[MOC] Red Wolf - 4WD RC Race Buggy /w Buwizz

[Didumos69]

Instructions are on Rebrickable under the name '4WD RC Race Buggy + BuWizz MOD. This includes instructions for the PoweredUp version and as a bonus instructions and a parts list for the BuWizz version.The instructions are on Rebrickable under the name '4WD RC Race Buggy + BuWizz MOD'. In addition to the instructions for the basic PoweredUp version, the instruction files of this MOC include - as a bonus - a parts list and instructions for the BuWizz version, which uses 2 x BuWizz 3.0 Pro + 4 x BuWizz Motor. -- The parts list for the BuWizz version differs from the inventory listed in this MOC. -- The list of LEGO-parts (.csv) and the list of other parts used (.pdf) for the BuWizz version can also be found here and here respectively.

This model uses the following 3rd party parts:

• 2 x BuWizz 3.0 Pro+ 2 x BuWizz Motor (1 BuWizz and 2 motors in one pack, so you need 2 packs)
• 2 x Aluminium Metal Beam Bearing Block liftarm compatible with Lego Technic
• 2 x Traxxas Model#1985 PTFE-coated Washer, 5x8x0.5mm (they come in packs of 20, so you need 1 pack)
• 4 x RC4WD Tires Dick Cepek Mud Country 1.9 (they come in packs of 2, so you need 2 packs)
• 4 x 1.9 Foams RC Tire Foam Inserts Black 4pcs (4 pieces in one pack, so you need 1 pack)

Hi,

It's been a while, but a year ago I got my hands on the Audi RS Q e-tron set with the new yellow differential gears and the new wheel hubs for the strong (RC-capable) CV-joints. I also got 2 Buwizz 3 units and 4 Buwizz motors (their buggy motor remake) and with the hubs and diffs from the Audi I could finally continue a concept that I have working on every now and then over the past few winters.

The idea was to create an off-roader with ruggedness and capabilities even better then my Greyhound 4WD RC Buggy and

• Make a build with an easily detachable body, just like with real RC cars
• Make the Buwizzes easily removable, so you can use them for other models
• Make it easy to reconnect the steering ball joints if impact caused them to detach
• Obtain a direct connection between the wheel hubs in the steering setup, without slack

The wheelbase is 3 studs shorter and the track-width 2 studs narrower compared to the Greyhound. The roof top is also 2 studs lower. All in all I strived for a little bit more of a race look.

One of the ideas that I started with (about 3 years back), was a setup with 9L steering links that are positioned with a small angle, such that they are actually a little too short (about 0.8%), which gives them a nicely tight fit. When you use them at both the front and rear side of the steering setup, this won't introduce any toe-in or toe-out. With this setup any rotation in one wheel hub translates to immediate rotation of the other wheel hub, without any slack.

I also wanted to use 4 Buwizz motors to make the whole thing capable. At a certain stage I had a setup with the old wheel hubs and the new RC-capable CV joints, but I could only make that work for a RWD model, not for 4WD. With the new differentials and the new wheel hubs from the Audi RS Q e-tron I could revert to 4WD and I could finally complete this project.

Still, getting the max out of 4 Buwizz motors turns out to be challenging. The main problem I ran into: the axle driving the rear differential melted and also caused the 5x7 frame around the differential to deform. I had to resort to 3rd party metal beams with ball bearings to avoid overheating of the axles driving the differentials (Aluminium Metal Beam Bearing Block liftarm compatible with Lego Technic). This works great!

I also ran into the issue that the output axles of the differentials worked themselves out of the bevel gears inside the diff and started skipping, gradually carving a hole in the bevel gears. The problem was that the drive shafts had too much play in them. This I could resolve by adding a support halfway the drive shaft, which locks up the CV-joint exiting the differential (see image). In this image you also see the LBG #1 connectors that prevent the steering links from detaching. When they do detach, you only need to temporarily remove the connector to put them back.

The next issue was that the big yellow gear attached to the differential house disconnected form the differential house under heavy load. That caused the differential to skip and to carve into the parts bracing it. To resolve this I've added a thin washer from Traxxas between the gear-side of the differential and the parts bracing it (Traxxas Model#1985 PTFE-coated Washer, 5x8x0.5mm). That avoids the differential house from disconnecting without causing any added friction.

Finally, I've added RC crawler tires from RC4WD (RC4WD Tires Dick Cepek Mud Country 1.9). They are from much softer rubber than LEGO tires and for that reason they have much better grip and they absorb a lot beating. That also reduces the chances of having an entire wheel coming off, which never happened to me with these tires. Only when I crashed. These tires come with soft foam inserts. For my purpose, I replaced the included inserts with bigger ones (1.9 Foams RC Tire Foam Inserts Black 4pcs), to get a little more pressure in the tires. That makes them more suitable for racing.

Edited February 3 by Didumos69

[Lixander]

The only thing I can say....great work!

