Davejsp's Technic Creations

[DavejspTechnicMOCs]

INDEX:

• Introduction (just below)
•   42099 Turbo Pickup (just below on this same post)
•   42095 Racing Buggy
•   RC Black Roadster
•   8048 RC Roadster
•   42140 Rally Car
•   RC Subtractor Racer
•   42109 Le Mans Prototype

 

---

Introduction:

 

Hey everyone!

I'm Dave, and I've been around Technic long enough to remember when the 8880 Supercar came out and amazed me! It was unlike anything I'd seen so far: the independent suspension, the gearbox, the V8 under the hood... I was hooked immediately and picked up a few other sets from that era, but life got in the way and I started my LEGO dark ages, which lasted for about twenty years.

Coming back after such a long gap is a strange experience. The joy of building is still there, if anything it's sharper now because I'm choosing to do it rather than just being a kid with bricks, but the design philosophy has shifted substantially from what I grew up with. The vintage sets I knew had everything exposed, that was the way! You could see everything working. Modern Technic tends to wrap the whole structure in bodywork, which changes the building experience considerably and, honestly, I'm still learning how to think in this studless style. It's a different puzzle.

I'm into RC, so most of my builds end up motorized if the source set allows for it, combining a limited parts inventory with remote control functionality is where the problem gets interesting for me. I see that alternate building (taking an official set and rebuilding it into something completely different) is quite a big thing now, with many people publishing their creations under a designer name and growing their following on social media, amazing stuff, how things have changed since I last checked...

I don't have any fan base and I couldn't care less about that: I build to have fun, and the problem-solving keeps my brain busy. If anything I put here is useful to another builder, that's a bonus, but it's not the point. The point is the build. This thread will serve as a sort of behind-the-curtain look at my design process, the decisions, the dead ends, the things that worked and why, or at the lack of those, just a simple presentation about the model, and also as a discussion hub for all of my MOCs.

If you're interested in my finished designs, all my published MOCs with PDF building instructions and parts inventories are over at davejsptechnicmocs.com. What you'll find here is more about how they came to be.

 

First one up:

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42099 Turbo Pickup

This is an alternate build for the Lego Technic 4×4 X-treme Off-Roader (set 42099), rebuilt into a Turbo Pickup.

 

Functions:

• Remote-controlled drive and steering
• Independent suspension on all four wheels

 

A few things worth noting:

The drivetrain ended up being RWD with a gear ratio of 1.4:1  ->  The two PU XL motors drive the rear differential directly, one on each side. That turned out to be a clean and efficient layout, and it's probably the part of this build I'm happiest with.

Ground clearance is decent for light off-roading: 4 studs at the front axle, 6 at the rear. The planetary wheel hubs aren't used on the rear wheels. The power button for the hub is accessible from inside the driver's cabin without flipping the model over, which matters more than it sounds once you're actually using it.

One thing that made this easy to get running: it uses the original Control+ profile for the 42099 set. No app setup, no reprogramming, you can drive it straight out of the box.

PDF building instructions and parts inventory available at davejsptechnicmocs.com.

 

Photos:

 

Video:

 

Edited 9 hours ago by DavejspTechnicMOCs
Updated information.

[Jurss]

6 hours ago, davejsp said:

don't have any fan base

Very few have here some fan base, but we (at least me) don't "cry" out (loud)  about that.

Otherway, pretty good "speedy" alternative. 

And no need to cover something so much - this is technic, not model team. OK, latest official technic builds wouldn't agree :)

[gyenesvi]

Interesting drivetrain and form factor, even though the wheels feel a bit out of proportion. Could the whole body be lifted a few studs maybe? Then it could have more ground clearance in the middle and at the front/rear bumpers, and the wheels would also not feel so huge?

It would be good to see how this drivetrain can cope with more bumpy roads and some uphills.

[DavejspTechnicMOCs]

2 hours ago, Jurss said:

Very few have here some fan base, but we (at least me) don't "cry" out (loud)  about that.

Otherway, pretty good "speedy" alternative. 

