[MOC] Ford Bronco RC (42126 + 42129 dual alternate)

[gyenesvi]

Hi Guys!

I'm happy to share my latest build: an RC Ford Bronco built out of the Raptor and Zetros sets.

A while ago, we were lamenting with @kbalage over how cool this Traxxas RC Bronco is, and how nice it would be to have something like that in Lego form. We concluded that the Ford Raptor set would provide a good base for the body, even the color is a nice match. Looking at the wheels, the Zetros set came into my mind, and that it provides a good set of electronics and heavy duty drivetrain components as well. So the idea was born :) After a few days of sketching the body, it was apparent that it is indeed pretty much possible to shape it quite well just using the Raptor parts. Naturally the fenders are excellent for this model, the orange paneling was just enough and the few system tiles and slopes were great for shaping the iconic edges on the hood in a fairly simple way. And of course the available black front panels were screaming for custom stickers that provide the distinctive Bronco finish. To keep the spirit of the Traxxas model, I made an effort to build the body as a single clip-on piece, connected by only 4 pins. Easy removal and access to the chassis and battery.

Features

- All wheel drive with 3:1 gear ratio RC gearbox
- Well articulated live axle suspension on both axles (4-link front, 2-link rear, with Panhard rods)
- Detachable bodywork as a single piece, easy access to battery
- Complete interior including 4 seats and a dashboard
- Openable doors, hood and trunk cover
- Expedition kit: spare wheels, roof rack, roof lights, toolbox
- The model can be controlled with the Zetros profile of the Control+ app

Action video

 

Here I'd like to share the design process and more details about it.

Bodywork and interior

Let's start at the beginning :) Strange as it may sound, this model was developed from outside in, and the complete body was designed virtually first. And I have to say it was a really good process for a couple of reasons. I started with scaling to the Zetros wheels to give me a wheel base length/width to work with. Those wheels are a nice match for the fenders in the Raptor, though I was a bit afraid that it would be hard to avoid them rubbing when steered, so I decided to build it fairly lifted. That gave the fender positions immediately. I started the body with the key part, the front. For one, it is a stud shorter (flatter) than that of the Raptor, but still I wanted to build it so that some stickers (lights and Bronco text at least) could nicely be applied to it, as I knew they would be key to make it look authentic. Then the iconic ridges on the edge of the hood; at first I though they would be hard to build, but some flip-flop beams allowed the attachment of both the fender and another beam above it, while some curved sloped system bricks, brackets from the Zetros and small orange tiles make a perfect corner piece at the front, luckily attachable from below in a stable way. I've got to say I see a lot of potential in using system slopes/tiles to complement technic builds. The openable hood itself is simple, but as it's narrower than the Raptor's, its front silhouette could be shaped more smoothly using the wing panels. Onto the doors; I tried to make their hinge and the area in front of them blend in nicer than on the Raptor. And those phones from the Zetros add a great touch as handles :) Rear doors could not be made openable, but at least this way the body continues seamlessly and also integrates nicely with the rear fenders and the slight upwards bend above them. I added some black tiles as stripes below the doors to avoid too much beam stacking and make the side a bit more decorated and not so flat. The top is just the right length for some available large black panels, and the side pillars were slanted to give it a nice rounded shape from all angles. The black connectors from the Zetros were instrumental here. Also, luckily the Zetros includes some bricks for lights, so I could brick build the rear ones at least. Finally, I used the buggy wheel as spare one, but covered it with the big dish from the Zetros's poles to make it more color consistent. I knew those parts would be useful for something, as well as those fake spokes :)

This gave me the complete size of the model and I was able to see how much space I have for the internals, so I could move on to building a chassis.

Chassis, drivetrain and suspension

I must admit that my first attempt to build a chassis failed completely. It was a bit too ambitious I think, I tried to squeeze too much in. I had the idea that maybe there would be enough space for the V6 fake engine of the Raptor along with all the electronics. Also, I wanted to see if I can build a rear axle with a diff-lock in a smaller package than that of the Zetros itself. I did build these, but the chassis was weak and flexing at the front, the rear axle had a key gear that could slide out of place and was impossible to fix properly as the diff locker clutch was right in the way, and the cables were impossible to route in a way that the body could be placed on top of it. (I haven't yet given up on the diff-locked rear axle idea though)