Also, you used only the small cylinders for the suspension? And do you connected 2x BuWizz motors with one axle?

 

 

Edited February 3, 2024 by Lixander

[Thirdwigg]

Welcome back @Didumos69. Great looking off roader, and I'm happy you were able to take advantage of some new parts.

[Krxlion]

Oh yes! I can already see by the look of those pictures it is very robust, which I love. I remember when I saw your Greyhound and wanted to build something very similar to it! Furthermore, I was continuously watching your heavy-duty wheel hubs videos, haha. One thing I really hope you will still preserve is that smooth working suspension. The weight to chosen springs was marvelous. Please polish the model as much as you can and hopefully we will see a full video soon, so we can learn a few things ourselves. ;)

PS About new hubs, am I the only one that feel like the ones with planetary reduction have better grip than newest from Audi RS Etron? But don't get me wrong, they are both very good at keeping those wheels, but I find planetary ones to that job better.

Edited February 3, 2024 by Krxlion

[Aurorasaurus]

Looks awesome. I'm a huge fan of the greyhound, and it looks like you've done it again! Im excited to perhaps build it, it looks really sturdy.

[Jurss]

8 hours ago, Lixander said:

And do you connected 2x BuWizz motors with one axle?

Also first question that came to my mind. But it works. Just how long it will last?

[Aurorasaurus]

15 minutes ago, Jurss said:

Also first question that came to my mind. But it works. Just how long it will last?

Probably quite a while since that axle isnt really experiencing anything that could make it break, unless you accidentally run one of the motors the wrong way around. Theres other weak points that would break first like the diffs or cv joints.

[Lixander]

1 hour ago, Jurss said:

But it works. Just how long it will last?

The other thing I wanted to ask :))

I had some problems with 2x buggy motors (MouldKing ones) not moving a heavier trophy-truck and when I contacted the seller, one of his first concerns was not to have 2x motors connected with one axle, the reason being that it might damage the motors by doing so.

Now I am wondering: connecting the outputs of 2x buggy motors with one axle damages the motor too or just breaks or deforms the axles, frames and differentials?

 

[Didumos69]

Thanks for the kind comments everyone!

12 hours ago, Lixander said:

Also, you used only the small cylinders for the suspension? And do you connected 2x BuWizz motors with one axle?

Yes I only use the small springs now. They're cheaper and take up less space. The travel is still such that the bottom can almost touch the ground when the springs are fully compressed. I reserved space for a third spring for each wheel so I don't need to do any concessions to suspension travel. I expect such a third 3 spring to be needed in the rear once I attach the body.

Yes I use 2 Buwizz motors on 1 axle.

12 hours ago, Krxlion said:

PS About new hubs, am I the only one that feel like the ones with planetary reduction have better grip than newest from Audi RS Etron? But don't get me wrong, they are both very good at keeping those wheels, but I find planetary ones to that job better.

I did not experience that. The wheels did come off on occasions, but only when there was impact.

3 hours ago, Jurss said:

Also first question that came to my mind. But it works. Just how long it will last?

3 hours ago, Aurorasaurus said:

Probably quite a while since that axle isnt really experiencing anything that could make it break, unless you accidentally run one of the motors the wrong way around. Theres other weak points that would break first like the diffs or cv joints.

1 hour ago, Lixander said:

The other thing I wanted to ask :))

I had some problems with 2x buggy motors (MouldKing ones) not moving a heavier trophy-truck and when I contacted the seller, one of his first concerns was not to have 2x motors connected with one axle, the reason being that it might damage the motors by doing so.

Now I am wondering: connecting the outputs of 2x buggy motors with one axle damages the motor too or just breaks or deforms the axles, frames and differentials?

I've tested the setup a lot and sofar nothing broke. It even happened that I went from full throttle forward to full throttle backward. No clicking gears, no broken parts. I'm using the high speed/less torque outputs of the motors, that will probably also make a difference.

Of course, I want a speedy model that is not light-weight, so you have to know what you're doing, also as a driver. The RWD setup with 4 motors on a single axle showed me that as long as the motors can deliver their speed, all works fine. But when doing many sharp turns, which cause the speed of the rear wheels to drop significantly, problems arose. Less RPM means more torque and eventually this caused the axle to overheat (not just break, but overheat), exactly at the point where it enters the 5x7-frame with the diff inside. Also the frame overheated. Eventually the overheating made the axle melt and then it simply winds up until it breaks.

Now that I have a 4WD setup nothing like that happened and I can make whatever turns I like. I do keep in mind though that the motors need to be able to deliver their speed. So I'm not gonna ride it up a steep hill for 5 minutes straight.

Btw, while experimenting with the RWD version, I also ran into the issue that the output axles of the diff worked themselves out of the bevel gears inside the diff and started skipping, gradually drilling a whole in the bevel gears. The problem was that the drive shafts had too much play in them. This I could resolve by adding a support halfway the drive shaft, which locks up the CV-joint exiting the diff. See image.

