping away of gear teeth due to excessive stress caused by reduced meshing surface area.

Key Takeaway

The gear mesh should neither be too loose nor too tight. Make sure to space the gearing appropriately avoiding setting the mesh incorrectly.

Loose Fasteners in an RC car motor mount

Trying to mesh an RC car’s gears appropriately is one job, but making sure its fasteners are not too loose, is another, and in fact, a very important one.

If you have a brushless motor mount or nitro engine mount where its fasteners could come loose, this is where bad things can happen. When fasteners loosen up, the gear mesh on your RC car begins to increase and become loose. This is an easy way to completely strip out the spur gear, especially if it is made out of nylon material and not steel. Using a lot of torque on these fasteners is not always good enough. It is recommended to use a type of thread locker to ensure that the gear mesh does not loosen due to fasteners coming loose.

Key Takeaway

It is recommended to use a thread locking compound to avoid fastners loosening up and causing you some major gearing issues. When you need to remove the fasteners to change gearing or reset mesh, just simply apply some heat to the fasteners with the locking compound to break the bond and allow you to remove the screws more easily.

Gear Ratio vs. Heat of the RC Car

One of the potentially most harmful situations for an RC car would be overheating, as this would disrupt the functionality of the power system.

But how does one know the temperature of the RC car?

This can be done by measuring the temperature of the brushless motor, the speed control, and the battery pack within the RC car. While measuring the temperature, it is crucial to assess that the temperature readings are within their specific parameters. Find these parameters in the manufactures manual or instruction sheet. Knowing this margin will help the RC car driver in assessing when to change the gear set for better thermal performance.

Key Takeaway

After the installation of the new gearing system, note down temperature readings at specific time interval to avoid the risk of burning out any components. Run the RC vehicle for a minute and then note down the temperature. This would help in finding out the maximum temperature of the RC vehicle. If temperatures are too hot, use a motor pinion gear with a smaller tooth count. Another option is using a spur gear with a larger tooth count. The result is reducing the load of the motor decreasing temperatures in all power system components.

Final words

Hopefully, this article provided useful information for new and experienced RC car enthusiasts. Though the list of mistakes made by RC car drivers is not exhaustive, these are some of the most common and most likely avoidable ones.

For an audio-visual experience of these geeky insights, check out the video on our YouTube channel here. What do you think about these mistakes – common or not? Let us know in the comment section on the video. Also, tell us which other loopholes you might have discovered in your RC car journey.