[MOC] Trophic - trophy truck powered by brushless motor

[Krxlion]

Hi everyone!

I want to present you my proposal of a trophy truck. Main goal was to create a big model as capable in speed and climbing ability as it is possible. When main feature of the car was implemented I wanted to attach the body to it as simple as I could so I can reduce the weight effectively.

My model features:
- 1x 2838 4500KV Brushless waterproof motor for propulsion
- 1x Geek-Servo for steering
- Planetary wheel hubs
- Open 36-tooth differentials on both axles
- Brushless motor is connected to main drive shaft with 3:1 gear ratio
- Live rear axle
- Independed front suspension
- Reinforced steering joints
- Metal U-joints
- Closed bottom of the car
- Openable front hood

Mass: 1603g (1178g without the body)

Regarding brushless setup I used features(apart from what I mentioned above) those elements:
- DumboRC X6FG as transmitter and receiver
- Waterproof 35 ESC from SurpassHobby
- GensAce LiPo 1800mah 11.1V 45C
- White lithium grease from Lucas Oil(lubricating gears and each hole where axles turn)

Feel free to ask anything. I probably didn't cover everything about this model in this topic so it might be updated in the future. The model was run on the video with about 20-30% of full power, except few moments at the end, where it was approximatelly 60%. I might some day test it at full speed but let the model live for a while, haha. 

I want to thank those people which inspired me with their work to build my model: @Zerobricks @gyenesvi @Daniel-99

And here are some photos of the car and link to whole album - GALLERY

 

 

 

 

 

 

Edited March 21, 2023 by Krxlion

[TexasEngineer454]

Looks good!

Any more pictures of the front end steering/suspension?

Seems to hold together in the video really well. 

[FriedlS]

Great work! How heavy is the car?

Are these planetary hubs strong enough?

[Krxlion]

2 hours ago, TexasEngineer454 said:

Looks good!

Any more pictures of the front end steering/suspension?

Seems to hold together in the video really well. 

I have added more photos into the gallery, please take a look. :) I reinforced steering joints so they will not pop out during high speed on bumpy road - there is 61184 brick inside pin hole, where ball pin is insterted. Apart from that, most of front axle comes from one of @gyenesvi MOCs (he has available instructions on rebrickable), I adapted it to my MOC, reinforced steering mechanism and found a way to insert a geek-servo instead of PU L motor

13 minutes ago, FriedlS said:

Great work! How heavy is the car?

Are these planetary hubs strong enough?

No issues at all with planetary hubs, they hold very well! Although, I must mention that previous version of the MOC had 52730+77590 in the rear part of driveshaft and 52730 broke down(those small plastic grooves where you insert 77590 brick), so I ended up with switching to 92911+92910 setup and inside is metal U-joint. Model weights 1603g (1178g without the body).

[Daniel-99]

Hey! This is an interesting model indeed! Actually, it has several things is common with @Zerobricks universal 4x4 off-roader:

Planetary hubs will last for long here, though they will fall into dust after extensive driving. In my builds I use Chinese version which can be disassembled and lubricated quite easily. 

Do you plan any future upgrades of your truck? I think it is worth upgrading the transmission with custom parts: metal bearings increase the mechanical level of a car dramatically from my opinion. Also if you are more aiming for speed and not for 4x4 off-roader, you might also enjoy wheel hubs with metal bearings (planetary hubs reduces the speed too much, and have a lot of unnecessarily friction). But this are only my thoughts, so keep up and have fun with your nice truck!

 

 

[Krxlion]

17 minutes ago, Daniel-99 said:

Hey! This is an interesting model indeed! Actually, it has several things is common with @Zerobricks universal 4x4 off-roader:

Planetary hubs will last for long here, though they will fall into dust after extensive driving. In my builds I use Chinese version which can be disassembled and lubricated quite easily. 

Do you plan any future upgrades of your truck? I think it is worth upgrading the transmission with custom parts: metal bearings increase the mechanical level of a car dramatically from my opinion. Also if you are more aiming for speed and not for 4x4 off-roader, you might also enjoy wheel hubs with metal bearings (planetary hubs reduces the speed too much, and have a lot of unnecessarily friction). But this are only my thoughts, so keep up and have fun with your nice truck!

 

 

Yup Daniel, cover of all gears that are running in the car is necesarry, due that the bottom of the car is covered in all kind of plates and liftarms. I have runned model 3 times and didn't yet need to strip it apart and clean it to get dirt out of, which is great!