In this image you also see how the wishbones are form-locked with thin liftarms spanning their width. And you can see the LBG #1 connectors that prevent the steering links from detaching. When they do detach, you only need to temporarily remove the connector to put them back.

Edited February 4, 2024 by Didumos69

[Lixander]

Ok, I understand.

Also, thanks for the detailed answers ;)

Edited February 4, 2024 by Lixander

[ninoguba]

This is such a nice build! Looking forward to the instructions.

[Didumos69]

Thanks!

I've built the removable body. Not all parts have arrived yet, so the colors are not final yet, but here are some early videos of some indoor playing. Sorry for my bad driving skills 

Edited February 7, 2024 by Didumos69

[Aurorasaurus]

Looking amazing, I'm excited to see how you finish this.

[Didumos69]

Thanks!

Another test outside today:

Results are pleasing:

Edited February 8, 2024 by Didumos69

[Aurorasaurus]

That looks like it was handling really well. Did you encounter any issues?

And, a side note, do you think it could fit 6 buwizz motors without too much modding?

[damirnis]

Hello, how are you?

I haven't been building anything since I was 14, which was a long time ago. I only recently rediscovered Lego as I have a 5-year-old, so it's a great learning tool. The builds you do are amazing and thank you for sharing the experience. Your Greyhound made me think I could make something similar, and the goal is to make it as compact as possible, so thank you for your creations. 

 

But I have one question. I am using Zetros Hubs, and with BuWizz hubs and motors, I had my wheel fall off a couple of times, so I wanted to see how it is with Audi ones and also the black Ferarri rims, 

 

 

 

[Didumos69]

On 2/8/2024 at 8:11 PM, Aurorasaurus said:

That looks like it was handling really well. Did you encounter any issues?

No, all went well.

On 2/8/2024 at 8:11 PM, Aurorasaurus said:

And, a side note, do you think it could fit 6 buwizz motors without too much modding?

It may not look like it, but it's very tightly packed inside. So adding 2 more motors will require serious rework.

6 hours ago, damirnis said:

But I have one question. I am using Zetros Hubs, and with BuWizz hubs and motors, I had my wheel fall off a couple of times, so I wanted to see how it is with Audi ones and also the black Ferarri rims, 

Nice model! I did not have any wheel drop off while driving. It did happen when I hit something hard. On such occasions it even happened that the tires came off the rims.

If it would happen I personally have no problem driving set screws inside the pins of the hub. But the downside of that is that the wheels don't come off at all, while them coming off on serious impact is actually a good thing as it absorbs part of the impact energy.

I have experience with these set screws. They seems to be the perfect solution.

[damirnis]

7 hours ago, Didumos69 said:

Nice model! I did not have any wheel drop off while driving. It did happen when I hit something hard. On such occasions it even happened that the tires came off the rims.

If it would happen I personally have no problem driving set screws inside the pins of the hub. But the downside of that is that the wheels don't come off at all, while them coming off on serious impact is actually a good thing as it absorbs part of the impact energy.

I have experience with these set screws. They seems to be the perfect solution.

Thank you very much I'll post the change once I get the new hubs. And hope to see the new model on rebrickable. 

Edited February 11, 2024 by damirnis

[Another Brick in the World]

Very nice model! it seems to perform very well even at full throttle. The axles look very interesting too, and very sturdy. Would a 3D file or building instructions be possible?

[amorti]

1 hour ago, Another Brick in the World said:

Very nice model! it seems to perform very well even at full throttle. The axles look very interesting too, and very sturdy. Would a 3D file or building instructions be possible?

The last guy who made PDF instructions for @Didumos69 spent weeks of evenings doing them, then never got a reply.

Diederik - what's up with that? I'll ask here since you ignored my PM's for months.

[BusterHaus]

@amorti Are you talking about the instructions for the Hammerhead? 

[amorti]

8 hours ago, BusterHaus said:

@amorti Are you talking about the instructions for the Hammerhead? 

Can't even remember the name of it, but it was a rebuild of the zetros.

[Didumos69]

On 4/15/2024 at 10:06 PM, amorti said:

The last guy who made PDF instructions for @Didumos69 spent weeks of evenings doing them, then never got a reply.

Diederik - what's up with that? I'll ask here since you ignored my PM's for months.

I know I'm not much of a team player and should have made that perhaps even more clear than I did. I'm sorry for that. I'll send you a PM.

If there's anyone else I need to mea culpa to, let me know. I'm in a good mood now.

[Toshi]

After building the Greyhound, Rocky and the Hot Trot, I would love to get building instructions for this one also!

…I would likely try to come up with an alternative power source, since I think BW3 is way too expensive, but this model would be a good motivation to finally getting around to doing that!

Any chance you will make instructions in some form and a possible timeframe for it to happen?

[New_User]

No fake V8 this this time?