Rally Car Transformer

A motorized rally car transformer which transforms from a car to a robot. With building instructions.


Direct purchase of the instructions

Rally Car Transformer
7,50  -Excl. Tax
A LEGO Technic motorized rally car transformer which transforms from a car to a robot, with complex gearing and linkage mechanism.

Preview of the instructions at the end of the article. Presentation Video (YouTube).


I must admit that I am not a huge fan of Transformers movie and robot fight, but I like mechanism and wanted for a while to build a real car which can transform into a transformer robot with not only the chest and head to move like a toy but all the body, including the feet, legs, chest, head, arms and so on. Then, I decide some months ago to start this creation by seeing the work of barebos on youtube who have made a prototype. I have made many prototypes to have the correct dimensions and proportions for the robot and then design (or trying to design) the car. Here is the final result.


This model has only one function, which is the purpose to what it has been designed (of course you can play with it but there is no steering). This function is the most important and takes the whole space in the model. It is basically composed of  :

  • A M-motor which drives the whole system (in red and yellow)
  • Articulated feet lever which deploy the feet under the bodywork (in blue)
  • A double linkage lever to maintain the chest of the transformer to be parallel to the feet lever (in pink)
  • A third linkage which connects the double linkage to the front, in order to reveal the head (in green)
  • The two arms attached to the chest which are moved by a last system of linkage (non represented here)

The M-motor drives two system of worm gear. The first drive train powers the pink linkage. This linkage is attached to the blue feet lever which is powered by the second worm gear thanks to the T shaped parts. This configuration with the two worm gears and the double linkage enables to have the chest (basically in red on the picture) to be parallel to the blue feet levers. Thanks to that, the feet can be folded in the chassis like a accordion and takes the maximum available space to gives a nice proportioned robot which raises from the ground.

The blue feet levers are necessary to lift the whole transformer by pushing on the ground and to be a part of the feet at the end to avoid falling, the feet touch consequently the ground as soon as the lever start to rotate. Then, the double linkage is connected to the front of bodywork, and the length between pivot point allow a 90° rotation of the front bumper when the whole linkage made a 180° rotation. Like that the transformer can raise from the ground and reveal the head of the transformer by rotating the front bodywork. you can see in fact that the head is hidden inside the front bodywork but is attached to the chest.

To finish the arms of the transformer are attached to the chest and are composed of a double linkage system, which makes rotate and move on the side each arm. Each arm is connected to the first double linkage (in pink on the picture) with 6L link. Therefore the doors of the car is the arm of the transformer and the hands are hidden at the back.



At the beginning I wanted to have the battery box in the model, but I had to remove it because of the weight and that I have not enough place to put a big motor. Even with a big creation to have enough space to put two big motors, the weight was too important to lift the transformer (do not forget that this is the feet which lift the transformer). Therefore I decided to choose small scale to have a small weight and tiny motor, of course the battery box would not be in the creation but apart and connected with a wire.

The main consequence of this was the design of the bodywork. When I have finished the mechanism of the transformer, I was able to start the bodywork, but due to the scale, I could only make a design which was a compact rally car. It could not have a trunk (or maybe with a more complex linkage), and the wheel base was small regarding the scale, because I focused myself to have a correct proportioned robot regarding the feet, legs, chest and arms. Regarding the doors, they are also the arms with the hands, therefore, the hands in black are hidden at the back which is simple and handy, which would be not the case if I chose a different design. This is the same reason why there is a gap between the rear light and the roof, because when the transformer is raising, I have to have enough space to handle the displacement of the roof.

The head is also hidden in the hood, which affects the design of the head. I was limited in width but think that I found an interesting combination with black connector to create the mouth and face, plus some white parts, especially the cheese slope which makes the nose.
To conclude, this type creation was the first I did, having a car which can transform into a robot. It was very interesting to works to the mechanism especially the complex system of linkage, worm screw, lever, moving and non-moving parts which makes a good working creation. The building is very compact to keep a small scale in order the robot can be raised by a motor, therefore there is not many space to create detailed interior, fake engine, steering, or drive train. The design was also a consequence of that which is not bad (rather cool I think), but maybe a lack of crazy color and shape which can be seen on original Transformers movie. As I said, I not very good in designing manga things.

Pictures and Video

Purchasing the creations or the instructions

You can purchase either the whole creation on the website Buildamoc, or just the building instructions.

buildamoclogoWant to buy this creation ? The Rally Car Transformer has been indexed to Buildamoc and is for sale. The whole package included the Lego genuine parts, and the Pro rendering PDF building instructions.


Building Instructions


At the beginning of this moc, I wanted to make a building instructions because when I searched this type of creation, I did not find with instructions. I tried to make it with photo sequence but it was a total mess. Therefore I decided to create a pro-rendering instructions for sale, at 7.5€, which enables you to rebuilt it, step by step, part by part.

Here is the complete bill of material in picture file :


But you can also checked it on rebrickable :

Want to know if you can build the Rally Car Transformer ? The Rally Car Transformer has been indexed to rebrickable, check it !

You can buy the instructions with the following button for 7.5€. You can also buy other building instructions and get an automated discount. You will get 15% off for 2 PDF, and 20% off for 3 PDF on the total), available for all the instructions for sale on nico71.fr.

See it on the shop :

Rally Car Transformer
7,50  -Excl. Tax
A LEGO Technic motorized rally car transformer which transforms from a car to a robot, with complex gearing and linkage mechanism.

After your payment, you will be redirected to a page for downloading your instructions, and will receive also the link to download by email. Please check the spam box and be patient to receive it. If you have trouble to download your copy of the PDF after payment or open the document, do not make a paypal dispute, please contact me using the contact form. The link to download the instructions expires within 24h. Contact me if you have lost your instructions. Note that you can print it, but not copy or distribute. Thank you for supporting my work 🙂

Here is some preview of the building instructions :