Simple Off-Roader + Instructions

[Zerobricks]

Many people have been asking me for a simple, easy-to build and most importantly cheap Off-Roader.

When I started this project, I've set myself the following guidelines:

• Use a single BuWizz 3.0 and "only" 2 BuWIzz drive motors
• Implement a 2 speed gearbox
• Maximize the ground clearance by using a pendular axle (this way the independent suspension doesn't have to loose ground clearance when going over obstacles)
• The model has to be built from under 500 parts
• All the parts have to be standard and in current production
• Keep the number of different parts as low as possible
• Use color coding to simplify the building process
• Design the model so that it can easily be modified by other builders
• Create proper building instructions

And this is what I came up with in the end:

I managed to successfully realize the all the planned functionality, features and more:

• All wheel drive
• 2 speed gearbox
• Pendular front axle
• Independent suspension on all wheels
• Openable doors for easy acces to the charging port
• Interior with seats and a steering wheel

The dimensions and specs are as following:

• Built out of  ~460 parts
• 27 x 20 x 13 cm
• ~ 850 grams
• Top speed of 7 km/h

As usual there's a video showcasing the model in more detail:

 

But just building the model and recording the video was only half the story. I also taught myself how to create the building instructions using the Studio which can be found here:

https://bricksafe.com/pages/Zblj/simple-off-roader

Since these are my first such instructions, they may not be ideal...

So in a case of any issues, confustion, or such I also uploaded the .IO and .LXF files which can be found in the corresponding Bricksafe folder:

https://bricksafe.com/pages/Zblj/simple-off-roader

All in all this was a great learning experience, I'm always happy to learn a new skill and being able to create my own instructions sure is a good skill to have as a LEGO builder.

To conclude; using this as a base, I wonder what kind of tweaks, improvements and crazy mods other builders will come up with!

Edited November 26, 2023 by Zerobricks

[Ryokeen]

Nice one, low part count and fully functional, that's a massive challenge. Ven with a small steering wheel, i rly like it not only as a base but as a small working offroad example. Good work there.
So you made the whole front section a pendular axle with additional individual wishbone suspension ?

[gyenesvi]

That's a really sweet one! I think the 1 Buwizz + 2 Buwizz motors setup is a great one, pretty good power for medium sized models at an affordable price. And I'm glad that you made this layout as it's just something I want to experiment with, so far I have not used the fast outputs coupled and channeled into a gearbox, good to know that the plastic can still withstand that. Did you notice any wear on the gearbox parts? I have also been wondering whether it would need red differentials at this speed or still has enough torque for climbing? Any tests you did with that?

On the front suspension there are some 6L links attached to the steering motor. What are those for? Stabilizing the front axle agains tilting backwards?

[Zerobricks]

2 hours ago, Ryokeen said:

So you made the whole front section a pendular axle with additional individual wishbone suspension ?

Yes, the whole front axle tilts and also has independent suspension.

1 hour ago, gyenesvi said:

Did you notice any wear on the gearbox parts? I have also been wondering whether it would need red differentials at this speed or still has enough torque for climbing? Any tests you did with that?

On the front suspension there are some 6L links attached to the steering motor. What are those for? Stabilizing the front axle agains tilting backwards?

No wear on the gerabox parts so far, but haven't driven it that much. Plenty of torque as it is already, so I see no need for addiitonal gearing. Yes, the 6L links keep the front axle from bending, without them it's much more loose.

Thank you both for the praise.

[Celeri]

Excellent tiny off-road monster, a big thanks for sharing it!

I was about to ask you how you implemented the remote-controlled gearbox, but then I looked into your instructions and found it (for those who wonder, the gearbox itself is built at the beginning, but the ratio-changing mechanism is completed on steps 27&28), and I find it really clever!

If I had the required BuWizz hardware, I would definitely build it

[Krxlion]

Great job, Zerobricks! I am gonna definitely try out this build one day. The potential of modification is very wide like you explained in the video.

[Daniel-99]

A good car for a wide technic community! Thanks for sharing!

[Doua]

Thanks for this, it looks awesome and very sturdy! I will definitely build this in the future; need to get my hands on a second hand Zetros since it seems to have most of the rarer parts needed (hubs, tyres, Wedo motor, some gearbox parts).