Are those planetary hubs that you are talking are available on chinese website(If you know what I mean)? :D I currently run original Lego ones but If they will break I will be more than upset, haha.

I would love to upgrade the model, I am more of a person that upgrades the model, instead of stripping it and going to another. Currently I have few issues:
- Turn radius is not so great
- Bad fit of BL motor in the car(the motor is slightly bigger than three lego studs - 28mm diameter, where ideally it should be 24mm)
- Modify body - I cannot climb steep obstacles, because of the size of the body structure

I have no knowledge regarding metal bearings (no bearings I know will fit lego liftarms, you will need to heavilly modify it or buy whole liftarm with bearing). Regarding moving from planetary hubs to metal ones, I believe that soon after the change of original plastic hubs I will start breaking 52730+52731 parts in the front axle. I might though be mistaken because I've never used previously metal hubs.

All in all, I was afraid of using 2838 4500KV motor in the setup but I believe with some pruedence and starting reduction(for example 3:1) you may run it in your models.

[TexasEngineer454]

3 minutes ago, Krxlion said:

- Modify body - I cannot climb steep obstacles, because of the size of the body structure
 

Do you mean the car doesn't have enough torque to go up steep inclines? Or it doesn't have enough clearance to go over a steep crest? 

 

I am having similar issues with my RC MOC and am curious as to how you plan on working around this problem? 

[Krxlion]

1 minute ago, TexasEngineer454 said:

Do you mean the car doesn't have enough torque to go up steep inclines? Or it doesn't have enough clearance to go over a steep crest? 

 

I am having similar issues with my RC MOC and am curious as to how you plan on working around this problem? 

The second thing. Currently I have mounting points of my body slightly in front of a car which decrease full potential of climbility of the car.

[TexasEngineer454]

Would more ground clearance fix this? 

The solid rear axle would limit the amount of height you could get from this build. 

Best solution maybe to convert to AWD.

[Krxlion]

1 hour ago, TexasEngineer454 said:

Would more ground clearance fix this? 

The solid rear axle would limit the amount of height you could get from this build. 

Best solution maybe to convert to AWD.

The problem is not with ground clearance but with body starting too much in front of the front wheels(I do not know how to put in words differently), my MOC have 107mm diameter wheels and it is AWD. I do not understand the part, where you say that rear axle would limit the amount of height. Can you be more precise?

[2GodBDGlory]

4 minutes ago, Krxlion said:

The problem is not with ground clearance but with body starting too much in front of the front wheels(I do not know how to put in words differently), 

Probably approach angle would be the term for that?

[Daniel-99]

6 hours ago, 2GodBDGlory said:

Probably approach angle would be the term for that?

I would say differently. It is possible to increase the ground clearance under the front axle by lifting the suspension (since it is independent). While the ground clearance under rear solid axle is fixed and require either bigger wheels or portal hubs to increase the clearance. 

[Daniel-99]

8 hours ago, Krxlion said:

Yup Daniel, cover of all gears that are running in the car is necesarry, due that the bottom of the car is covered in all kind of plates and liftarms. I have runned model 3 times and didn't yet need to strip it apart and clean it to get dirt out of, which is great!

Yep, this is always good for RC models if you cover the bottom. Though it is impossible to 100% protect the transmission from the mud and dust (as it is done in real cars). Even with covered bottom, you will find some dirt and water inside your car coming from the wheels: mud from rear wheels will cover the car from the very back to the front end of rear wheels, while the front wheels (since you have AWD) will cover the whole cockpit. Thai is why I made realistic mudguards from a plastic bottle for my latest project (also my Falcon has a mud-protection in the front, to save the electronics from the flow of stones coming under the front wheels). Finally, even with all possible protections, regular dust will be a problem forever. I drove my cars on a dusty roads last summer and had to wash the whole car after each driving session. Such kind of dust is deadly for the plastic transmission.

8 hours ago, Krxlion said:

Are those planetary hubs that you are talking are available on chinese website(If you know what I mean)? 

Yes they are, it is easy to find them and the quality is good. Also they are cheaper than the original parts. So they will serve well as plastic parts which need a periodic  replacement.

