MOC - 6x6 Offroad Truck (1/20 Motorized)

[nico71]

Hello everyone,

I create this topic to present you my new creation, a motorized 6x6 Offroad Truck. I usually post in this topic, but I think it will be better for forum search to now separate it as it start becoming very long. Let me know admin if this is a problem.

The model :

A 1:20 scale motorized offroad truck, equipped with 6x6 transmission, working fake engine, steering, full suspensions, manual gearbox, and openable elements. Completed with 80's look with colorful side stripes, quite efficient and compatible with different power sources (Infrared PFS, Buwizz, 2.4Ghz controller).

Specs :

• Offroad model based on International, Western Star and Scammell Truck from 70-80’s
• Dimensions : 41.5 x 13 x 17cm, Scale : 1/20, Wheels : Ø56mm
• Power functions Motors (2x L+1x Servo Motor), battery source : PFS, Buwizz or 2.4GHz
• 6×6 drivetrain with no differential, primary reduction : 12/20 12/20 12/20
• Two speed gearbox (manually operated), ratio : 16/16 or 20/12
• Removable working CAT V8 fake engine
• Steering with rack and pinion, cv-join and oscillating bevel gearing
• Front suspension : live axle with 3 link arms, 2 spring and 1 Panhard rod
• Rear suspension : walking beam axle with parallel links and 2x Panhard rod
• Openable hood with two locking positions, openable doors
• Openable and removable sideboard bed, flatbed with end roller underneath
• Compatible with regular Power Functions Battery or Buwizz / 2.4GHz Battery

See in action :

About the model :

I wanted to build for a while a successor of my Western Star 6900 with AWD this time for more offroady session. So I chose a 6×6 truck with the same 56mm tire and started in 2024 ,first with the chassis and drivetrain. I incorporated some good ideas from other people that I must credit : Gyenesvi for the floating U shape connector on the front axle, enabling to remove one CV Join and gain space. The use of the larger Split connector to fits the heavy CV join, from Apachaihapachai, enabling to build a compact and sturdy front axle. Finally the vertical mounting of the towball arm, from Legov94, to lower the oscillating point and improve the suspensions movements.



All these solution enable to build in a more compact way, and so offer more space to place carefully the motors and the battery box for weight distribution, as well as having more function like the manually operated gearbox with a slow and fast speed. 

Layout of drivetrain, steering, and suspensions :


I also use a bevel gearing for the steering axle as an oscillating axle, to avoid using a CV join and gain space to place the servo motor in the cab, and keep the hood empty to fit the V8 working fake engine. As usual, the engine is removable easily, as well as the sideboard bed, which are functions that I like for playability.



In addition to that, I chose to make the truck in one color with colorful stripping, at first white, but then in black with red / orange / yellow stripe, which remember the Toyota or Kenworth color scheme of 80’s truck.



It result in a nice, sturdy and efficient truck, while keeping the adaptability features for upgrade, like swapping primary gears and battery to fit what people have. Of course the performance are limited to the tires size and the lack of portal hub, so while the approach angle is good, the breakover one is not (as shown in the video). It remains a not-so-heavy truck with nice look which performs safely on rough terrain.

📕 You can find more picture and the instructions on my website : https://www.nico71.fr/product/6x6-offroad-truck/

(instructions are in two versions, PFS IR and Buwizz, with buwizz profile and tutorial)

🧩 Rebrickable inventory : https://rebrickable.com/mocs/MOC-219862/Nico71/66-offroad-truck/#parts

 

Let me know what do you think, do not hesitate if you have questions 👍

[Aurorasaurus]

Impressive! I it a lot, especially the stripe on the body. Is there any reason you are using bevel gears instead of the new non bevel ones in the drivetrain? I think there could be some slight efficiency gains with the new non bevel ones. Nice trick with the steering and moving bevel gear too.

[Bartybum]

Ahh I love the rear suspension, really clever idea to use the ball socket joints the other way round!

[nico71]

6 hours ago, Aurorasaurus said:

Impressive! I it a lot, especially the stripe on the body. Is there any reason you are using bevel gears instead of the new non bevel ones in the drivetrain? I think there could be some slight efficiency gains with the new non bevel ones. Nice trick with the steering and moving bevel gear too.