So I abandoned these ideas and designed a less packed but compact and sturdy chassis instead. Instead of the rear diff-lock, I went for a high/low gearbox, and I discovered that with a simplified rear suspension, I can make enough space to allow the usage of the old differential piece and make a 3:1 gear ratio. The suspension came out pretty clean for both axles. The front one is a complete 4-link setup, with an additional Panhard rod. It has a fair amount of articulation, but not too much, which is good so that the front wheels don't get stuck in the fenders so easily. Now I know that the real (modern) Bronco has independent front suspension, but I built it with a live axle for some reasons. The Traxxas model has live axles (maybe because they use a generic chasiss), and building a 15 wide independent driven and steered suspension is only possible with a floating differential (even the Ford GT's new joint part will not be useful for planetary hubs), which is a bit of a dirty solution for an RC model, and the independent front suspension would not provide as much ground clearance either. Also, the classic Bronco had live axles, so I think it's okay here as well :) The rear suspension is simplified with only one CV joint and two lower links. It's like the ball joint suspension in the Raptor set, but without the ball joint itself to save space and allow the usage of the heavy duty CV joint. With a Panhard rod placed low enough to keep the axle properly centered this setup works surprisingly well. It is essential to keep it properly centered, otherwise it would exert sideways force on the incoming drivetrain as it is not able to follow sideways movement due to the single joint, and would result in significant friction. Also, the placement of the rear springs is quite realistic I think, and it prevents the axle from tilting forwards under power (a problem I had with my Jeep Wrangler alternate of the Zetros with a similar setup). Furthermore, as here I am using a 4L axle with stop in the middle as the incoming drivetrain, the axle is stopped at the pinion gear end, so it cannot slide towards the rear diff and out of the CV joint (it happened with my Wrangler as that one used a 3L axle with no stop in the middle). The rear axle can use both hard and soft springs, and articulates quite well with both. Naturally, it has more flex with soft springs, but sits in slightly (depending on how heavy the batteries are).

Once the chassis was working, it was ready for marrying it with the body. I definitely wanted to try make it modular, and the body detachable in a single piece. Somewhat unexpectedly, the most challenging part here was the routing of the cables in a way that they are not in the way for the body. The battery being placed low in the chassis helped a lot here, and I managed to route the cables on the floor and in between the chassis beams on the sides, guided by cable clips (see some images in the gallery). Also, the cable length of the medium motor used for the gearbox is quite short, so I had to place the motor counterintuitively such that its output is at the front so that the cable can reach the battery (just barely enough this way). So in the end, the body is not fixed to the chassis in the middle, only at the two ends, held by 4 pins and it simply clips on from the top, but is still quite stable, does not fall off easily (the model can even be lifted carefully held at the two ends).

Interior

Finally, the interior was designed after the chassis was ready when I saw how much space was left. As I could arrange the electronics nicely out of the way, I was able to fit 4 seats in, and cover the battery in the trunk, making the cover openable to allow turning on the battery. The dashboard is also mounted onto the body, hanging in from the top. The whole body & interior was then redesigned in terms of connectivity to be able to build it in a single piece while keeping it somewhat solid. The build sequence was not easy to make in a way that things are neither hanging in the air for a long time, nor are the two sides required to be bent out to fit the internals in. Interestingly, it is the rear seats that hold together the two A pillars, which form the backbone of the body. The gearbox mechanism is right between the two front seats, which are fixed to the sides of the body.

Expedition kit

This time I decided to add more decorations in the form of a roof rack, as the car looked a bit naked with the flat roof (although true to the Traxxas model). I added a light kit, a roof rack, and some ideas borrowed from a friend: a spade, a toolbox, a handheld reflector, along with another spare wheel and the fire extinguishers from the Zetros.

Here are some images of the model in its natural environment.

More images are in my Bricksafe gallery.

Building instructions are available on Rebrickable, and stickers are available from Forwart Sticker.

Let me know how you like it!

Cheers,

Viktor

[kbalage]

I'm really glad we had that discussion, you did an excellent job! :) Can't wait to climb my mountain of review sets and start building this beauty!

[2GodBDGlory]

Very nice! That color and tire setup does look great, and makes for a nice model of a very cool vehicle!

The double-alternate setup is also nice, and it looks well-engineered too!

 

[Thirdwigg]

As soon as the raptor came out, I knew a Bronco alt build would be coming. I'm happy it's finally here. Well done, and I think it was a good idea to add 42126 with 42129 for a more fleshed out build. Great job. 

[Zerobricks]

Ain't she a beauty. Well done indeed, having a seperate body is simply icing on the cake. Btw, maybe you could do a raptor Bronco version which is much wider and could use independent front suspension, you might need an additional U joint or small cc joints for it though. 

 

[Daniel-99]

This model is so good, that I can not let myself to skip this post! Both chassis and bodywork are the best examples for Lego C+ RC cars.

Did you tried to build a front independent suspension as the real in the real car?

[HorcikDesigns]

Wow, good job! I love the fact it is alternate model. 