8 hours ago, Krxlion said:

Regarding moving from planetary hubs to metal ones, I believe that soon after the change of original plastic hubs I will start breaking 52730+52731 parts in the front axle. I might though be mistaken because I've never used previously metal hubs.
All in all, I was afraid of using 2838 4500KV motor in the setup but I believe with some pruedence and starting reduction(for example 3:1) you may run it in your models.

Indeed planetary hubs relieve the transmission, which will not happen with normal hubs. Also you have both big wheels and powerful motor, so I can not tell you if I it is possible to build a transmission strong enough to transfer all power from motor to wheels without planetary reduction. You will have to test it by yourself (though it is quite risky).

What is the max speed of your trophy truck? I tried to calculate it from the video and it seems to be about 10-12 km/h. Such speeds I achieve with 1200 kv brushless motor and transmission with metal bearings. 

[Krxlion]

10 hours ago, 2GodBDGlory said:

Probably approach angle would be the term for that?

Yes, exactly the word I was looking for. :) I put few more photos of the front from side view, so If you want you can see the approach angle.

3 hours ago, Daniel-99 said:

I would say differently. It is possible to increase the ground clearance under the front axle by lifting the suspension (since it is independent). While the ground clearance under rear solid axle is fixed and require either bigger wheels or portal hubs to increase the clearance. 

Yup, it could be done the way you say, Daniel. But after all I believe that currently I will focus on fixing mounting points of front section of the body and modify slightly body itself.

3 hours ago, Daniel-99 said:

Yep, this is always good for RC models if you cover the bottom. Though it is impossible to 100% protect the transmission from the mud and dust (as it is done in real cars). Even with covered bottom, you will find some dirt and water inside your car coming from the wheels: mud from rear wheels will cover the car from the very back to the front end of rear wheels, while the front wheels (since you have AWD) will cover the whole cockpit. Thai is why I made realistic mudguards from a plastic bottle for my latest project (also my Falcon has a mud-protection in the front, to save the electronics from the flow of stones coming under the front wheels). Finally, even with all possible protections, regular dust will be a problem forever. I drove my cars on a dusty roads last summer and had to wash the whole car after each driving session. Such kind of dust is deadly for the plastic transmission.

Yes they are, it is easy to find them and the quality is good. Also they are cheaper than the original parts. So they will serve well as plastic parts which need a periodic  replacement.

Indeed planetary hubs relieve the transmission, which will not happen with normal hubs. Also you have both big wheels and powerful motor, so I can not tell you if I it is possible to build a transmission strong enough to transfer all power from motor to wheels without planetary reduction. You will have to test it by yourself (though it is quite risky).

What is the max speed of your trophy truck? I tried to calculate it from the video and it seems to be about 10-12 km/h. Such speeds I achieve with 1200 kv brushless motor and transmission with metal bearings. 

Great explanation, I don't want though to use this much of non-brick things in my models(custom hubs and liftarms with bearings are still ok, but the plastic cover from a bottle is not something that I would use in my model ;)). The main goal was to simply power the car using the brushless setup and rest should be solved with technic bricks(although I know they have their limits).

I might test different solutions like using hubs without gear reduction or portal hubs, we will see in the future. :)

The top speed is still unknown, but I would like to check it for my own curiosity and for that I might do a setup like this:

- Find straight road without much traffic
- Place camera where it can cover wide angle of the road
- Place two objects(for example bottles) in 10 meters separation
- Run the model in full speed between those two objects
- Calculate estimated speed (record with 60fps for as much frames as I can, count the frames between entry and ending points - those two placed objects. Finally, do the math :D)

[TexasEngineer454]

4 hours ago, Krxlion said:

Yes, exactly the word I was looking for. :) I put few more photos of the front from side view, so If you want you can see the approach angle.

Yup, it could be done the way you say, Daniel. But after all I believe that currently I will focus on fixing mounting points of front section of the body and modify slightly body itself.

I looked through your album and I see the issue you are talking about. The body mounts stick out past the front axle far enough to cause a problem when crawling over obstacles. Would it be possible to fix these mounts? Or else remove them completely. 

It looks like you have the 107x44 tires. I wonder if going to a taller tire would help fix part of the issue. 

 

[Johnny1360]

@Krxlion I love what you are doing and can appreciate that you are looking to stick with Technic parts as much as possible, just not my cup of tea, keep up the great work and keep us updated as you make changes. One thing though will you please turn the directional tires, with self cleaning tread around the other way, before my brain explodes, lol.