And no need to cover something so much - this is technic, not model team. OK, latest official technic builds wouldn't agree :)

Being a pickup, it just didn't look right being able to see the motors and structure below the dump bed, so, yeah.

57 minutes ago, gyenesvi said:

Interesting drivetrain and form factor, even though the wheels feel a bit out of proportion. Could the whole body be lifted a few studs maybe? Then it could have more ground clearance in the middle and at the front/rear bumpers, and the wheels would also not feel so huge?

It would be good to see how this drivetrain can cope with more bumpy roads and some uphills.

I believe so, the MOC is like this because it's an alternative model of an exixting set and i was limited by the parts on the set. The wheels can perfectly be changed to smaller/narrower ones, and the body structure changed for higher ground clearance, but it won't be a proper B-Model anymore.

[gyenesvi]

1 hour ago, davejsp said:

I believe so, the MOC is like this because it's an alternative model of an exixting set and i was limited by the parts on the set. The wheels can perfectly be changed to smaller/narrower ones, and the body structure changed for higher ground clearance, but it won't be a proper B-Model anymore.

Sure, I know it's a B model, and I meant my suggestion within the constraints of the set :)

[DavejspTechnicMOCs]

2 hours ago, gyenesvi said:

Sure, I know it's a B model, and I meant my suggestion within the constraints of the set :)

Oh, i suppose it can be done, but then, moving pieces around could substantially change the MOC appearance.

[DavejspTechnicMOCs]

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42095 Racing Buggy

Rebuild your Lego Technic "Stunt Racer" set 42095 into a full-fledged, remote-controlled "Racing Buggy" alternative model!

 

About:

The 42095 Stunt Racer holds a particular place for me, it was the first set I bought coming out of my dark age, and the reason I grabbed it was partly sentimental and partly pragmatic. I'd just learned that LEGO was officially discontinuing the Power Functions line, and the 42095 was one of the last sets to include PF motors. As someone who'd always been drawn to RC, I wasn't going to let that pass me by.

It ended up being the set that teached me how the Power Functions line of motors behave and how to wire them, all of that came from tinkering with this inventory. The original model is a kind of amusing tank-like contraption built around pulling wheelies, which is fun in its own right but leaves a lot of the set's potential unexplored. The inventory is small and quite limited, but it's versatile enough to build conventional RC vehicles from it, which is a completely different experience from what comes in the box. This Racing Buggy was one of the first alternate builds I made from it.

It's a lightweight, RC car, RWD driven by one PF L-motor, with auto-centering steering handled by a second PF L-motor, which keeps the driving experience clean and responsive. Runs on tarmac but handles light off-road terrain without trouble. The power button is easy to reach without flipping the model, and while battery swapping requires a quick partial disassembly, it's straightforward enough not to be a nuisance.

 

Photos:

 

Video:

PDF building instructions and full parts inventory available at davejsptechnicmocs.com

 

Edited 10 hours ago by DavejspTechnicMOCs
Updated with better pictures.

[DavejspTechnicMOCs]

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RC Black Roadster

This is a remote-controlled Roadster using Power Functions elements. It's an original, fictional model in the 1:10 scale.

I created this MOC to familiarize myself with the modern LEGO Technic building philosophy and become familiar with the newer gears, fairings, panels, and liftarms. After being away from LEGO for such a long time, this project served as a valuable learning exercise.

 

Features:

- Rear wheel drive through a differential with a gear ratio of 1:1 and powered by two PF XL-motors

- Front wheels steering controlled by one PF servo motor

- Independent suspension on all 4 wheels

- Functional V6 fake engine which can be run either manually (by pushing the car around); or on its own with a dedicated PF M-motor

- All doors are openable and semi automatic, after unlocked, they will open by themselves, just need to be closed manually.

- All doors have some kind of locking mechanism to keep them closed

- There is a switch below the car to engage or disengage the fake engine from the transmission allowing for a better RC performance

 

The transmission is the simplest I could get it to be, in order to reduce friction.

 

I also wanted to keep the steering as simple as possible, it's just a pinion and rack.

