Decoding the gearbox of the LEGO Technic 42110 Land Rover Defender

After my review of the LEGO Technic 42110 Land Rover Defender I received a lot of questions about the gearbox, how it works, does it really runs inverted, did I make any building mistakes etc. I decided to create another video to show the gearbox in details, demonstrate why I think it runs the other way around and give anyone a chance to take a closer look
at my build and find any possible errors.

Besides the video demonstration here’s a little written summary about the drivetrain of the Defender.

In a normal car the engine drives the wheels through the gearbox, in a LEGO car this is the other way around. By pushing the car the wheels are driving the fake engine through the gearbox.

If we take a look at the bottom of the car we can see that both axles have a differential and the wheels are driving a central differential. There’s a 8T/24T gearing on both axles, which means the speed of the wheels is significantly slowed down.

The power from the central differential is transmitted to the DNR selector through a series of gears.

If the DNR selector is in drive mode then the power is transferred to the right side of the vehicle to the hi/lo selector.

Here you can see that low mode the power coming from the wheels is again geared down. This is incorrect, as it will make the fake engine run slower. In a real car at a constant wheel speed a lower gear means a faster engine.

After the hi/lo selector the power is transmitted to the gearbox through an axle and it comes back on the other one.

And at the end it reaches the fake engine through a series of gears in the front.



  1. Hi,
    First of all, thank you for sharing this information. I learnt a lot. Too bad I didn’t check your videos before building mine. As now I see my rear wheels are moving in the opposite directions, making the Defender not able to move at all. Just wondering, is there an easy way to fix that without pulling apart the whole thing? Just can’t fathom spending another weekend making it again :(.

    Cheers and great work!

    • I guess you have the differential reversed. Don’t think you need to take it apart completely, you need to be able to disconnect the steering arms holding the hubs to pull out the axles from the differential. There are a couple of things to remove for this operation but should not be too difficult.

      • Would you please explain this in more detail? I have the same issue as the commenter above. And it seems like other people are having the same problem as well, as I also saw people mentioning it on Reddit and Facebook. The front and back wheels are moving in opposite direction.

        • If you check steps 4 and 134, you need to make sure that the orientation of the dark bluish gray piece (the differential) is the same as on the picture and not turned by 180 degrees.

  2. I just turned the rear differential 180 degrees. Was a bit of fiddling – but I am currently starting fase 3, so I was relieved to find that it was not that much deconstruction. Carefully remove the lower wishbone and you are able to reach the diff. Don’t drop the small parts into your model. I did. Was nerve wrecking shake but I retrieved it and was able to remove and rebuild the whole thing within 15 minutes. Good luck!

  3. Anyone had an issue with the wrong size gear wheel on page 28. First instruction it shows grey 24 teeth it’s too big. Beige gear seems to be the correct size.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.