[MOC] Unimog U406

[proran]

Hello fellow Eurobrickers,

I am excited to share with you my passion project which is finally finished after something like five years in the making

Unimog U406

The truck is done in a small scale with not-quite-56mm wheels in Model Team style, but with full Technic frame and mechanics underneath. It features solid axle suspension front and back, steering via steering wheel in a cabin, 4 wheel drive with fake inline-4 engine, front and rear PTO's selectable from the cabin, tipping bed and an adjustable two-point hitch. Here is the illustration, but as usual the best is to watch a video which explains everything in details.

The build is inspired by the article at the Mercedes-Benz own RoadStars.com. If you like Mogs I encourage you to give it a read, the story and photos are beautiful. Anyway, I felt in love with the vehicle and decided to re-create it in Lego in a small scale. I was so passionate about the article and my version of the truck, I went an extra mile and re-created the photos from the article with my truck.

Additional comparison and standalone photos can be found in my Bricksafe.

The project was long in the making and I have a lot to tell about it. I enjoy a good write up here at this forum, so if you are interested the story is below together with some additional photos.

Spoiler

It's all started when I've got myself the 10242 Mini Cooper. That was my first non-technic set post dark ages and after finishing building it I was scratching my head about what do with it. The only right thing to do seemed to re-build into something else. But without constraints of a B-model. I am a Technic guy and I wanted something a bit functional. At the time I was finishing my Mecalac and after all that mechanical complexity I wanted something simple. So I settled on a 4x4 with some suspension, maybe a fake engine, in a size similar to the Mini, so 56-ish wheels. Obviously in dark green. What is the best 4x4 of all times? U406, of course. And it looks gorgeous in dark green.

And then through Google image search I came across an article at RoadStars.com about a restored vintage U406. In dark greek and with red rims. You can see the photo of this gorgeous vehicle above. I immediately felt in love with it, and the project had started.

I settled on recreating the suspension, steering, drivetrain and a fake engine. I knew at this scale, with the 56mm wheels, it will be a challenge. But to make things more interesting I decided to try to implement the working power take-offs. One obstacle was immediately obvious. I 100% wanted to fit a spare wheel on the driver side. That meant that the gearbox for the PTOs must be on the passenger side, and then I need to route it back to the driver side avoiding fake engine and  the steering. I'd struggled big time. That front left corner of the truck is probably the most dense technic assembly I have created. Take a look at the photo below.

I have tried my best in recreating the mechanical details of the real truck. Coil springs were easy, while the torque tube were simply not possible at this scale.  So I opted for two links plus a panhard rod. Given the scale, only one solution was possible for the driven and steered front solid axle - I am not an inventor here, it was used many times before. But I think this is the smallest solid axle you can have. Of course, I needed the portal axles. it's not a Unimog without them. I've decided to use the 8t-8t gear combo to keep the proportions reasonable. The steering turned out to be quite realistic to my taste. The video shows how it works. The drivetrain turned out a bit more complicated that it should be. I didn't want to introduce a negative castor angle at the front and forced the front axle to travel vertically only. That required two universal joints. Their combined length placed the transfer case too way back to have both front and rear drive shafts to sit on one axle and to be driven by a single gear. Instead, I shifted them sideways, placed on different shafts and that allowed me to overlap them longitudinaly. The added advantage was visual realism, as the driveshafts are indeed shifted sideways in the real truck. The rest of the drivetrain and gearbox for the PTO's are pretty straightforward, except for the front PTO which I have mentioned.

I had a couple studs free under the bed, so I have decided to fit a tipper mechanism and an adjustable two point hitch. The hitch turned out to be simple but effective reassembling the real thing quite closely.

From the beginning I had decided to go with a brick built front grille. The emblem was straightforward, but headlamps turned to be quite hard. According to the scale drawing, they were supposed to be smaller than 2x2 bricks. And anyone who tried to build a car with headlamps smaller than 2x2 knows that there are not many options. I think I went through entire Bricklink catalog trying to find something suitable. At the end after many many iterations I had settled on the minifig signal paddle which doubled as a grille trim. The trim portion was too thick and the magic wands would had worked better, but headlamps were the drivers.

Auri from ChromeBlockCity helped a lot with figuring out how to do the front "Unimog" badge. He is a great guy and I highly recommend him for your chrome and custom printing needs.

The bodywork around the front is crazy. On the front "cheeks" the studs are facing in all six directions within a roughly 3x3 space. I am especially proud of the turning signals. Having them stick out the right amount required to build the portion of the "cheek" upside-down. I have tried replicating the most of the details on the side, including a hooded vent, fog lights and mirrors. Doors open, although because part of it is built inverted to fit the ice skate handle, the whole door is quite fragile and it takes a bit of patience to open it without breaking.