[Jundis]

What a beast, great job!

The tractor tires barely fits in the wheelarches, but man do they look good! :D

[gyenesvi]

Thanks guys for all the responses, I'm really happy that this model is getting liked a lot both here and on RB / FB :)

16 hours ago, kbalage said:

I'm really glad we had that discussion, you did an excellent job! :) Can't wait to climb my mountain of review sets and start building this beauty!

So am I glad, it's always inspiring to have such discussions with like-minded people, usually results in many cool ideas :)

16 hours ago, 2GodBDGlory said:

Very nice! That color and tire setup does look great, and makes for a nice model of a very cool vehicle!

Thanks, indeed, I think I will use orange-black in more builds in the future, and also orange-DBG has a lot of potential I think!

16 hours ago, Thirdwigg said:

As soon as the raptor came out, I knew a Bronco alt build would be coming. I'm happy it's finally here. Well done, and I think it was a good idea to add 42126 with 42129 for a more fleshed out build. Great job. 

Thanks, in retrospect it does seem obvious, not sure why it didn't come to anybody's mind sooner.. And two sets that complement each other have much potential, while still making it easy to reproduce the model.

15 hours ago, Zerobricks said:

Ain't she a beauty. Well done indeed, having a seperate body is simply icing on the cake. Btw, maybe you could do a raptor Bronco version which is much wider and could use independent front suspension, you might need an additional U joint or small cc joints for it though. 

Thanks a lot for the nice words :) Also, I'll look into the Raptor Bronco version. I am interested in building a version with independent front suspension. Maybe I'll even give the floating diff a try to see how well it would work out.

14 hours ago, Daniel-99 said:

This model is so good, that I can not let myself to skip this post! Both chassis and bodywork are the best examples for Lego C+ RC cars.

Did you tried to build a front independent suspension as the real in the real car?

Thanks, glad you didn't skip :) Truth is I did not try the IFS version yet. I somewhat quickly decided that I'd go with the floating axle setup. But now I am getting more intrigued about the IFS. Especially that I have just seen a nice example for that from @HorcikDesigns

One thing that would be different with IFS is the steering, which has advantages and potential problems as well. On the plus side a rack based steering would be more powerful than this linkage based variant. On the other hand, the steering motor would need to be centered, and that way there wouldn't be enough space for the gearbox motor (and all the related gearing and clutch protection) next to it, as it is placed now.. So not sure the if that could be redesigned while keeping the complete clip-on body..

13 hours ago, HorcikDesigns said:

Wow, good job! I love the fact it is alternate model. 

Thank you! So what's your experience so far with the floating diff IFS with planetary hubs? Any weak points so far? I saw you did 3D print a custom diff cover and chassis strengthening piece for it. What did warrant that? Needed for structural rigidity or more for aesthetics and gear protection?

13 hours ago, Jundis said:

What a beast, great job!

The tractor tires barely fits in the wheelarches, but man do they look good! :D

Thanks a lot! Agree they look great, definitely wanted to use these instead of the buggy tires. And actually I find that the tires fit the wheel arches better than I anticipated. The rear ones just perfectly sink into the fender flares when it articulates, and even when it rubs it it does not get stuck. On the front, as it turns, it goes nicely behind the edge of the fender flare, so it does not get stuck as easily as I thought it would. However, it can get caught up in the rear mounting point of the front fender flare on the inside (as the wheel is pushed back by a rock), as that axle hole sticks out a bit, the inner surface is not smooth (maybe the flare part could be made better if the orientation of the mounting point would be perpendicular).

[Jundis]

Strangely, there is only one current 43.2 mm wheel type available, maybe Lego will come up with a better center frame one in the future as we might get more and more tires and therfor cars/trucks/whatever for this scale (42124, 42129, 42154, 42156?, 42160?, 42161?)

[proran]

I am in love with this thing. The body work is an eye candy! I like that you went with a very simplistic stickers for the front lights, instead of trying to make it photo realistic. I think that suits a Lego model much better. But to be honest the moment I saw your name next to the Bronco title, I've jumped to the chassis. And I wasn't disappointed, to say at least! Such a clean design. Really appreciate your decision to go with a simpler and sturdier solution. The side render is just wow. No negative castor at the front, super compact steering through the linkage, angled lower "wishbones" from your previous MOCs. And then a super simple rear setup. It's a beauty. Congrats on a great model and special thanks for the write-up, I really enjoy reading about the design process.

