Brushless motors in the lego world - general topic

[vergogneless]

On 1/23/2025 at 12:05 PM, Aurorasaurus said:

As I mentioned a little bit ago, AWD is where I thought to take my brushless adventure next. So, here it is!

Wheel hubs: I'm using custom wheel hubs, 3d printed from PLA and using a 15x21x4mm bearing. In the rear I have a simple design I'm sure I showed earlier here, with 2 degrees of negative camber. These ones have the bearings held in with glue. In the front I tried something else; the wheel hubs have no glue. The bearing is put inside the hub while it is printing, then the print continues and traps the bearing in. In theory, now the weak link is the 3d printed plastic. If/when the wheel hubs break, you can simply reprint them. Because there is no glue, the bearing will be easy to re-use. The front hubs have a high caster angle and 2 degrees of camber. STL files for the hubs: LEFT, RIGHT.

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Drivetrain: I'm using 2x metal differentials from ZENE. They make a funny noise but work flawlessly so far. Every part in the drivetrain that could melt has been replaced by parts with bearings in them. I'm using a 1400kv 10t a2212 brushless motor from aliexpress. I gear it down 12:36/1:3 for more torque, and then 16:16 to lower the drive axle for the front, just because of how I made the model. The metal differentials from ZENE apparently have a 1:1.6 ratio, so the overall ratio from the motor is around 1:5. This proves very effective at keeping the speed high while also providing enough torque to easily run on grass.

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For suspension, I have independent front suspension, and a rear 4 link live axle. The rear axle was very heavy, and very robust. It has angled drive elements in order to get more ground clearance in the rear. Here you can also see how I achieved caster angle at the front without tilting the suspension arms.

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Like all my models, this has problems. For this one, the front ground clearance simply isn't enough, and the springs come apart when you do jumps or whatever. I broke a few parts, but nothing major this time. To get the half red axle out of the metal diff, I used a small drill bit and then a screw, and then some pliers.

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Electronics: Hobbywing Quicrun 10bl60 ESC, Giantpower 1500mah 3s 60c LIPO, 1400kv 10t a2212 brushless motor, dumborc x6fg receiver and dumborc x6 transmitter, geekservo 360 2kg, generic battery buzzer from the RC store.

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More photos

Feel free to ask any questions, but please bear in mind I have already disassembled this model.

 

Bravo for all your hard work! I'm glad to see that the 4x4 works well with brushless motors and for bashing, especially thanks to Zene's differentials!

I’m planning to build a 4x4 model too, but more road-oriented, using Zene’s wheel hubs (and therefore conventional RC wheels), his differentials of course, and his brushless motor.

 

Are your wheel hubs holding up after intense use? Even though they have ball bearings, there’s still a lot of plastic contact, and your model seems to take on heavy acceleration and top speeds. From my perspective, with so much friction on the plastic, you must be noticing and feeling increasing play over time? What I mean is, the plastic inevitably ends up melting or, at best, crumbling away...

 

That’s my main concern when testing Zene’s wheel hubs, as they’re plastic and already have some play out of the box. In my humble opinion, they won’t last long. I think the metal wheel hubs from MTP are the only truly viable long-term alternative when aiming for acceleration and top speed. 

 

For your suspension system, beyond improving ground clearance, have you considered switching to oil-filled shocks like @Krzychups did earlier on this page?
I think this is the last essential step to move away from Lego spring shocks, which are completely banned from conventional RC builds except for children’s toys.

 

I plan to take that step for my 4x4 model and even switch permanently for all my models regardless of scale. I know we’re drifting further from Lego, but it’s the logical next step, given how far we’ve already come!

I just need to motivate myself— I have almost everything I need, but my work drains a lot of my physical and mental energy. Plus, where I live, the weather is cold and rainy 90% of the time, which doesn’t help with testing or making videos. I have three models already built that I need to present on the forum, but they’re peacefully sitting on my shelves for now.

In any case, I’m looking forward to seeing more of your experiments!

[Aurorasaurus]

15 minutes ago, vergogneless said:

 

Bravo for all your hard work! I'm glad to see that the 4x4 works well with brushless motors and for bashing, especially thanks to Zene's differentials!

I’m planning to build a 4x4 model too, but more road-oriented, using Zene’s wheel hubs (and therefore conventional RC wheels), his differentials of course, and his brushless motor.

 

Are your wheel hubs holding up after intense use? Even though they have ball bearings, there’s still a lot of plastic contact, and your model seems to take on heavy acceleration and top speeds. From my perspective, with so much friction on the plastic, you must be noticing and feeling increasing play over time? What I mean is, the plastic inevitably ends up melting or, at best, crumbling away...

