[MOC] Matt's Off-Road Recovery Heavy Wrecker

[Anto]

Three years after my previous model, the Hoonipigasus, here is finally a new MOC that I can present! 

But what’s that super long title? In other words, it’s a truck made by Matt! A truck designed to rescue vehicles stuck or damaged in off-road environments.

 

 

Introduction

This is a commissioned MOC by Benjamin Lorteau. He wanted this truck to be 100% manual, using the wheels from the Audi RS Q e-tron #42160, and featuring several steering modes thanks to two knobs, one controlling the front axle and the other the rear axle. I was free to do pretty much whatever I wanted as long as the initial constraints were generally respected. Here's a little paragraph from Benjamin:

Quote

Since the recent enshittification of YouTube, the Matt's Off-Road Recovery channel is among the very few I still follow. And for a simple reason: I fell in love with the Heavy Wrecker, a vehicle built from scratch by Matt's team to perform winching missions in the numerous natural parks around that welcome off-roading amateurs. On the other side, I got reacquainted with LEGO during the pandemic, buying bulk collections to restore the sets that came into it and reselling them once complete and built again. It was only a matter of time before I would be looking for a MOC (My Own Creation) of the Heavy Wrecker; no luck, which led me to partner with Antonin who designed a model as close as the original as possible.

When the idea was proposed to me, I immediately saw strong potential. I thought it was possible to build something very interesting, the opposite of what is increasingly found in the Technic range, with lots of mechanically boring cars. The project would be based on an innovative mechanism allowing multiple steering modes, working in a similar way to the Claas Xerion #42054, while still being compatible with suspended axles. The model also had to stand out with a very good building experience. I will come back to this specific point later.

 

 

Design

I tried to reproduce the lines of the real truck as faithfully as possible. The visual appearance is split into two parts: the cab at the front and the exposed chassis at the rear.

 

At the front, the cab stands out thanks to its yellow color, while the rest is entirely black. The cab was not easy to build, since the real model features many surfaces lying in different planes (doors and rear cab pillars, top of the hood and sides for example), as well as curves that are very difficult to reproduce at this scale, such as the roof. A panel with a curvature over one stud gave a result that was too thin, while two studs resulted in something too thick. I chose to simplify certain lines to ensure a smooth appearance, while staying as close as possible to the original design.

 

The shape of the hood was made possible thanks to the new angle connectors #7. They allow for a simple, clean build and a faithful result.

 

The rear section came together more naturally. It was “just” a matter of building the chassis cleanly, adding the rear winch, building the arm, and adding the toolboxes and the roll bar. This required a significant amount of optimization. After all, it was necessary to fit:

• The rear suspension
• The steering mode selection mechanism
• The rear chassis winch
• The arm
• The toolboxes

All of this in a very limited space.

 

 

Suspension

 

What would an off-road recovery truck be without a good suspension?  I reproduced the original suspension as faithfully as possible. It consists of suspended axles held by links, forming two opposing trapezoids at different heights.

The suspension is responsive and allows for nice axle articulation, achieved solely by the weight of the vehicle - there’s no need to press down on the cab to compress the shock absorbers.

 

 

Opening parts

The following elements can be opened:

• Doors
• Hood (left and right sides)
• Toolboxes

 

 

The toolboxes are built using studful parts and are attached to the chassis with pins and an axle.

 

The doors do not have stops in the open position, so they can be opened until they touch the front wheels. I chose not to add any in order to keep the build simple and part-efficient, and I felt it matched well with the rugged style of the vehicle.

 

 

All-wheel drive and fake engine

 

Just like the real truck, my MOC features all-wheel drive, without a central differential, driving a fake V8 engine. The engine doesn’t spin very fast, partly by design choice. Indeed, the motion is transmitted through the differentials with a 22t/14t gear pair, then from the central axle the motion goes up to the engine via a 12t/20t idler/12t gear train, and finally two 8t gears. I could have added gearing, but it would have made the build less clean and more artificial. As with the door opening, I preferred simplicity.

 

 

Winches and arm

 

There are no fewer than… five winches on this model! Two of them are located at the front and rear of the chassis, to get out of difficult situations or tow a vehicle. These are mounted on a friction pin and are controlled by pulling the rope and using a gear. The choice of a friction pin was made to save space and to offer a different holding technology compared to the other winches.

 

The other three are used for the arm. In all cases, they feature a ratchet allowing the rope to be held without any slipping.

One of them controls the raising and lowering of the arm via the same pulley system as the real truck. The arm’s range of motion is slightly under 90°, with the upper limit being vertical, which can prevent the arm from falling back down.

 

The last two control the towing cables. Their construction is light but sufficiently robust.

 

3-mode steering

Alright, enough with the small classic functions, now we’re getting to the core of the model. What it was built around.

