Lego Tumbler

When Christopher Nolan decided to shoot a new Batman film in 2005, one of the most iconic components of the design was the Batmobile.  Over the years it’s been seen in all sorts of guises, and by today’s standards most have been cheesy and unbelievable.  The ‘Tumbler’ was different, having a back-story of its own, and was quite simply awesome.  Of course, it came with its own technical difficulties to overcome, most notably at the front wheels.  With no conventional axle to hold the wheels in place and provide steering, everything had to be reversed and miniaturised, whilst keeping it rugged enough to stand up to the rough treatment of jumping over things.  By all accounts the Tumbler was a fantastic machine, both in looks and performance.

Tumbler completeOne might think, then, that such technical achievements would not be possible on a smaller scale.  Think again.  Having reclaimed my Lego a couple of weekends ago, I set about creating my own Tumbler.  I had seen on another web site that other people had had the same idea, creating some stunning reconstructions of the iconic vehicle.  But almost all had static front wheels, providing no steering, and only a few sported suspension.  True, it’s no easy task, and it took a lot of thinking and experimenting to get it right.  But I did it, and I am pleased to reveal images of my very own working model of the Tumbler, completely constructed of Lego.

Technically, the steering mechanism is by the most complicated part of the car.  Or should that be tank?  Whatever.  Each front wheel has its own steering mechanism, comprised of a transverse rack-and-pinion system linked up to a custom wheel bearing joint.  You can see a little of the mechanism in the photo below.  Not only do you have hardly any room in which to put all that mechanism, but it also has to be solid enough to support the weight of the rest of the vehicle.  With the offset of the wheel and the looseness in the bearing I actually had a problem with the camber of the wheels.  To resolve that I had to put some spacing at the top, effectively angling the whole wheel downwards to counteract the camber.

Alongside the complications of steering, the suspension system used in the Tumbler is quite unusual.  The wheel sits at the end of an arm, which pivots at its connection with the rest of the subframe, and it held in place by two small springs for extra rigidity.  The placement of those springs actually means a lot of spring force is needed, hence two springs on each arm rather than two; it’s all to do with turning forces and suchlike – the springs would have been more effective at a different angle, but then they wouldn’t look right.  Thankfully they just about do the job ok.

At the rear end I’m using a couple of enormous wheels.  The original Tumbler had two sets on each side, but since I didn’t have four wheels that size, and my big ones roughly equated to the same total size, I settled with those.  Those wheels on their own account for a fair proportion of the total weight of the car.  Again, independent suspension has been used, so that each wheel has its own springs, giving the car a stable feel in the corners.

The original Tumbler had a jet boost thingum at the back, between the rear wheels, which launched it across rivers (in theory).  Since I don’t have a Lego Jet Pack, I used that as a steering wheel, linking it to the mechanism at the front of the car.  I find that a more comfortable place to put steering mechanisms on Lego Technic models anyway, as it allows you to push and steer at the same time, more effectively than having the steering controlled from something on top of the car, as is preferred by the official Lego models.

The working chassis was brilliant.  It was light, agile, sturdy, and handled jumps and rough treatment with hardly a complaint.  I’ve put a video on YouTube demonstration some of the features.  Unfortunately, the bodywork that was added later made it all rather heavy, putting a greater strain on the suspension and in some cases hampering performance.  It certainly looks better than a bare chassis, but drop it too heavily and it’ll collide with the floor.  If I was building it again, I’d definitely make the suspension harder to compensate for the bodywork.  The front suspension particularly feels very soft now, and while it handles the occasional bump fine I wouldn’t want to be leaping it over ramps now!

It’s not perfect, but any means, but it’s not bad as a first attempt at a model on this scale.  The bodywork isn’t quite right, partly due to the limitations of the chassis itself and partly a lack of black panels!  I’m also not entirely satisfied with the steering mechanism.  Impressive as it is, I’m sure there is room for improvement.  I already have ideas for more streamlined versions, which would allow the arms to be lighter and thinner, but it’s a case of balancing that against maintaining rigidity and strength.  I would also redesign the central chassis to make it more structurally rigid and less likely to fall apart (at the moment the main part of the chassis is fine, but everything on the outside has very little to hold on to).  It would also be nice to put an engine in the back and link it to the rear wheels, but I expect that would need a fixed rear axle rather than the current setup.

Will I do another Tumbler?  Probably not for a while, if ever.  The only reason I was able to spend so long on this in the first place was because work wasn’t too busy, and Ellie was out at work all day and didn’t mind the lounge being taken over by my Lego.  Now that she’s back in her normal routine she’ll be back a little more often, so the Lego will probably go back in the garage until I can think up another excuse to play with it again.  The Tumbler will stay built though, and may even stay on display downstairs if I can find a space for it (doubtful, but you never know).

Pics of the bare chassis:

Tumbler chassisTumbler steering

Pics of the finished model:

Finished TumblerRear suspensionFront suspensionTumbler front

Accompanying YouTube videos:

11 thoughts on “Lego Tumbler

  1. That’s VERY impressive. All that childhood training wasn’t wasted after all. If only you could convert that Lego expertise in to income…

  2. I’m really impressed… I tried to make a tumbler with MINDSTORMS, but it wouldn’t work. The only thing that you could improve (to my oppinion) is by making the outfit with LEGO Technic, for better angles.

  3. how do the wheels turn. i understand the rack and pinion system but there aren’t enough pics of the tie rods turning the wheel bearings for me to wrap my head around that.

  4. The steering is a bit of a nightmare, and I couldn’t take any good photos of the mechanism so I’m not sure how best to explain it. Maybe I’ll have to draw up a schematic diagram or something at some point. I still plan on taking it all apart and making a better version at some point, so maybe then I’ll put up more details on how the steering works!

    Glad to see people are still finding this post and commenting, it’s pretty old now… 🙂

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  6. WOW!, first off. This is amazing work. I’m really impressed by the steering.

    I’m working on something similar: a Lego ThunderTank. I hope you won’t mind me using your Tumbler as inspiration for the internal mechanics.
    And any advice you can provide would be great.

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  8. me and my little brother tried to make a tumbler i had the same idea with rack and pinion steering i got the rig built now i cant figure out how to attatch it and my frame sux any advice you have would be great

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