 

The independent front suspension requires a more complex build because I really wanted to use those F1 wishbone arms.

 

The independent rear suspension is also very simple to build.

 

The connection between the fake engine and the transmission is one of the most interesting parts of the model. 

The V6 fake engine runs off a dedicated PF M-motor and can spin independently of everything else. But it's also mechanically linked to the main drivetrain, which means it doesn't just sit there looking pretty, it actually responds to what the car is doing. As the car accelerates, the engine spins faster. As it slows, the engine follows.

Regardless of whether the car is moving forward or in reverse, the fake engine always rotates in the same direction. A real engine doesn't reverse. Achieving that meant the mechanism needed to automatically select between two different gear paths depending on the car's direction of travel, making the correct choice every time without any input from the driver.

It's a self-switching directional filter, essentially. Getting it to work was the puzzle at the center of this whole build.

There's also a switch underneath the car that lets you decouple the fake engine from the drivetrain entirely, which is useful if you want smoother RC performance without the mechanical drag of the engine link.

 

Photos:

 

Video:

 

PDF building instructions and full parts inventory available at davejsptechnicmocs.com.

Edited 10 hours ago by DavejspTechnicMOCs
Updated with better pictures.

[Milan]

Beautiful and tidy presentation, as always!

Love the front end of the car!

[DavejspTechnicMOCs]

2 minutes ago, Milan said:

Beautiful and tidy presentation, as always!

Love the front end of the car!

Thanks, just trying to make everything clear for everyone.

[Jurss]

Nice design.

Like how You made shock absorber connection in front. Yes, visual lightnes is lost.

Don't like something about doors. Eeverything else pretty smooth, but doors are somehow rough.

[gyenesvi]

Indeed, the design is pretty neat, and I love the adder mechanism for the drivetrain that allows the engine to run separately and speed up when the model is moving! Great detail! I like the front suspension too, and the door opening/locking mechanisms are also cool additions.

[DavejspTechnicMOCs]

4 hours ago, Jurss said:

Nice design.

Like how You made shock absorber connection in front. Yes, visual lightnes is lost.

Don't like something about doors. Eeverything else pretty smooth, but doors are somehow rough.

Yeah, i didn't have a clear 100% idea about how I wanted the doors to be like, that's why I think they ended up being a bit rough, yeah, I did knwo I wanted a locking mechanism, so the panels i used seemed logical because of the pin holes available and being flat.

1 hour ago, gyenesvi said:

Indeed, the design is pretty neat, and I love the adder mechanism for the drivetrain that allows the engine to run separately and speed up when the model is moving! Great detail! I like the front suspension too, and the door opening/locking mechanisms are also cool additions.

Thanks, for me it was logical to include a way to disconnect the fake engine and reduce friction for maximum RC performance since this MOC is quite heavy.

[gyenesvi]

29 minutes ago, davejsp said:

Thanks, for me it was logical to include a way to disconnect the fake engine and reduce friction for maximum RC performance since this MOC is quite heavy.

Yes, that is a practical thing to have, I had the same problem in my latest MOC (which will be presented soon), not only does it generate some unnecessary friction, but also the engine is running so fast that it is actually generating plastic dust (2x Buwizz motors for drive). Anyway, I don't get how that's implemented with that simple pin, can you elaborate on that? In my model I had to remove an axle to disconnect the fake engine..

[DavejspTechnicMOCs]

There is a picture on the MOC post that shows the mechanism, basically, the only thing that connects the transmission to the fake engine is a single 5l liftarm which has the transmission axle in the middle pin hole with a gear, and has another gear at the top pin hole, as the transmission rotates, this liftarm will go either to the left or right, engaging on different gears, the pin i show in the video connects to the bottom pin hole of the 5l liftarm locking it in a 100% vertical position, keeping it from touching the gears on either side, so no connection to the transmission is active this way.