As I mentioned at the beginning, I wanted steering behavior similar to that of the Claas Xerion #42054. But I couldn’t simply reuse the mechanism from this set, since my MOC features suspended axles, which requires steering to be controlled by a rotating axle rather than linkages. With linkages, the suspension would have influenced the steering. To counter that problem, it would have been necessary to add a translation/rotation conversion mechanism, which would have been a real mess.  (Actually, using linkages wouldn’t be impossible with the right geometry, but it would add complexity and likely reduce reliability.)

I based my design on a very simple principle that has existed for centuries: bevel gear transmissions. You’ve probably noticed that when the crown gear of a differential is placed on the left or right, the bevel gear connected to it will not rotate in the same direction for a given wheel rotation. That’s why, on chassis with multiple driven axles, the differentials don’t all have the same orientation.

That’s what I needed: a mechanism with a bevel gear transmission, capable of reversing the direction of engagement - but using knobs to avoid losing wheel alignment. So I came up with this:

 

Steering is controlled by the vertical axle. This axle is directly connected to the front wheels. The different steering modes are achieved by swapping, or not, or disconnecting, the rear axle steering shaft relative to the front axle - just like the Claas Xerion.

• When the grey knob on the carriage is up, it engages with the upper knob of the vertical axle. The front and rear steering axles rotate in the same direction: this is crab steering
• When the grey knob is down, it engages with the lower knob of the vertical axle. The rear steering axle rotates in the opposite direction to the front axle: this is 4-wheel steering
• When the grey knob is centered, it is disengaged: the rear axle is disconnected. However, this introduces an extra difficulty compared to the Claas Xerion: the linkage system naturally locks the rear axle on the Xerion, which is not the case with my system. So I added an automatic locking mechanism. When the carriage is in the central position, locks block the carriage knob. When the carriage is moved, the locks spread apart thanks to rollers pushed by slopes located on the carriage.

The selection lever rotates almost effortlessly, but it can sometimes be a bit hard to grab since it is close to the toolbox. Just like on the Claas Xerion, the wheels need to be straight for the change to occur - within a certain tolerance. Since for each axle the steering shafts rotate slightly less than 90° in each direction (thanks to stops), you can’t, for example, switch steering modes when the truck has its wheels turned to the right in crab mode and end up in front-wheel steering while the rear axle is locked to the right. Well, it is possible - but you really have to want it and perfectly align everything while forcing against the stops.

Front-wheel steering:

 

Crab steering:

 

4-wheel steering:

 

The selection lever rotates a cam fitted with a roller. This roller raises or lowers the sliding carriage of the moving knob. Position holding is ensured by the rubber band located at the front, which presses the rollers rollers against the slopes of the carriage. The carriage/slopes/elastic/rollers assembly naturally tends to return the carriage to the central position. For the upper and lower positions, a toggle point prevents the carriage from returning to center, enabled by a green connector located near the rear suspension - the travel is not ±90° but slightly more.

 

Using a long CV joint makes it possible to compensate for the change in distance between the carriage knob and the rear axle steering shaft when the carriage moves, in addition to suspension travel.

And that’s it - you know everything now! 

 

 

Build and instructions

I did a significant amount of optimization work to achieve a build that is both elegant and enjoyable. I wanted to create a model that would stand out from most MOCs, which often feature poorly optimized construction and an unpleasant building experience. The construction is done through small assemblies that are attached to the main structure, as LEGO usually does. I reworked each sub-assembly until the build felt "obvious" and intelligently designed. (Well, I hope that’s the impression you get! )

The instructions came naturally thanks to the work done during the build process. I wanted them to be more “challenging” than current LEGO instructions, while avoiding all the pitfalls encountered with alternative brands. Concretely, I made sure that all parts in a step are clearly visible so none are missed, avoided (except in rare cases) mixing callouts and parts added directly in the same step, optimized the build order to avoid rotation steps, or prevented issues where a previous sub-assembly blocks progress, for example.

Everything else came naturally during the build, and I didn’t have to do anything at the instruction stage regarding build contrast (use of colors), assemblies that don’t fit properly, etc. The goal was to make the build more stimulating by avoiding chains of single-part steps, without the difficulty coming from poor instructions. Basically, it’s a rally with a good co-driver, not an orienteering race with a bad map. It’s not perfect though - there are, for example, a few assemblies where I prioritized aesthetics over strength, such as the studful parts around the front and rear winches. But it’s the best I could do for now.

 

Result: a MOC with only 1211 parts, featuring:

• 5 winches
• 3-mode steering
• Suspension
• All-wheel drive with fake engine
• Opening parts

For reference, 1:10 scale sets usually range from 1500 to 1700 parts.

 

 

Building instructions: Rebrickable

Stickers: send a request to Forwartsticker

Parts: (coming soon, on MOCBoxing)

 

 

Video

 

All photos can be found here: https://www.flickr.com/photos/162173007@N06/albums/72177720331182416/with/55013628563

That’s it for this truck. I hope you like it!

 

 

Edited Friday at 09:24 AM by Anto
Links for instructions and stickers added

[gyenesvi]

Oh man.. this is a truck I have been thinking of building ever since Matt built it (probably larger scale, RC), but I haven't yet gotten into it. But YOU DID JUSTICE TO THIS THING!

