Brushless motors in the lego world - general topic

[HorcikDesigns]

Hello Brushless motor fans, 

I am back with new 3D printed accessory for our MOCs. 

This time it is compact 33:304 (approx. 1:9) gear ratio gearbox. 

Files available for free download: 

https://makerworld.com/en/models/1908460-gearbox-for-custom-motor-for-brick-models#profileId-2046273

It was designed as evolution of my previous motor-to-bricks adaptor, so they use similar parts. I also tried to make it very compact with good variety of attachment points

Originally it was supposed to allow gear shifting, but it seemed as too complicated for now. 

In future I would like to make more versions with different gear ratios. This one is very slow. 

It uses module 0.8 and 1 gear teeth, so you can use standard 20t LEGO wheel and some pin connectors as output instead of the printed parts, if needed. 

Questions? Ideas for improvement? 

[everybrickasculpture]

Looks great, I can't wait to try a few of them out.  I have made six of your inline brushless motor which have been excellent, so I'm sure this one will be too.

[gyenesvi]

14 hours ago, HorcikDesigns said:

I am back with new 3D printed accessory for our MOCs. 

Looks really interesting, solving the down-gearing without huge gears that would result in loosing ground clearance at the bottom, totally like in an RC transmission, nice!

I wonder how those printed gears will hold up!? In your previous model, did the gears wear a lot at the teeth?

Also, I don't get how a 1:9 down-gearing can be too slow for you, I can't even control my 1:24 :) What's the kv rating of that motor you are using?

At the output, is there an axle hole inside that tube?

[HorcikDesigns]

@everybrickasculpture. Wow, thanks. :D

@gyenesvi@gyenesvi yes, keeping the ground clearance was my intention to improve from the previous model. Well, the gears are still plastic, and they can be easily re-printed when needed.

After that transmission gearbox I have planetary hibs in wheels, so that makes addotional reduction. Originally I have used 1000KV motor, then tried it with 2000KV which seems OK. I would like to keep the RPMs as low as possible to minimise the wear of the parts. 

Of course, there is axlehole inside the output. However, there is round hole on the end to allow new CV joints to be inserted flush with the pinhole matrix. 

[gyenesvi]

1 hour ago, HorcikDesigns said:

 

After that transmission gearbox I have planetary hibs in wheels, so that makes addotional reduction. Originally I have used 1000KV motor, then tried it with 2000KV which seems OK. I would like to keep the RPMs as low as possible to minimise the wear of the parts.

Oh, I forgot, using the planetary hub explains the slow speed :)

1 hour ago, HorcikDesigns said:

Of course, there is axlehole inside the output. However, there is round hole on the end to allow new CV joints to be inserted flush with the pinhole matrix. 

That's a nice design, sounds compact as well!

[HorcikDesigns]

Yes, it is designed to take up only 32mm (4L) of space. 

[keepbricking]

hello guys 

can anyone install ldview and the ldraw parts library and see if it is working for them

then you can get most of the lego part .stl files

please , i would be very grateful , i might even pay you

this reddit post shows how to setup everything

https://www.reddit.com/r/bioniclelego/comments/12circd/a_guide_for_getting_stl_files_for_3d_printing/

 

[Krzychups]

Hi everyone! I've finally menaged to make an in-wheel-drive Lego RC car!

I use the Hobbywing Xrotor G2 45A 4-in-1 ESC and 4108 drone motors. The start-up is very smooth, it has outstanding acceleretion. It's silent, you can only hear spinning tyres. The car is very stable itself. I use soft tyres as @Aurorasaurus has suggested and they absorb some of the overload. Suspension has a super damping, it works great! The car has a tendency to brake suddenly, so I cannot quickly slow down the throttle. 

When it comes to the suspension, I use 80 mm Injora shocks, 3D-printed wishbones and motor hubs. I designed the beadlock rims so that they have two parts that screw together. It's not the best rim design, but I didn't want to glue the tyres.

Regarding the front hubs, I use HSP 02038 ball head screws.

Spoiler

Other photos: 

Spoiler

I'm really pleased with the car. There's a mess with those cables, not going to lie. Maybe I'll tidy it up sometime.  Unfortunately, I don't have a video. I'll upload one in the near future. 

 

On 10/21/2025 at 9:25 AM, HorcikDesigns said:

This time it is compact 33:304 (approx. 1:9) gear ratio gearbox. 

Really nice gearbox! Why one of the gears has such a non-standart hole?

@gyenesvi, good job with your motors!

@vergogneless, I really like your car with 3D-printed parts. I'm sure that this will help with the car's durability. Isn't it a bit too much of 3D printing for a Lego car? 