You are right, in fact I do not have these gears so I use the old one ! I am glad that you notice the oscillating bevel gear instead of CV-join on the steering, it makes me gain some space. Tiny truck but full of tricks !

 

5 hours ago, Bartybum said:

Ahh I love the rear suspension, really clever idea to use the ball socket joints the other way round!

Kudos to Legov94 for the original idea (credited in the text) ! It is indeed a very effective way at this scale to avoid having the walking beam too high, like on my Western Star 6900 TS. 

[Jundis]

This is packed to the maximum! Great work, Nico!

There are so many clever solutions like the vertical mounted ball socket liftarms on the rear for the suspension.

[steph77]

Cool little truck. I also find that this scale is a very exiting one for build models like this one. Good job Nico!

[gyenesvi]

Glad to see the finalized model, amazing truck Nico! I love the retro looks, the stripes are really cool, the suspension is really neat, I especially like the tricks in the rear, the drivetrain/steering also has nice tricks, I like the gearbox operated from the side, and I love how the battery is lowered into the chassis! As for the steering trick, is that bevel gear also sitting in a small U-shaped frame? Or how is it angled while ensuring good contact with the gear above it?

Another question about the diff-looking 2-wide round shape on the second axle: is it to prevent the small gear from falling off?

One more detail I love: the rim covers. That elevates the looks as well! And really nice presentation!

[Paul B Technic]

I love this, the level of detail is amazing.

[LegoTT]

It's very nice, I like the 3 point axle solution, the adjustable gearing on top of the gearbox and the fact the driveline is very strong for the scale.

So it's a great base for trialtruck, I guess the driveline will not fail until you lose wheels.

 

[nico71]

On 5/7/2025 at 8:55 PM, gyenesvi said:

Glad to see the finalized model, amazing truck Nico! I love the retro looks, the stripes are really cool, the suspension is really neat, I especially like the tricks in the rear, the drivetrain/steering also has nice tricks, I like the gearbox operated from the side, and I love how the battery is lowered into the chassis! As for the steering trick, is that bevel gear also sitting in a small U-shaped frame? Or how is it angled while ensuring good contact with the gear above it?

Another question about the diff-looking 2-wide round shape on the second axle: is it to prevent the small gear from falling off?

One more detail I love: the rim covers. That elevates the looks as well! And really nice presentation!

Thanks ! I wanted at first to get the two speed gearbox motorized but it takes too much space and so the baterry box was not at the lower position (in the bed instead) so I prefer to get the gearbox manual and have a flat chassis with the battery inside. I see it as a two-mode shifter (speed or torque) and add an interaction like the openable elements even if it is motorized, it is nice to interact physically with it.

The gearbox is operated by red levers on each side, because the fake engine axle pass on the center. So I use 4l axle with stop to prevent the axle to be easily pull out when we remove the knob : 

Yes the steering 12 bevel gear  which act as an articulated gearing (replace a cv-join) is placed inside a U shape (dark grey on the picture) which is articulated on the perpendicular axis of the bevel gear :

 

For the round cylinder 2x2 on first rear axle, you are right ! It is for replacing the axle joiner and fill the gap to avoid the small tan 12t bevel gear to fall down, because the CV join axle is not sticking out (because I use a thing triangle to lock to drivetrain so it lack 1/2 stud). You can see that I do not need that on the last axle :

 

For the wheel cover, I like to add more details now with non-technic pieces, but I trying that these part are not mandatory for structural. Like that, people can build a cheaper and simplified version if there had not all this small detailed piece (bar, clips etc), so the design will be simpler but still nice to see as composed of technic parts (the bed and flatbed require 114x 1/2 pins for the smooth finishing with tile for instance).

 

On 5/8/2025 at 9:42 AM, LegoTT said:

It's very nice, I like the 3 point axle solution, the adjustable gearing on top of the gearbox and the fact the driveline is very strong for the scale.

So it's a great base for trialtruck, I guess the driveline will not fail until you lose wheels.

 

Thanks ! It is a good base at this scale but it can not compete in heavy truck trial I think over bigger model with bigger wheel, as it lacks some ground clearance and breakover angle. But the drivetrain and suspensions setup can be reuse and extended to match the 81mm wheels without too much trouble, so you will have a very solid trial truck !

Thanks Jundis, Steph and Paul for your comments !