Edited Thursday at 11:55 PM by DavejspTechnicMOCs

[gyenesvi]

4 hours ago, davejsp said:

There is a picture on the MOC post that shows the mechanism, basically, the only thing that connects the transmission to the fake engine is a single 5l liftarm which has the transmission axle in the middle pin hole with a gear, and has another gear at the top pin hole, as the transmission rotates, this liftarm will go either to the left or right, engaging on different gears, the pin i show in the video connects to the bottom pin hole of the 5l liftarm locking it in a 100% vertical position, keeping it from touching the gears on either side, so no connection to the transmission is active this way.

I couldn't figure out what that part does, but now I get it, nice mechanism, thanks for the explanation (though my model does not have space for it).

[emielroumen]

Very nice! Like the 8094 Mobile Crane lifting boom and jib single motor: http://www.technicopedia.com/8094.html

[DavejspTechnicMOCs]

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8048 RC Roadster

This MOC is a motorized alternative model for the 2010 LEGO® Technic Buggy (set 8048). It is built primarily using parts from the original set, with the addition of a few Power Functions components.

 

About:

The 8048 was the second set I picked up after coming out of my dark age, and finding it was one of those happy accidents that comes from browsing without any prior knowledge of what had been released over the years. I had no map of what LEGO Technic had produced during the twenty years I was away, I was discovering it all fresh, and when I came across this buggy I immediately fell for it. It's exactly the kind of build I gravitate toward: good looking, but with an exposed chassis where you can see the mechanisms doing their work. It also sits at an interesting point in Technic's history, right in the middle of the transition from the studded, skeletal models I grew up with toward the fully covered studless style that dominates today. It has one foot in each era, and that's a big part of why it appealed to me.

Having just acquired the 42095 Stunt Racer and a few Power Functions components along with it, I was eager to try a motorized alternate build with this set. The result is this RC Roadster, and I'm genuinely happy with how it came together.

It's RWD through a solid rear axle at a 1:1.67 gear ratio, driven by a single PF L-motor, with front-wheel steering handled by a PF servo and double wishbone independent front suspension. The build uses only parts from the 8048 set plus a handful of Power Functions components. It's lightweight with very little gear friction, honestly it runs fast enough that taking it indoors is probably a bad idea. The power button is easy to reach, and the IR receiver sits at the rear of the model for optimized signal reception.

 

Photos:

 

PDF building instructions and full parts inventory available at davejsptechnicmocs.com

Edited 9 hours ago by DavejspTechnicMOCs
Updated with better pictures.

[DavejspTechnicMOCs]

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42140 Rally Car

Rebuild your Lego Technic "Transformation Vehicle" set 42140 into a remote-controlled "Rally Car" alternative model and go tear those dirt roads!

 

Features:

• Remote-controlled drive and steering
• RWD via solid rear axle, 1:1.67 gear ratio
• Ground clearance of 2 studs, suitable for light off-roading
• Hub power button accessible from the cabin
• Easy battery swap from underneath the car
• Requires a custom Powered Up app profile (configuration steps included in the instructions)

 

The 42140 is essentially a ripsaw, a tracked, tank-like machine. Which is exactly why I wanted to go in the opposite direction with it. The whole point of an alternate build, to me, is giving someone a completely different play experience from the same bag of parts, and going from a tracked vehicle to a rally car is about as different as it gets from the same set.

The parts inventory makes that kind of leap difficult. Tracked sets don't pack a lot of the elements that make conventional vehicle builds straightforward, panel fairings in particular are sparse, which meant the body had to be constructed almost entirely from liftarms. That constraint is what gives the car its boxy, angular look. That aesthetic is actually not far from how classic Technic sets were built, the structure visible in the shape. Given where I'm coming from as a builder, that felt right. I did push to include as much surface detail as the inventory allowed, so it doesn't look unfinished.

Both rear wheels are driven by a solid axle at 1:1.67 ratio, which gives it enough pull for light off-roading at this scale. Ground clearance is 2 studs, modest, but appropriate given the proportions. One thing worth noting for anyone who builds this: it needs a custom profile in the Powered Up app rather than an existing one, so I've included detailed setup steps directly inside the building instructions. It's not complicated, just a few extra minutes before your first drive.