My favourite detail of the body work is probably the fuel tank. The standing seam there just gives me smile every time I look at it.

 

I will finish off with a photo of the truck next to it "source". Here you can see, that the Mog is quite small. I am happy with the amount of details and functions I was able to squeeze in.

Please let me know what do you think. I am fully open to criticism despite my passion for this thing. Do you think comparison photos make it look better or worse? One thing I notice is that it sits a bit lower compared to the real truck.

Edited December 29, 2021 by proran
corrected video link

[1gor]

Very cute 

[Jurss]

It looks good, functions are lot. No wonder it took 5 years.

[gyenesvi]

I love this, looks really nice, and I am blown away by those mini axles and the drivetrain, the sideways shift is a nice detail that seems required for multiple reasons, and the portal gears are a nice touch, the steering linkage is compact, it is a piece of miniature art, I am still trying to figure out all its details.. Amazing work!

[GerritvdG]

Nice combination of a small scale, detailed system design and all the possible technic functions!

[keymaker]

It is great model, so many functions in such small scale!

But if I am not wrong, steering wheel steers in opposite direction than the wheels?

[ColletArrow]

This is a stupendous creation - an incredibly good-looking model (I do love dark green!), with a perfect compliement of functions to boot. And those comparison photos blew me away - your skill in matching the model photos to real-life is very impressive, and show off just how good your model is! Fantastic work.

[syclone]

Wow, that thing sure is crammed with functionality! Fantastic replica as well, the time it took to build it shows 

[emielroumen]

Awesome creation!

Minor remark: ensure the universal joint connectors are aligned for the best / smooth gear train. It seems the 2 leading to the front axle are offset a quarter turn.

[Jeroen Ottens]

Wow, such details and so many functions at this scale. Very nice!

[proran]

Thank you very much everyone!

4 hours ago, keymaker said:

But if I am not wrong, steering wheel steers in opposite direction than the wheels?

You are correct . Since everything is so tightly packed in that area, I didn't have much options. Steering is on the left side and 6M link goes to the right side. I wasn't able to flip the 8t around the worm gear either. I thought about reversing it with a pair of 8t, but would introduced some backlash and made the whole module a bit cumbersome. I know it's a fundamental flaw, but I just love how clean it is . Tough call between simplicity and authenticity. I will understand if someone went for something more complex but working correctly.

2 hours ago, emielroumen said:

Minor remark: ensure the universal joint connectors are aligned for the best / smooth gear train. It seems the 2 leading to the front axle are offset a quarter turn.

Good catch, thank you. I am aware how and why they should be aligned and usually pay attention, but here it seems I've missed it. Thanks!

[2GodBDGlory]

2 hours ago, proran said:

Thank you very much everyone!

You are correct . Since everything is so tightly packed in that area, I didn't have much options. Steering is on the left side and 6M link goes to the right side. I wasn't able to flip the 8t around the worm gear either. I thought about reversing it with a pair of 8t, but would introduced some backlash and made the whole module a bit cumbersome. I know it's a fundamental flaw, but I just love how clean it is . Tough call between simplicity and authenticity. I will understand if someone went for something more complex but working correctly.

Good catch, thank you. I am aware how and why they should be aligned and usually pay attention, but here it seems I've missed it. Thanks!

Very nice model! It is crazy complex and good-looking for the size. As for the steering, I really wish Lego would make an opposite-pitch worm gear--it could be so useful sometimes! And to think they could have done it easily with the 3L and 1L ones released more recently--or even when they redesigned the slots on the standard one!

[piterx]

outstanding job dude!

[Good old Lego builder]

Very original! It looks really good. Had to look twice at your first picture to see it was the Lego model. Excellent!

[arieben]

really outstanding model. love it.

[Teo LEGO Technic]

What an amazing build! I can't believe how many functions are packed into that tiny scale!

[proran]

Thank you for all the positive feedback!

21 hours ago, 2GodBDGlory said:

really wish Lego would make an opposite-pitch worm gear

Yes, that will be great indeed. I remember a dedicated discussion about it here some time ago. Another perfect use case for such a part.

On 12/29/2021 at 12:53 AM, Jurss said:

No wonder it took 5 years.

Well, the 98% of it was completed in three years. And I am a slow builder. I've started this project right after my daughter was born, so I will build occasionally on the weekends. After 3 years, t was sitting on the shelf for another two years, while I did some minor tweaks. The grille area took a lot of tuning. I will order some chrome parts, take some photos, then decide that I need to change it, order some more parts, retake the photos, and so on. And then replicating the photos from the article took two or three tries.

Here are some WIP pictures, if anyone interested. As you can see I have started with 2x2 headlights. But they made the whole front look very cartoonish.