Tatra 4×4 T815

My first Trial Truck with 94mm wheels. Features drive, steering, fake engine and independent suspensions with swinging half-axles. Including building instructions.

The aim of this truck was to participated at the contest organized by Freelug at Fana’briques 2010. The main impositions were : powerful, high ground clearance, small turning radius and full independent suspensions. In order to complete the challenge, I have ordered 2 94mm-diameter wheels,then the building process could start. The axle are the most resistant tatra’s axles I have made, because I used this parts to create the bevel gears, reinforced by transverse liftarms to lock the structure. The 94mm-diameter wheels enable to use portal axles with high ground clearance. The final reduction is 12/20, 8/24, 8/24 so 1/15.


In order to have the maximum of stability on slope, I have chosen during the building process that the Battery Box will be in the frame, in the front for 66/33 wheight distribution. As far as I know, the 66/33 weight distribution is very good for clearing abilities with real off-roader vehicles (you can consult this post to understand why). To avoid a complex drive-train to give power on the fake engine, I used a simple drive-shaft as real, built with 2 U-joins. Considering the small place I had near the XL motor, I have chosen to build the U-join with a Ribbed Hose as suggested on the official lego patent.


The steering is operated by a M-motor hidden in the cab, It drives 2 pulley with Rubber Belts, before the 8t/rack pinion. The turning radius is 50cm, that is quite good considering the scale. The real Tatra has a turning radius of 7.5m (15m to 180° turning), with 1/12 scale, the corresponding turning radius I have is 6m, that is really good. To conclude with the clearing abilities, they are really good, much better than my unimog (V2), thanks to the wheels, the ground clearance and the turning radius. The suspensions work great but this type of axles generates a little friction on the bearing axles, that is why it still could be improved. Fortunately, it’s the main purpose of the quest of “holy trial truck”. Nota : on the video the battery box is really tired. You can watch the building instructions here.

Another Youtube’s videos by Legoman104

The building instructions are available. You can watch them by browsing my website or

Download the Zip Archive of the Tatra 4×4’s instructions, 7 mo, ZIP.

Designed in 2010

(33) Comments

    Nico, I realise that this is an old project (6yrs), but could you make a part list for it or an LDD file (the one uploaded in comments doesn’t work) so we could know what parts we miss etc, as I want to do the MOC.

    Hello Nico.
    Nice truck!! How did it perform in the competition?
    By any chance, did the bevel gears slip when the truck had an obstacle? Another thing, does the PF XL motor carry the 94.8 x 44 mm wheels comfortably or would it need to be coupled to an extra motor?

    Hello nico i saw this and i thaught the steering could be remade so im trying hard to build a similar but different steering. =)

    hi nico! my name is autin fretschel. i love to build lego trial trucks but there are no races ina merica. another thing is that i am building a lego tatra. i need some help with the winch and back bed. thanks

    Sorry, no, this steering is accurate and reliable, what we expected of a Trial Truck steering.

    i’m your fun but in this model the sterring don’t function very well can you help me with this problem? thanks

    really tank for this chassis, I don’t used power+functions but I have used rc unit with old 9v motor from the set 8475 and I add another rc motor…now it’s a very beast

    excuse-moi nico, mes es-que ce serais possible que je prend ta cabine de tatra ? je veux en faire une mais je peux pas réussir.

    I was in the process of building this truck and I tested it when the drive and steering where completed and the differentials crack, I use the small universal joints that Lego has made and I added some parts to make the axles more strong. Can you help?

    and good luck whith your next model i hope it goes well and i hope you put instrucs for it.

    right ok but i have never used it in sand,mud or water.
    i guess its just i dont build things good enouth to make them exellant but but i have used it alot and in alot of stress and once overheated so it mussed be that.

    Hello, I don’t think that XL become used after 2 years. Maybe do you have used your motor in agressive environment (dust, rust, sand) ? So you motor should have the same power even if they are two-year old. I hope I have respond correctly. Regards

    hello nicolas but i have a big question when XL motors get old,do they also get weaker? i have had mine for about 2 years now,would it still have the same power as it used to? thanks if you reply correctly.

    I think it is possible. But, I know that the steering is not perfect, les pulleys slip. Regards

    Hi Nico,

    I have just finished this Truck, thanks for the instruction photos! This vechicle looks great, I love the design and the suspension as well. Do you think it’s possible to make the driving system with knob wheels? Because the 12 tooth bevel gears and 20 tooth gears easily slipping in case of high torque.

    Thank you,

    Sorry, I don’t have enought part to sell one copy and keep my own parts. You can go to bricklink.com and purchase all you need, then follow the building instruction and you will have your copy of my tatra ! Regards

    hi, i was wondering if it would be possible to get one built for myself, as i don’t have the access to the types of parts that are need. i don’t need it to be motorized, as its going to be on my work bench and such for display. I’m a huge fan of Tatra’s. I’m willing to pay a reasonable amount if need for parts(including mailing and such)
    thank you.


    I build up this amazing model, great job!
    Have one concern regarding steering, compare to Unimog V3 steering it is too weak and too fast, did you somehow enhance it?
    I will try to reduce the M motor RPM and will see if it work.

    Again Great work and thank you for sharing your ideas.


    If you could make more detailed photos or even building instructions for the basic tatra type chassis that is included in this trucks folder on brickshelf, it would be great

    grüße nico
    gibt es für deinen tatra einen plan würde ihn gerne mal nachbauen
    mfg manuel

    This is a very amazing model I finally got most of mine put together with a few substitutions for some of the lifts arms for the truck my only question is how do you keep the drive pulley for the steering from sliding out of the motor did a few test drives an it keeps slipping out.

    I was wondering if it be possible to give a list of which elements an how many were used in this model.

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