 

Photos:

 

Video:

 

PDF building instructions and parts inventory available at davejsptechnicmocs.com.

Let me know your thoughts on this one!

Edited 11 hours ago by DavejspTechnicMOCs
Updated with better pictures.

[Jurss]

Looks OK, especially for c-model. I like attention to details - that scoop on the roof.

[DavejspTechnicMOCs]

6 hours ago, Jurss said:

Looks OK, especially for c-model. I like attention to details - that scoop on the roof.

Thanks, it was indeed a challenge to add details because this set lacks parts for that purpose.

[DavejspTechnicMOCs]

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Power-Functions, remote-controlled Subtractor Racer MOC

 

About:

As the name suggests, this MOC is built around a subtractor mechanism. If you're unfamiliar with the concept, a quick online search will give you plenty of explanations and variations, but the core idea is that a subtractor allows a tracked vehicle to turn smoothly and be controlled just like a standard RC car: one input for forward and reverse, another for steering. It's an elegant solution to what is otherwise a clunky control problem with tracked vehicles.

I came across the subtractor while browsing online for different mechanism configurations, I was in learning mode at the time, trying to understand what was out there and what could be replicated in LEGO. Something about it clicked immediately, and I wanted to build one. At that point my parts pool was essentially the 42095 Stunt Racer and a handful of extras, so that became the foundation. What followed was several days of iteration trying to arrive at a configuration compact enough to fit inside a small model, a subtractor takes up space, and making one that doesn't dominate the entire chassis is a genuine puzzle. Getting there was one of the more rewarding building experiences I'd had up to that point.

It's worth noting that while many subtractor designs exist and are well documented, complete models that actually put one to use are surprisingly rare. This is my contribution to filling that gap.

One L-motor handles propulsion while the second is dedicated entirely to steering, unlike traditional tracked vehicles where both motors drive the tracks and turning is achieved by varying their speeds. Because the steering motor contributes nothing to forward motion, I geared the drivetrain down to a 1.667:1 ratio to compensate with additional torque. The model is largely buildable from the 42095 set with some extra liftarms, gears, and miscellaneous elements on top.

 

Control scheme:

 

Photos:

 

Video:

 

PDF building instructions and full parts inventory available at davejsptechnicmocs.com

Edited 9 hours ago by DavejspTechnicMOCs
Updated with better pictures.

[DavejspTechnicMOCs]

deleted

Edited February 16, 2023 by davejsp

[DavejspTechnicMOCs]

deleted

Edited February 16, 2023 by davejsp

[DavejspTechnicMOCs]

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42109 Le Mans Prototype

Rebuild your Lego Technic "Top Gear Rally Car" set 42109 into an RC "Le Mans Prototype" alternative model.

 

About:

The 42109 is one of those sets that never quite found its audience. Most people who bought it did so for the Top Gear branding or to acquire specific parts from the inventory, not because the model itself was compelling. The original build was widely criticized for being slow and visually underwhelming, and the community reflected that: very few alternate builds ever came out of it. That's a gap worth filling, and this Le Mans Prototype is one of my first attempts at doing that.

The goal was straightforward: build something that was faster, better looking, and more detailed than the original (like a modeled interior for example), and use the same parts to do it. The Le Mans Prototype format gave me a direction that suits the set's proportions well.

It's RWD with a gear ratio of 1:3 a significant step up in speed from the stock build, with remote-controlled drive and steering. Batteries are swappable from underneath with no obstructions,  this one needs a custom Powered Up app profile to run though, the setup steps are included in the building instructions, so it's a few minutes of configuration before your first drive rather than anything involved.

I'm planning several more MOCs from this set. It's an underserved inventory that rewards the extra effort, and there's a satisfaction to building something genuinely better than what came in the box.

 

Photos:

 

Video:

PDF building instructions and full parts inventory available at davejsptechnicmocs.com

Feel free to share your opinion about this one!

Edited 10 hours ago by DavejspTechnicMOCs
Updated with better pictures.