Edited October 22 by Krzychups
Forgot to add some information

[HorcikDesigns]

 

@Krzychups The wierd hole is previous version of coupling with the output shaft. It had to transfer the torque (thus not circle), and help with centering and alignment of cross axle inside the output shaft. Before releasing the file (but after photo session) I realized that square hole will serve this purpose much better.

And good job with the car! Do I see right the in-wheel motors?

[gyenesvi]

On 10/22/2025 at 6:49 PM, Krzychups said:

Hi everyone! I've finally menaged to make an in-wheel-drive Lego RC car!

Nice car design, curious about the footage! Can you show more details of your suspension arm design?

I guess it's hard to draw the line where it becomes too much of printed parts to call it lego.. I guess as long as the spirit remains the same, that is building things from reusable parts, it's quite arbitrary which parts are official and which are not. But I'd agree that in @vergogneless's design there are many purpose made parts that would not be reusable for too many other things..

Edited October 24 by gyenesvi

[keepbricking]

well, seems like no one is going to help me anyway

btw @Krzychups what is the battery you are using and what is the total power of the car, do you know how fast it goes, also what is the weight?

seems like IWD is the way to go 

i have all components but I have a drone stack ( flight controller and esc)

how do you program the flight controller?

i have tested it and the issue is:

when you are at zero throttle and arm,the motors spin very slowly

but even if you up the throttle just a tiny bit the motors continue speeding up, this can damage both the motors and esc

I did some research and found out that the esc speeds the motors up until the fc reports an increase in altitude(it is for drones anyway)

so my question is , how do you overcome this?

[vergogneless]

For my part, I consider that even with a large number of highly specific printed parts for a particular model, everything is used with the ultimate goal of being in harmony with the Lego system. I find this to be a great compromise to stay within the Lego world.

In my case, this allows me to build sturdy, robust, and durable mini 4x4s with a Lego aesthetic, which for me is an integral part of my enjoyment.

However, it’s always more challenging at smaller scales to combine performance and robustness while prioritizing pure Lego.

That being said, I invite you to check out my thread, where I’ve just presented my first two 4x4s in a bit more detail 

[keepbricking]

well, seems like no one is going to help me anyway

btw @Krzychups what is the battery you are using and what is the total power of the car, do you know how fast it goes, also what is the weight?

seems like IWD is the way to go 

i have all components but I have a drone stack ( flight controller and esc)

how do you program the flight controller?

i have tested it and the issue is:

when you are at zero throttle and arm,the motors spin very slowly

but even if you up the throttle just a tiny bit the motors continue speeding up, this can damage both the motors and esc

I did some research and found out that the esc speeds the motors up until the fc reports an increase in altitude(it is for drones anyway)

so my question is , how do you overcome this?

 

[Krzychups]

Hi! Here is a film:

On 10/22/2025 at 9:17 PM, gyenesvi said:

Can you show more details of your suspension arm design?

Here you go. They have holes for RC shocks. Unfortunately, I have noticed that holes for ball joints on 3D-printed wishbones wear out over time. At the moment, they are still working. 

Spoiler

 

On 10/23/2025 at 12:17 PM, keepbricking said:

i have all components but I have a drone stack ( flight controller and esc)

how do you program the flight controller?

i have tested it and the issue is:

when you are at zero throttle and arm,the motors spin very slowly

but even if you up the throttle just a tiny bit the motors continue speeding up, this can damage both the motors and esc

I did some research and found out that the esc speeds the motors up until the fc reports an increase in altitude(it is for drones anyway)

so my question is , how do you overcome this?

Well, I use the ESC without the FC. It's not needed for driving. I only use the FC to program the ESC. Please direct such questions to @janssnet; he has lots of experience with iWD cars. An iWD RC car is a good idea when it comes to you, I think.

Unfortunately, I've somehow broken my Geekservo...

On 10/22/2025 at 9:17 PM, gyenesvi said:

Nice car design, curious about the footage!

On 10/22/2025 at 8:57 PM, HorcikDesigns said:

And good job with the car!

Thanks!

Edited October 25 by Krzychups

[keepbricking]

19 hours ago, Krzychups said:

Well, I use the ESC without the FC. It's not needed for driving. I only use the FC to program the ESC. Please direct such questions to @janssnet; he has lots of experience with iWD cars. An iWD RC car is a good idea when it comes to you, I think.

I can't use the esc alone. it is a 4-in-1 ESC so it only works with the FC connected

btw @Krzychups what is the battery you are using and what is the total power of the car, do you know how fast it goes, also what is the weight?

[keepbricking]

 

@janssnetuses individual PWM ESCs, I think

[janssnet]

@keepbrickingHaven't read all your posts, what are you working on? I'm using both 4in1 ESCs and individual ESCs running BLHeli-s, BlueJay and/or AM32. What can i help you with?