I have created the parts list on rebrickable which I'm happy to share:

https://rebrickable.com/users/Doua/lists/250912/

I have manually added :

- 4x red 6.5 shocks hard

- 3x 20 tooth bevelled tan gears

- 1x steering yoke

List doesn't include the Buwizz 3.0 or the 2x Buwizz motors.

It may be easier to build in black since the red tapered panels for the doors are quite rare in red; the flat panels are also a bit more common in black.

 

Edited November 30, 2023 by Doua

[Zerobricks]

2 hours ago, Doua said:

Thanks for this, it looks awesome and very sturdy! I will definitely build this in the future; need to get my hands on a second hand Zetros since it seems to have most of the rarer parts needed (hubs, tyres, Wedo motor, some gearbox parts).

I have created the parts list on rebrickable which I'm happy to share:

https://rebrickable.com/users/Doua/lists/250912/

I have manually added :

- 4x red 6.5 shocks hard

- 3x 20 tooth bevelled tan gears

- 1x steering yoke

List doesn't include the Buwizz 3.0 or the 2x Buwizz motors.

It may be easier to build in black since the red tapered panels for the doors are quite rare in red; the flat panels are also a bit more common in black.

 

Thanks for noticing the issues, I fixed the inventory on my rebrickable page.

[1gor]

It really looks simple in the most positive way, simple and genious at the same time. Makes me more and tempting to use buggy motor in my moc; but for it I would need some pair of 94.3 tractor tire (from Claas Dominator by @eric trax)

Edited December 9, 2023 by 1gor

[Doua]

Question about the gearbox mechanism. From what I understand the WeDo motor doesn't have encoder. And from what I could see in Studio the gearbox doesn't use any kind of clutch. 

Do you operate the gearbox "manually" that is, run/stop the motor manually once the gear changed? Or can the buwizz app gearbox module operate with "dumb" motors? 

Asking because this motor is actually quite expensive here in Australia (40-60$!) and I'm very tempted to go 3rd party for these... An M motor with PU connection would be useful to have either way. 

Thanks! 

[Zerobricks]

You can easily limit the power going to the motor using Power Curves/Current Limits in the BuWizz app.

[Doua]

OK thanks, so you set the power curve so the motor stalls once the gear is in? 

Thanks for the quick reply! 

[Zerobricks]

Motor is manually controlled, so no need to hold the control once shifted. It only takes a second to shift.

[Doua]

Hi,

I've built this today, it's really awesome! Plenty of power in low and enough speed in high. It's the most capable and robust built off-roader I've built for sure. Thanks  for the instructions and keep the models coming, you rock at Technic :D

(Don't have the tapered panels for doors, I'll need to fix something up to protect the battery and motors)

I think this is around my favourite scale for Lego RC cars, light so it's nimble and doesn't stress parts too much, 2 Buwizz motors for plenty of power  at this weight and again, not too much stress on parts. And low part count makes it a good "one evening build" and also easy to disassemble with no remorse :D

The weakest point I found was the vertical bracing of the steering (the two 6L thin liftarms placed vertically). They tended to pop out quite easily in a front collision :x, but also looks like the steering motor was able to push it loose under heavy steering and acceleration. I've reduced the pwm of the steering motor a bit which helps, but I've also reinforced with a T piece in front of everything, which also serves as a central bumper of sorts. The steering is strong and responsive, no issues at all otherwise.

Instructions are very good and clear. A couple notes below for "easy wins" if you ever care to change them:

Step 7: should be viewed from the other side (rotated 180 deg)

Step 10: the black pin should be placed at an earlier or later step (eg step 16) (can't see placement on step 10)

Step 11: should be viewed from the other side

Thanks again!

Edited December 8, 2023 by Doua

[Zerobricks]

Wow, black and yellow looks really great, sounds like you're having a lot of fun with it!

Thanks for the praise and constructive criticism.

Regarding instructions steps, I tried to correct the views, but my Studio just goes a bit wonky and changes all the views... Seems to be a bug, so I will see what I can do.

[Jundis]

Really cool model @Zerobricks !

I need to get my hands on 2 buggy motors... :D

[Another Brick in the World]

On 11/26/2023 at 8:37 PM, Zerobricks said:

To conclude; using this as a base, I wonder what kind of tweaks, improvements and crazy mods other builders will come up with!

Nice model!

When I saw the YouTube video, I was very interested in that 2-speed gearbox and decided to make a Mod of it at my usual Claas Xerion tire size. Hope you like it!