 

That’s my main concern when testing Zene’s wheel hubs, as they’re plastic and already have some play out of the box. In my humble opinion, they won’t last long. I think the metal wheel hubs from MTP are the only truly viable long-term alternative when aiming for acceleration and top speed. 

 

For your suspension system, beyond improving ground clearance, have you considered switching to oil-filled shocks like @Krzychups did earlier on this page?
I think this is the last essential step to move away from Lego spring shocks, which are completely banned from conventional RC builds except for children’s toys.

 

I plan to take that step for my 4x4 model and even switch permanently for all my models regardless of scale. I know we’re drifting further from Lego, but it’s the logical next step, given how far we’ve already come!

I just need to motivate myself— I have almost everything I need, but my work drains a lot of my physical and mental energy. Plus, where I live, the weather is cold and rainy 90% of the time, which doesn’t help with testing or making videos. I have three models already built that I need to present on the forum, but they’re peacefully sitting on my shelves for now.

In any case, I’m looking forward to seeing more of your experiments!

Firstly, thanks for the kind words!

My hubs havent had any issues yet, but I dont personally feel I thrashed this model very hard. The slack in the hubs is exactly the same as when I made them. There is a little bit, because the design is not perfect. About the acceleration, I actually have it set below the stock setting in my ESC because the original setting was just insane.

I hadn't thought much about RC shocks, in theory the only problem is mounting them since they need to use screws instead of pins. I don't like the idea of screwing into the lego,  dont want the screw to flop around in the pinhole either. If there were some shocks that took a screw that was <4.8mm in diameter but >4.6mm in diameter then I'd be happy to try them. Or maybe I could 3d print a little washer to not have the screw flop in the pinhole. Next time I need to go to the RC store I may see what they have, thanks for the idea.

I'll be curious to see how you implement RC springs in your model. How big is it? If my memory serves me well, all your past models were very little, and RC shocks are large, right?

Again, thank you for the encouragement and praise, and best wishes to you for your models, and better weather.

[Ryokeen]

5 hours ago, Aurorasaurus said:

I don't like the idea of screwing into the lego

Put a pin without friction(the ones with round holes in them) or a 1 1/4 pin (pin with stud) in a liftarm. Most 1/10 - 1/8 RC shocks are mounted with m3 screws and they fit nicely without slack through said pin parts. Also the pins will prevent any damage to the liftarm and also stabalize a bit. I used that in every of my RC brick cars and never had a slopy shock or any damage done to the mounting point, even at longer jumps

[Variteck]

Thanks HorcikDesigns and Aurorasaurus. In the end, after extracting the Omega clip, I solved it thanks to my son's hammer ;)

[Aurorasaurus]

7 hours ago, Ryokeen said:

Put a pin without friction(the ones with round holes in them) or a 1 1/4 pin (pin with stud) in a liftarm. Most 1/10 - 1/8 RC shocks are mounted with m3 screws and they fit nicely without slack through said pin parts. Also the pins will prevent any damage to the liftarm and also stabalize a bit. I used that in every of my RC brick cars and never had a slopy shock or any damage done to the mounting point, even at longer jumps

Great idea, thank you very much!

2 hours ago, Variteck said:

Thanks HorcikDesigns and Aurorasaurus. In the end, after extracting the Omega clip, I solved it thanks to my son's hammer ;)

My dad used to say: everything is a nail if you have a hammer! I'm glad you found a solution, and hope the rest of your brushless journey goes smoothly too.

[Krzychups]

Hi everyone!

I'd like to ask if it's worth buying planetary wheel hubs (from Aliexpress because they're cheap)? I've been focused on my rc crawler, so far I've redesigned it. I'd like to use them with rc rims, but it might be problematic. I'm using high reduction after the motor which is: planetary gearbox reduction (5,2:1), 36:12, 36:12, differential ratio (28:12 or 22:14).

Secondly, should I buy the PF XL motor and use a brushless motor? Not the Lego one, but the one from Aliexpress. The A2212 motor or the 2838 one, or smaller like 2445 or 2435? It has a high reduction (36:1). Would the motor destroy it? What is your experience?

[Aurorasaurus]

3 minutes ago, Krzychups said:

Hi everyone!