[gyenesvi]

18 hours ago, proran said:

I am in love with this thing. The body work is an eye candy! I like that you went with a very simplistic stickers for the front lights, instead of trying to make it photo realistic. I think that suits a Lego model much better. But to be honest the moment I saw your name next to the Bronco title, I've jumped to the chassis. And I wasn't disappointed, to say at least! Such a clean design. Really appreciate your decision to go with a simpler and sturdier solution. The side render is just wow. No negative castor at the front, super compact steering through the linkage, angled lower "wishbones" from your previous MOCs. And then a super simple rear setup. It's a beauty. Congrats on a great model and special thanks for the write-up, I really enjoy reading about the design process.

Thanks a lot, glad you like it! I agree on the simplicity of the stickers, the first version was more photo-realistic but more overcrowded, so we simplified it :) And glad you appreciate the chassis design and the proper geometry, that's always important for me.

On 2/22/2023 at 11:31 AM, Jundis said:

Strangely, there is only one current 43.2 mm wheel type available, maybe Lego will come up with a better center frame one in the future as we might get more and more tires and therfor cars/trucks/whatever for this scale (42124, 42129, 42154, 42156?, 42160?, 42161?)

Sure, it would be nice to have more options in this scale, let's see what this year brings :)

[blondasek]

I have to say.. this makes me to buy both sets. If I grab them for a nice price, you will see one more sold instruction on rebrickable. Amazing.

[gyenesvi]

9 hours ago, blondasek said:

I have to say.. this makes me to buy both sets. If I grab them for a nice price, you will see one more sold instruction on rebrickable. Amazing.

Thanks, that's great :) There's plenty of other stuff to build from them as well, so you shouldn't regret it!

 

Edited February 23, 2023 by gyenesvi

[Krxlion]

Great model not gonna lie :) I really like the gearbox and I suddenly found out that I know you from the rebrickable page (I am new to eurobricks) and I actually bought one of your instructions from rebrickable (zetros C-model with gearbox 3:1). :D

[R0Sch]

Very cool MOC. Almost RC level playability/functions. Looks good too (and I don't mean the pretty rocks from the video :P). The Zetros was a good set, but too slow and too stiff suspension and the Raptor cannot even be called an offroad truck without proper 4x4, so combining both sets was a good idea.

[langko]

Very good model! I like this a lot more than both the Zetros/Raptor sets. The easily removable bodywork is a nice touch, I've experimented with this too and its not easy to implement. Great write up as well, interesting to read. Thanks for sharing!

[gyenesvi]

20 hours ago, Krxlion said:

Great model not gonna lie :) I really like the gearbox and I suddenly found out that I know you from the rebrickable page (I am new to eurobricks) and I actually bought one of your instructions from rebrickable (zetros C-model with gearbox 3:1). :D

Thanks, hope you liked it :) Indeed, it's the same gearbox, but I managed to cram it into a chassis with front live axle, which I hadn't thought would be possible at this size in the beginning. In the IFS buggy it was easier.

18 hours ago, R0Sch said:

Very cool MOC. Almost RC level playability/functions. Looks good too (and I don't mean the pretty rocks from the video :P). The Zetros was a good set, but too slow and too stiff suspension and the Raptor cannot even be called an offroad truck without proper 4x4, so combining both sets was a good idea.

Thank you, well the speed is definitely far from RC models, but as a rock crawler it's okay. Only a bit faster than the Zetros at low gear, but high gear is much better when on flat surface :)

8 hours ago, langko said:

Very good model! I like this a lot more than both the Zetros/Raptor sets. The easily removable bodywork is a nice touch, I've experimented with this too and its not easy to implement. Great write up as well, interesting to read. Thanks for sharing!

Glad you like it and appreciate the writeup. Indeed, the removability of the body limits and complicates things quite a bit, but it's great to have when you need to tinker with the chassis / clean it..

[rm8]

Cool build!

You are increasing your skills with every model

Modularity is good and make many things easier

[gyenesvi]

13 hours ago, rm8 said:

Cool build!

You are increasing your skills with every model

Thanks for the kind words, with practise we learn :)

13 hours ago, rm8 said:

Modularity is good and make many things easier

True (when there's enough space and parts to make it possible), and I also think it can make structures cleaner when you think modularly.

[Paul B Technic]

This is really well designed and built, well done.

[gyenesvi]

On 2/28/2023 at 11:53 PM, TangersTechnic said:

This is really well designed and built, well done.

Thank you!

[piterx]

This is by far one of the most well designed and and beautiful offroaders i've seen in a long time!
Sick build!

[gyenesvi]

On 3/5/2023 at 9:37 PM, piterx said:

This is by far one of the most well designed and and beautiful offroaders i've seen in a long time!
Sick build!

Thanks for the kind words, glad you like it!

[KirTech LAB]

This is an awesome idea to combine a shelf model and RC set. Very cool model!