[Maaboo the Witch]

On 3/21/2023 at 5:36 PM, Johnny1360 said:

@Krxlion I love what you are doing and can appreciate that you are looking to stick with Technic parts as much as possible, just not my cup of tea, keep up the great work and keep us updated as you make changes. One thing though will you please turn the directional tires, with self cleaning tread around the other way, before my brain explodes, lol.

These tyres are from the CADA monster truck, funnily enough. They look more industrial than TLG's version. I'd actually like a set; they'd look great on the Volvo ZEUX.

[Krxlion]

After some minor MOC tweaking I have prepared myself for measuring the top speed of TROPHIC. I found a straight line, placed two small glass bottles in exact 10 meters separation and runned model through them several times. I then calculated frames in editing program and came with the results:

 

On 3/21/2023 at 5:04 PM, TexasEngineer454 said:

I looked through your album and I see the issue you are talking about. The body mounts stick out past the front axle far enough to cause a problem when crawling over obstacles. Would it be possible to fix these mounts? Or else remove them completely. 

It looks like you have the 107x44 tires. I wonder if going to a taller tire would help fix part of the issue. 

 

The body mount is now fixed and the model can climb steep objects such as big curbs. Regarding second part of your answer, I do not believe there are bigger Lego Technic wheels than 107x44 that will suite this kind of MOC.

On 3/21/2023 at 6:36 PM, Johnny1360 said:

@Krxlion I love what you are doing and can appreciate that you are looking to stick with Technic parts as much as possible, just not my cup of tea, keep up the great work and keep us updated as you make changes. One thing though will you please turn the directional tires, with self cleaning tread around the other way, before my brain explodes, lol.

Fixed! 

On 3/22/2023 at 6:58 PM, Maaboo35 said:

These tyres are from the CADA monster truck, funnily enough. They look more industrial than TLG's version. I'd actually like a set; they'd look great on the Volvo ZEUX.

Correct! I've also the Lego version of those wheels but somehow I like the grey option on this model. If you would like to get them cheap, you may buy CADA C61008W set. ;) 

 

[Daniel-99]

Hey! 

Good tests were made! And I am impressed with a max speed of your truck even with planetary hubs the motor made the car a fast beast! 

I wonder if your truck feels stable on a hight speed? I suppose that off-road tires and the lack of positive caster affect on the control. Does your receiver has an SVC system with gyro?

[Krxlion]

18 minutes ago, Daniel-99 said:

Hey! 

Good tests were made! And I am impressed with a max speed of your truck even with planetary hubs the motor made the car a fast beast! 

I wonder if your truck feels stable on a hight speed? I suppose that off-road tires and the lack of positive caster affect on the control. Does your receiver has an SVC system with gyro?

Hi there, Daniel!

Yes! The receiver has gyro function and it has been turned on, but it has not been securly attached into the body(it holds by Lego rubber band) and it slightly wobles when I speed I believe. During runs the gyro function was on, but set like to 20% of max value and I believe it didn't had much impact into steering performance If any. I ran into several problems in the meantime:
- Planetary hubs (and I believe all lego hubs) have slight issue with wobbling.
- Car do not run straight in high speed. I could try using positive-caster on the front (I built car with this function before) but I am worrying about implementing another set of 92911+92910 bricks(or other option) to change angle of driveshaft in the front.

I will probably first try to securly attach receiver to help me stabilise the car during speeding. Then If that will not work, I will probably try to built much less wobbly hubs out of bricks(I've seen few idead on the Internet). Lastly I can try custom hubs, etc. but this will be final option, though it is curious for me how they perform. :)

[TexasEngineer454]

That maneuvering at 1:32 in the video was great!

 

Great job on the build!

[LEGO Train 12 Volts]

Great model, from the pictures this car doesn't seem too heavy which is great for speed; the generous suspension makes the car extremely agile!
All well proportioned!

[janssnet]

On 3/25/2023 at 12:57 PM, Krxlion said:

I will probably first try to securly attach receiver to help me stabilise the car during speeding. Then If that will not work, I will probably try to built much less wobbly hubs out of bricks

Great stuff Krxlion!

My advice: do both! Fix the gyro-stability and (by all means) implement positive castor. The latter is a serious revision, but is very rewarding. A slight angle (like 8 degrees) can already make a huge difference in straight line stability.