Amazing work, all over the place! A ton of mechanical complexity and ingenuity squeezed in there (advantage of a manual model), in a beautiful packaging. Hats off!

I don't often buy building instructions, but I'll definitely build this one!

[Zerobricks]

So much functionality in such tight package! How do you keep the rear steering centered when only front steering is engaged? Is there a lock? I will feature this model in the near future!

[Aleh]

Very accurate MOC! Appreciate all these functions, especislly different steering modes!

[JunkstyleGio]

That is brilliant! So many functions in a limited space. 

[Stereo]

Now it just needs a Banana for scale!

[N1K0L4]

I'm very glad you came back to building, and what a model to do it with! Just a amazing model packed with features. I like it a lot :)

[Anto]

Thank you everyone for the comments! 

 

22 hours ago, gyenesvi said:

I don't often buy building instructions, but I'll definitely build this one!

You won't be disappointed! 

 

21 hours ago, Zerobricks said:

How do you keep the rear steering centered when only front steering is engaged? Is there a lock?

Yes, like you can see on the 3D and in the video! Red connectors press on the knob connected to the rear steering axle when the steering is in front wheels-steering mode, and disengage when the other modes are selected.

I think it wouldn't be hard to replace the steering mechanism by elecric motors and a BuWizz. But I don't know if I'll work on it or come backto an old project...

 

13 hours ago, Stereo said:

Now it just needs a Banana for scale!

And an apple to scale the banana! 

 

3 hours ago, N1K0L4 said:

I'm very glad you came back to building

Actually I never really stopped, but some models from the past few years can't be made public - for the moment.

[TLCB]

Featured at

The Lego Car Blog

[StudWorks]

I had JUST seen this truck on a recent VINWiki video! Can't wait for the instructions to release, the genius functional Technic bits in this MOC (that LEGO has long parted ways with) are absolutely beautiful!

[TexasEngineer454]

As someone who watches Matt's YT channel quite a bit, you did an amazing job!

I have been trying to build a scaled RC model of the Wrecker for about 6 months. Unfortunately, fitting the various functions (winches, front/rear steer, boom, etc.) has been more difficult than I had anticipated. 

[Jeroen Ottens]

Great MOC! Your solution for the steeringmodes is genius. It is so compact.

colourblocking and design elegance is on such a high level as well 

[thekoRngear]

With Anto's Heavy Wrecker Masterpiece, 2026 has started to bang hard with the MOC world already!

[LEGO Train 12 Volts]

Amazing truck and beautiful explanatory photos...impressive suspension system! 

[Anto]

Thank you for the post on your website The Lego Car Blog! 

 

On 1/20/2026 at 2:51 PM, StudWorks said:

Can't wait for the instructions to release, the genius functional Technic bits in this MOC (that LEGO has long parted ways with) are absolutely beautiful!

Thanks! The instructions should come in the next few days, it's just a little longer than expected!

 

12 hours ago, LEGO Train 12 Volts said:

Amazing truck and beautiful explanatory photos...impressive suspension system! 

I'm happy that you like the renders! I had this idea to make the mechanisms interesting to people who wouldn't necessarily take a deeper look into it.

 

Thanks to everyone else for the kind comments! 

[Anto]

The instructions are available here! For the stickers, you must send a request to Forwartsticker. I will probably make a mini building instructions for the steering mechanism only, it may inspire some of you for new MOCs!

[gyenesvi]

@Anto I'm experimenting with your steering rack linkage on the axles for a build that would have axles of the same width, and it seems to me that the 13L steering rack is scratching the tires even at a fairly moderate steering angle. Is that so on your build? Is the rack scratching the tires? Or is the steering angle fairly limited on this truck?

[Anto]

When I designed the axles, I took into consideration:

• Stops so the axle rotates less than 90° each side
• Stops so the CV joints work fine with the wheel hubs - if the angle becomes too important, the rotation of the wheels is not smooth

This way, I had everything working. However, the tires slightly rub against the gear rack, like you experienced, despite the stop when you fully steer. I don’t know how you took the stop into account (the 1x1 bricks with cross hole) - it can limit the effect but won’t make it totally disappear. 

[gyenesvi]

18 hours ago, Anto said:

This way, I had everything working. However, the tires slightly rub against the gear rack, like you experienced, despite the stop when you fully steer. I don’t know how you took the stop into account (the 1x1 bricks with cross hole) - it can limit the effect but won’t make it totally disappear. 

Yes, I took the 1x1 brick stop into account and the CV joint max angle as well, but in my experience the tire starts rubbing significantly earlier than these limits are reached (when steered about halfway to the stopper limit), this is why I am asking, it seems too early to be acceptable. It may be okayish for manual use (although I can already imagine it to cause enough friction to be felt, don't you feel it when you push the model around?), however, if I build an RC model with this approach, it will soon ruin the tire I'm afraid, especially as I'd want to use it with a higher steering angle (large CV joints).