 

[keepbricking]

@janssnetplease tell me how i can use just a 4-in-1 ESC with a receiver to make an IWD car,

my flight controller got burnt 

[janssnet]

Ok, to drive a (iWD) car using a drone ESC, you don't need a Flight Controller (FC). You 'just' need to connect the right wires. 

Take the throttle signal from your receiver (RX) and connect it to all (4) motor inputs on your ESC and connect GND from receiver to the ESC input.

Make sure the ESC is configured for Servo input (= PWM input, not DShot)  and you're ready to go!

 

What i mostly do is create a small print, using header pins (see attached image). Solder the RX throttle signal (white wire in this picture) to the 4 motor input pins in one row and solder the GND (black wire) to one of the last pin.

Solder the ESC motor inputs to the other row of pins (including GND).

With the jumpers OFF, you can configure the ESC (connect your FC * to the ESC). With the jumpers ON the ESC is connected to your receiver, ready to drive.

 

*) To drive the car you don't need the FC. However, to configure the ESC you do need the FC (so called 'pass through' mode). Connect your PC to the FC (USB), connect FC to ESC, start your configurator program, connect battery, and start configuring.

 

[NoEXIST]

It was kinda interesting to read some lastest "innovations" in inserting brushless into lego. However I can't really understand the point in using ESC's designed for flying vehicles in cars Maybe I'm just too "oldschool" in this term, but I would prefer one powerful enough Motor and ESC or in case of reusing lego motors - one powerful enough ESC to power all the motors that are used for propulsion. Hopefully someone will be able to explain the idea to me...

 

I also have done some attempts to jump into bigger brushed and brushless motors in my MOCs but not really tested at full load yet. Now I'm aiming to make a lego equivalent of Losi nascar cars as I was pretty close to it using buggy motors.

I also have been working on my RC system in one brick, however it seems like now you guys are not interested even in buggy motors anymore

[janssnet]

13 hours ago, NoEXIST said:

Hopefully someone will be able to explain the idea to me...

Not sure i can, can only speak for myself ... but it starts by adding a Buwizz or an SBrick to your models. Result is slightly underwhelming,  you want more. More speed, more power. So you start adding your own motors, adding your own RX/TX go get away from Bluetooth. Adding bearings, home-made gearing, 3D prints. Your own tyres, since the LEGO ones start ballooning  at your current speed. And it goes on and on, like an addiction . 

After building my LEGO in-wheel-drive buggy, i was so excited about the use of drone tech in a car, wanted to do an attempt to build an on-road rc car that was faster, quieter, less power consuming and cheaper than traditional rc cars.  

It took some effort and it took lots of time but with the help of others, it looks like we are on to something. Yes, an rc car based on tech for flying objects and it started with LEGO. Not sure were it's going to end .......

 

Please find the latest track test here, speed test coming up, car needs further tuning, but it looks very promising. We estimate 120+ km/h is doable! (using 4 drone motors €15 each and a 4in1 ESC €55). Has nothing to do with LEGO (anymore), sorry bout that.

https://drive.google.com/file/d/1Og2HeR4ggFpmgU-xFPQHCJT4zx4ERz0N/view?usp=sharing

NB The sound you hear is another (combustion) car on the track ;)

[gyenesvi]

13 hours ago, NoEXIST said:

It was kinda interesting to read some lastest "innovations" in inserting brushless into lego. However I can't really understand the point in using ESC's designed for flying vehicles in cars Maybe I'm just too "oldschool" in this term, but I would prefer one powerful enough Motor and ESC or in case of reusing lego motors - one powerful enough ESC to power all the motors that are used for propulsion. Hopefully someone will be able to explain the idea to me...

I guess it allows reaching ultimate speeds without worrying about melting parts. Maybe also it allows for ways of controlling speed of wheels separately to create under/overs-steer.

But I guess you are questioning the point of it because it removes the drivetrain, hence much of the realism modeling aspect. I tend to agree, I mean I like to build the drivetrains, but I guess you could say the in-wheel drive will also become kind of realistic of EVs.

13 hours ago, NoEXIST said:

I also have done some attempts to jump into bigger brushed and brushless motors in my MOCs but not really tested at full load yet. Now I'm aiming to make a lego equivalent of Losi nascar cars as I was pretty close to it using buggy motors.

That's a nice looking effort!

13 hours ago, NoEXIST said:

I also have been working on my RC system in one brick, however it seems like now you guys are not interested even in buggy motors anymore

Here's how I see it. I think using an RC system adds value to both brushed and brushless setups because of the good physical, configurable, precise control, plus the option to use proper servos. Also, it has the advantage of more powerful batteries compared to lego ones and even to Buwizz. Brushed RC electronics can be used with lego motors, buggy motors or Buwizz motors, so adding a brushed RC motor is not necessary. True that you could have a single more powerful motor, but then it is worth more to go brushless; it is a more efficient, more modern system with more active development I'd guess. Then it is possible to bring out the true power of modern RC systems, a single, small drive motor in better form factor than lego/buggy/buwizz motors.

