Western Star 6900 TwinSteer

A Western Star 6900 Twinsteer made in Lego Technic. Remote controlled using Control+ and PoweredUp App for the drive, steering and winch. Tandem bogies suspensions with oscillating arm, removable hood with fake working engine, and openable doors complete the model, as well as a mud pump as the load. With Building instructions.


Direct purchase of the instructions

10.00€ – Add to cart - PDF Excluding 20% tax

Also includes in the purchase :

  • Building instructions in PDF for the Mup Pump (79 pages / 22mo)
  • PoweredUp App Tutorial for the Western Star 6900 TwinSteer (23 pages / 6mo)

Rebrickable partlist (Truck/1511 parts and Mud Pump/854 parts). Preview of the instructions at the end of the article. Presentation Video (YouTube). Ensure you your smartphone is compatible with the Lego app “PoweredUp App”.


I am a huge fan of Snowrunner, a game where you drive big truck into snow and mud, and I especially like the Western Star 6900 TwinSteer, because of its crazy size and its abilities to carry a lot of things, so I wanted to reproduce it Lego Technic. Here is the result.


I have documented a lot the design process on this creation, which includes how I have started the project, choosing the scale, the functions, making the chassis and the bodywork with some tips and tricks. I have presented this design process into two videos, one on the chassis, and one on the bodywork. These videos are English spoken with subtitles. You can watch them below, or skip directly to the final result in the ‘video and picture section’.


  • Western Star 6900 Twinsteer in Lego Technic : Scale 1/20
  • Dimensions : 48.5cm (L) x 12.6cm (W) x 17.5cm (H) 
  • Weight : 1.4kg
  • 1511 parts (truck), 584 parts (Mudpump)
  • Remote controlled using Control+ Hub and PoweredUp App (Lego) (also compatible with Power Functions systems)
  • Drive : 2 L motor with 12/24, 12/20, 20/28 (differential), 8×4 no locking differential
  • Steering : L motor which drives both axle with different turning radius made using variable connecting rod
  • Winch : L motor with worm gearing
  • Suspensions : Tandem bogies with oscillating arms
  • Removal hood with fake working inline 6 diesel engine
  • Openable doors
  • Diesel Mud Pump in container style with optional motorization (free instructions)


Building the chassis

This video presents the beginning of the project and how I build the chassis with the drivetrain, suspensions and steering :


Building the bodywork

This video presents how I design the bodywork, with different approach and some building tips and tricks :


Final result (Pictures and Video)

This video presents the final result with all the functions and outdoor testing :


Purchasing the creations or the instructions

The Western Star 6900 Twinsteer is proposed for sale at Buildamoc in a complete package which includes the Lego genuine parts (control+ hub option) and the building instructions in a PDF (with or without the Diesel Mud Pump). You can only purchased the instructions if you want on my website (see building instruction section below). Please ensure you first that you smarpthone is compatible with this app (available for Android and iOS).

buildamoclogoWant to buy this creation ? The Western Star 6900 Twinsteer has been indexed to Buildamoc and is for sale. The whole package included the Lego genuine parts and the Pro rendering PDF building instructions (with or without mud pump).

Building Instructions

The instructions are 221 pages, step by step high resolution computer generated instructions with partlist, color coded cable with layout, flexible parts, in the same way as official Lego one. It also includes 23 pages step by step tutorial in PDF to configurate the model for PoweredUp App (available for Android and iOS). Please ensure you first that you smarpthone is compatible with this app.

Regarding the bill of material, they are includes in the instructions and you can watch in the instructions preview below, but you can also checked the exact bill of material on Rebrickable and export in whatever format you want :

Want to know if you can build the Western Star 6900 TwinSteer ? The model has been indexed to rebrickable, check it !

You can buy the instructions with the following button for 10€ excluding tax. 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). The automated discount is available for all the instructions for sale on nico71.fr.

Western Star 6900 Lego Technic + Mud Pump (free)

Mud Pump only (free)

(rebrickable Bill of Material for the Mud Pump)

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 48h. 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 :

(2) Comments

  1. Avatar photo

    An other nice model! I like the way how you explain the differents choices you made to make it.

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