I'd like to ask if it's worth buying planetary wheel hubs (from Aliexpress because they're cheap)? I've been focused on my rc crawler, so far I've redesigned it. I'd like to use them with rc rims, but it might be problematic. I'm using high reduction after the motor which is: planetary gearbox reduction (5,2:1), 36:12, 36:12, differential ratio (28:12 or 22:14).

Secondly, should I buy the PF XL motor and use a brushless motor? Not the Lego one, but the one from Aliexpress. The A2212 motor or the 2838 one, or smaller like 2445 or 2435? It has a high reduction (36:1). Would the motor destroy it? What is your experience?

I used an a2212 with xl motor reduction, I've only tried it in a model once (with a very poor drivetrain design) and broke an axle on the first bump because of the sheer mad torque from the motor. If you can drive a little carefully and manage a proper drivetrain (unlike me ) I think it will be okay. Just spec 1400kv or slightly greater so you get a decent output rpm. I think you can find all the files I used a page or 2 back, maybe that will help you.

In regards to planetary hubs, I've no experience with aliexpress ones, but I would expect them to be fine. Since you're using brushless power, I would stick to fake ones, theres no point destroying more expensive things for no reason.

[2GodBDGlory]

2 hours ago, Krzychups said:

Hi everyone!

I'd like to ask if it's worth buying planetary wheel hubs (from Aliexpress because they're cheap)? I've been focused on my rc crawler, so far I've redesigned it. I'd like to use them with rc rims, but it might be problematic. I'm using high reduction after the motor which is: planetary gearbox reduction (5,2:1), 36:12, 36:12, differential ratio (28:12 or 22:14).

Secondly, should I buy the PF XL motor and use a brushless motor? Not the Lego one, but the one from Aliexpress. The A2212 motor or the 2838 one, or smaller like 2445 or 2435? It has a high reduction (36:1). Would the motor destroy it? What is your experience?

I've had good experience with wheel hubs from Ali. The one thing you need to be aware of is that the ones I got weren't lubricated at all, but they also weren't glued together at all, so it was easy to lubricate them myself and superglue it shut! Since then I don't think there's any issues to speak of, and they're way cheaper!

[Variteck]

My truck asking me when it will be able to speed on the ground...

I am testing 2 different rear axles, both with differential this time, reduction 1/18 and 1/14 approximately (this one with Didumos wheel housing). In the first case the differential is too weak, the central bevel gear wears out and the teeth jump,

in the other version I obtained the fusion of an axle with a beam.

Still working on it...

[Aurorasaurus]

@Variteck Nice to see some progress, have you tested these outside yet?

On another note, does anyone have a solution for getting a secondary motor, for a winch/other motorized function working with a brushless setup? I can attach gray geekservos to my receiver but they still act as servos not motors, which I guess is to be expected.

[msk6003]

29 minutes ago, Aurorasaurus said:

@Variteck Nice to see some progress, have you tested these outside yet?

On another note, does anyone have a solution for getting a secondary motor, for a winch/other motorized function working with a brushless setup? I can attach gray geekservos to my receiver but they still act as servos not motors, which I guess is to be expected.

How about put extra PF batterybox and use PF switch with geekservo?

[Aurorasaurus]

9 minutes ago, msk6003 said:

How about put extra PF batterybox and use PF switch with geekservo?

I considered that... its a lot of extra weight and unneeded complexity, if there exists a better solution I would prefer that.

[Variteck]

2 hours ago, Aurorasaurus said:

@Variteck Nice to see some progress, have you tested these outside yet?

Of course: all the damage reported is the result of a few minutes of use on the road. The photos I have inserted refer to the untouched rear axles, before the road test. Here instead is a photo relating to the damage to the central wheel of the differential. You will notice the 12t metal wheel of the MTP, the original Lego one had disintegrated immediately.

 

[FriedlS]

7 hours ago, Aurorasaurus said:

@Variteck Nice to see some progress, have you tested these outside yet?

On another note, does anyone have a solution for getting a secondary motor, for a winch/other motorized function working with a brushless setup? I can attach gray geekservos to my receiver but they still act as servos not motors, which I guess is to be expected.

There are similar Motors like the geek servo but with different colors e.g. green or red. They spin as long as you want. Also forward and backwards.

 

Edited February 7 by FriedlS

[Ryokeen]

9 hours ago, Aurorasaurus said:

@Variteck Nice to see some progress, have you tested these outside yet?

On another note, does anyone have a solution for getting a secondary motor, for a winch/other motorized function working with a brushless setup? I can attach gray geekservos to my receiver but they still act as servos not motors, which I guess is to be expected.