While brushless motors have the potential to be overly powerful for lego parts and destroy everything, they also hide an opportunity: powerful smaller / lighter models.

By looking at many MOCs of the past and going to Buwizz competitions, I believe we have converged to a sweet spot of using max 4 Buwizz motors (powered by 2 Buwizz units), split into 2 pairs for front/rear axles. Even coupling 4 motors on a single axle has proven to be too much for the plastic (tried by different people on multiple occasions). Part of this is because building 4 buwizz motors and 2 buwizz units into a model already requires a fairly large scale and results in significant weight, and even when possible, it consumes a significant part of the space available / restricts drivetrain and suspension types. Also, the resulting speed already poses controllability problems, at least for off-roaders, where higher speeds can lead to more crashes and even just more stress on the parts due to bumps, which is again amplified by larger weight. So more precise control becomes more important.

Having the same amount of power at smaller/lighter models and more control over speed/steering could potentially push the limit further without melting/breaking the plastic. With powerful small brushless motors we have the potential to build models that are not just a big chunk of electronics, but also have space for more interesting/realistic drivetrain/suspension details and more aesthetic bodyworks as a few hundred grams of extra weight may not be an issue when a base is light enough.

My last build, the small Defender was an entirely different playing experience for me than my previous lego models, and it uses the smallest possible brushless motor I could find, is already too fast for my control capabilities and then I realized that my ESC wasn't even controlling it at full speed.. now imagine that in medium sized build where I can flesh out more complex suspension/drivetrain/bodywork..

So I guess what I'm saying is that if I already take the effort to use RC electronics, then restricting myself to poorly shaped buggy motors does not make too much sense if I have the option to use small powerful brushless motors too because now the limit with buggy motors is the power to size ratio. That's not to say I won't build with buwizz motors any more, but I guess I'll keep those for buwizz competitions.

[NoEXIST]

Thanks for the answers @janssnet @gyenesvi

As I can see and understand, we just did choose different path to put more power into our models. I myself try to make the actual transmission stronger by designing some specific parts that can give me some benefits of hobby grade RC cars design. For example I've made some modifications to lego differentials and new mounting system to eliminate backlashe where it shouldn't be. So now differential mounting doesn't rely on CV joints.

I also have found a photo of my brishless attempt, but i would like to put some of newer custom parts I designed to similar chassis and finally glue the tires to the rim itself (that was the biggest bottleneck)

19 hours ago, janssnet said:

Please find the latest track test here, speed test coming up, car needs further tuning, but it looks very promising. We estimate 120+ km/h is doable! (using 4 drone motors €15 each and a 4in1 ESC €55). Has nothing to do with LEGO (anymore), sorry bout that.

https://drive.google.com/file/d/1Og2HeR4ggFpmgU-xFPQHCJT4zx4ERz0N/view?usp=sharing

NB The sound you hear is another (combustion) car on the track ;)

That's great to see a track usage of self designed chassis! Unfortunately I didn't manage to find any in my locality, however I alse had my hands on something rc racing related. I was designing a retro gt12 inspired chassis for my college. I had only one opportunity to properly try it out, but I was really surprised how nicely it felt on carpet even with lego tires on.

I had to create a ball-differential for this car and now I'm really curious to try creating comething similar for a lego model

[keepbricking]

@janssnetI don't have the FC anymore 

I can't program it now

 

[vergogneless]

Always in pursuit of optimization for my small-scale builds, I’m currently testing a few new ideas.

First, I’ve been experimenting with a new way to mount the gear onto the motor shaft. I replaced the gear’s cross pin with a hole matching the motor shaft diameter (3.17 mm for the A2212). You have to press it in with a hammer, and once it’s in place, it won’t move a bit. I think this is the most reliable solution so far, and it also saves some space.

I’ve also bought a couple of new AM32 ESCs to test. Both are excellent, they’re “only” 30 A, but that’s more than enough for our small brushless motors. They’re just as compact as the usual ones people use here, but cost half as much.

And for a new build, which turned out to be the smallest vehicle I’ve ever made. I’ve been testing a different brushless motor I had mentioned earlier. It’s more compact than the A2212 but performs really well on lightweight models.

For the first time, I’m also using a servo other than the Geek Servo: the MG90S. Once adapted to the LEGO system, it’s even smaller than the smallest Geek Servo, yet it offers a torque of 2 kg compared to 0.5 kg is a bit faster and more precise, and all of its gears are metal.