Oct 17 2010

Motorized Off-Roader (#8297)

Category: Lego,MindstormsSpiller @ 15:35

This project was an attempt to combine the Lego Technic Off-Roader (#8297) and Lego Mindstorms NXT kit and thus motorizing the functions.

To summarize the project it ended up having these features:

  • NXT controlled steering
  • NXT controlled rear wheel drive
  • NXT controlled suspension height
  • PF motorized winch and lights (on-board PF power box)
  • 2 step manual transition
  • All original features (V8 engine, doors and such)
  • Almost no changes to the visual design

The electronics used:

  • NXT microcomputer
  • 3 NXT motors
  • PF power box
  • 1 small PF motor
  • 1 PF switch
  • 1 pair of PF lights

I ended up getting bored and stopped working on it so there is still some rough edges, but in general I’m pretty satisfied the result.

The following text is an old description of the project I found on my HDD:


First step was to remove the designed parts carefully and making notice of where they were connected to the chassis in order to add it later when the NXT is added.

The original model has one motor connected to two functions by a manual gear switch. Since this wouldn’t work with a NXT, all the mechanics had to be changed.

Therefore, everything else than the fundamental chassis was ripped out.

Later on, some parts of the chassis was also changed to fit everything together.


The Power functions was preserved. The small motor was placed in the very front, directly connected to the winch. The battery box is also placed in the front together with the electrical switch.

In the back where the battery box had been, the NXT is placed with two NXT motors underneath. The last NXT motor is placed under the seats.

A manual 2 speed transmission was added in the bottom. The original differential was replaced with the older type differential because the new one isn’t strong enough and the gears would slip under the pressure.

Final product

There where almost no changes to the original design, so it looks very much like the original model other than the NXT parts which are visible.

I got bored in the end and finished the construction a bit too fast and didn’t fix the 2 step transmission. It sometimes under huge pressure jump out of gear. It should be easily fixed with a rubberband or something similar which can hold it in place.

18 Responses to “Motorized Off-Roader (#8297)”

  1. Rastwo says:

    Which NXT set have you used? i want to make something like that too. I have 8297 (off roader 2) and NXt 2.0

    • Spiller says:

      I just used the parts I had in my collection, so no specific sets where used (except for the 8297 of course). Just try to incorporate the NXT 2.0 with the parts you have.
      If you want an easy solution, check YouTube, there are quite a few videos that shows how to configure the set with wireless PF. Not all of them are completely purist as the differential used in the set is quite weak and can’t handle the force needed to drive it. (I replaced the differential with an older type that is stronger, but this is a bit more work.)

      • Rastwo says:

        and please,have you made any LDD or instructions? i really want to do it.i have tried two times to build it,but i have not done it good(like you).
        But, I think that this do not need differential, this can work without it.Thanks

      • Rastwo says:

        and now you have? please can you do that? i think that much people want it.,not only me. I am still thinking how to do it,but I have no idea. if you will do it, you will be better like Sariel. Thanks :)

      • Spiller says:

        No, I don’t. And secondly, it would be impossible to do it without the model which I took apart long time ago…

      • Rastwo says:

        so nothing. But,if youmake it please send me it to rastwo@centrum.sk Thanks

  2. fabio says:

    pleeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeease send the building instructions to me.thanks

  3. Rastwo says:

    And can you please write which motor do what? It will be helpful when building.

    • Spiller says:

      Two NXT motors are positioned in the back, side by side. One of them provides power to the back wheels and the other controls the height of the suspension.
      The NXT motor under the seats controls the steering.
      Underneath the V8 there is a small PF motor which is connected to the winch. Underneath this motor is the PF battery box.
      The position of the NXT is quite easy to spot.

  4. taz says:

    Very awesome. You wouldn’t happen to have the building instructions in a ldd file or something and also the .rbt that the NXT uses? If not, building instructions at least some good close-up pictures and the .rbt because sometimes creating the NXT program can be a challenge all by itself. thanks!

    • Spiller says:

      I started on a ldr file (LDraw) but I didn’t get very far with it…
      I didn’t make a program to it, it is remotely controlled. It would have been fun to make a remote using a second NXT, but sadly I didn’t have one… It would have been programmed in NXC though. (I only use 3rd party tools at the moment, because they are simply better than Lego’s own.)

      I will try to dig up some old stuff to improve this post. Don’t expect much photo-wise though, other than full-resolution versions. I will try to get it done in a week, so check this post again later.

  5. Rastwo says:

    And have you got any photo of differential?

    • Spiller says:

      I do not. I threw out the differential and used one of the old 4 studs wide differentials. The gearing of the new diff is simply too weak.
      There however isn’t room for a 4 stud wide diff so I had to change the construction to make this possible.

      Also, notice the beams that are positioned below the diff, connecting the two sides of the car. When the additional motors and NXT is added the weight increased. Without those beams the extra weight would tear apart the suspension (when doing drop tests).

  6. Legoer says:

    Your work is very very good ,is fantastic but can you sent photos of your Lego nxt of roader , but from the other side.This is my email :chrislocomondo@gmail.com
    Thank you!

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