If you have more than 2 channels on your receiver(preferred a 3rd channel with something like a 3 way switch) you can just plug in another small esc into that channel. That 2nd esc needs to be powered aswell, but make sure the 3 pin connector to your receiver only uses signal and ground(else you fry your electronos, as only one esc should provide the receiver and servos with power) And for motors then you can use the red geekservos or pf motors(pf connector adapter needed).

In short, for every dc motor/brushless motor you need an esc to power/controll it. But only ever have one esc provide power to the receiver and servos

Edited February 7 by Ryokeen

[FriedlS]

23 minutes ago, Ryokeen said:

If you have more than 2 channels on your receiver(preferred a 3rd channel with something like a 3 way switch) you can just plug in another small esc into that channel. That 2nd esc needs to be powered aswell, but make sure the 3 pin connector to your receiver only uses signal and ground(else you fry your electronos, as only one esc should provide the receiver and servos with power) And for motors then you can use the red geekservos or pf motors(pf connector adapter needed).

In short, for every dc motor/brushless motor you need an esc to power/controll it. But only ever have one esc provide power to the receiver and servos

The red and green geek motors have the esc already inside and the same dimension as the grey geek servo 😊

[Ryokeen]

1 hour ago, FriedlS said:

The red and green geek motors have the esc already inside and the same dimension as the grey geek servo 😊

Not the red ones i have, those have just 2 wires, positive and ground, so an esc is needed to produce a at least a pwm signal(or in that matter regulate voltage and polarity).

[FriedlS]

12 hours ago, Ryokeen said:

Not the red ones i have, those have just 2 wires, positive and ground, so an esc is needed to produce a at least a pwm signal(or in that matter regulate voltage and polarity).

Ah ok, thank you for the information 😀 I thought that the red one is like the green one:

green motor update

 

Edited February 8 by FriedlS
Link updated

[Aurorasaurus]

6 minutes ago, FriedlS said:

Ah ok, thank you for the information 😀 I thought that the red one is like the green one:

Green motor

 

Your video appears to be private.

Why not put it on YT and unlist it? Personal preference?

[FriedlS]

9 minutes ago, Aurorasaurus said:

Your video appears to be private.

Why not put it on YT and unlist it? Personal preference?

Update done

[Aurorasaurus]

3 hours ago, FriedlS said:

Update done

Awesome. It looks like it turns fast enough for me. How have you found the mounting points on it? They look.. not well thought out.

[gyenesvi]

On 2/7/2025 at 9:08 AM, Aurorasaurus said:

On another note, does anyone have a solution for getting a secondary motor, for a winch/other motorized function working with a brushless setup? I can attach gray geekservos to my receiver but they still act as servos not motors, which I guess is to be expected.

As noted above already, there are other GeekServos you could use, but the colors do matter. They exist in the same form factor as the most popular (grey) ones we all know.

- the grey ones are the classic positional servos

- the red and blue ones are simple DC motors (2 wires, so they need ESC), running at 180 and 90 RPM respectively

- the green ones are continuous rotation speed servos, they should work off the receiver without the need for an ESC

Also, GeekServos exist in the above linked weird form factor, but I think those were originally designed for studded building, so not that practical.

So I'd try the green one as the simplest thing, I always wondered about it's speed / power, whether they are strong enough for a winch for example..

 

[Krzychups]

@2GodBDGlory, @Aurorasaurus thank you for your replies, I've ordered 4 of them. Initially I have an idea how to mount 12 mm hex rims. I have rims which consist of 3 parts I screw together (also there's no need to glue tires, because by screwing these parts tires are locked), so I'll print four of them with mounting holes for the wheel hubs. In this way, the offset of the wheel from the pivot point won't be so big.

Edited February 10 by Krzychups

[Aurorasaurus]

I found a video today showing many custom parts, intended for use in brushless models. I thought I should share it, it seemed to be a good idea bank.

As for my own wheel hubs I showed last time, I now have given them plenty of abuse and nothing on them broke, and the amount of play is the same. Now the challenge is to find the optimal mounting points for the steering links and upper/lower arms. Any suggestions?

[Krzychups]

56 minutes ago, Aurorasaurus said:

As for my own wheel hubs I showed last time, I now have given them plenty of abuse and nothing on them broke, and the amount of play is the same. Now the challenge is to find the optimal mounting points for the steering links and upper/lower arms. Any suggestions?

Good to hear. Look at my designs or at @Daniel-99 bricksafe. He has custom wheel hubs. I've modelled them on the wheel hubs he has.

Why I can't hide text and images?