Steering idea for LEGO 76023 UCS TUMBLER

[Zerobricks]

Here's my attempt to add steering to the awesome UCS tumbler:

[jorgeopesi]

Good idea Tumbler maker .

[S.I]

Nice idea. I hope that doesn't result in too much torque being applied to the remaining fixed connection.

[nikolyakov]

I think, back of the tire will touch the chassis.

[Rishab N]

That looks interesting. Looking forward to seeing it on the real thing

[Blakbird]

Having just built the Tumbler, I can tell you that this solution won't work. The problem is that the tire is much wider than the wheel and is already touching the support arm. In order to add even a little bit of steering, you'd have to move the whole wheel inboard one stud. To get a good steering lock, you'd have to move more than that which would throw off the scale of the model. To keep the wheels where they are, you'd have to change the support arm to be only one stud thick instead of two which would be too weak in torsion to support the weight.

[Paul Boratko]

Eric, are those Gold hubs just as wobbly as the LBG ones..?

Our 2 sets are coming tomorrow...

[Rishab N]

Little OT but Shop@Home hasn't been working the entire day for me. Anyone else have the same problem?

[JGW3000]

Rishab, I had the same problem, try logging out and then back in from the main Lego.com page

Edited August 21, 2014 by JGW3000

[Rishab N]

Rishab, I had the same problem, try logging out and then back in from the main Lego.com page

Doesn't work I keep getting lines and lines of code and some sort of "http status 500"

[Lipko]

Having just built the Tumbler, I can tell you that this solution won't work. The problem is that the tire is much wider than the wheel and is already touching the support arm. In order to add even a little bit of steering, you'd have to move the whole wheel inboard one stud. To get a good steering lock, you'd have to move more than that which would throw off the scale of the model. To keep the wheels where they are, you'd have to change the support arm to be only one stud thick instead of two which would be too weak in torsion to support the weight.

That's why I said in the Tumbler thread that increasing size actually makes incorporating steering harder than easier. Sariel's solution is the best I've seen so far, and it still looks a bit off. I'm struggling with this problem for a while now, built many versions, maybe I will have to give up the project.

Edited August 21, 2014 by Lipko

[Zerobricks]

Too bad it does not work... Well I gave it a try...

[gmshades]

I wonder if there are pictures out there of how the real tumble steers? Maybe that will help in the design for the Lego Tumbler.

[Zerobricks]

The real one uses hydraulic arms to steer the wheels, simillar to my idea...

[gmshades]

I noticed in Jay Leno's video driving the Tumbler, it is similar to your design. However, the steering pivot on the real car is inside the wheel hub. Lego's pivot is outside the wheel. When will Lego fix this?!

[Technyk32231]

I noticed in Jay Leno's video driving the Tumbler, it is similar to your design. However, the steering pivot on the real car is inside the wheel hub. Lego's pivot is outside the wheel. When will Lego fix this?!

Never. Not even the 8448 wheels pivot in the center, and I doubt that Lego would use advanced steering geometry like kingpin inclination or multiple steering links that have an imaginary pivot point.

[Lipko]

I don't think the steering pivot is a huge problem with the Tumler, at least it doesn't have mudguards. Okay, the wheel can't turn as much before hitting the suspension arm.

An exaggerated Ackermann would give decent turning radius while the outer wheel still wouldn't reach the suspension arm.

Edited August 22, 2014 by Lipko

[jovel]

[Lipko]

Jovel, may I "steal" your idea?

[jovel]

@Lipko

Go ahead!

I forgot to mention in my previous post - but I also think it is pretty clear - that if you want to use this system in the Tumbler, you gonna have to completely rebuild the whole front ( and also wil need to make some changes to the styling parts ).

[Zerobricks]

Thats a great solution with a nice virtual pivot point!

[drdesignz]

...the tire is much wider than the wheel and is already touching the support arm.

I just finished building this last night and the tires do not touch to support arm. The gap is about an 1/8" of an inch or so (4mm, I think). Maybe you installed the wheels backwards?

[Paul Boratko]

I just finished building this last night and the tires do not touch to support arm. The gap is about an 1/8" of an inch or so (4mm, I think). Maybe you installed the wheels backwards?

Would it make a difference which way you install them..? I am looking at them now and it seems it wouldn't matter one way or the other as the wheel offset is the same inside of the tire...

What about wobble from the hub...? Does that cause them to rub at all...? I know the play in these hubs is pretty bad...

[drdesignz]

Would it make a difference which way you install them..? I am looking at them now and it seems it wouldn't matter one way or the other as the wheel offset is the same inside of the tire...

I'm not sure... I just removed the wheel and reversed it. The tire is now closer to the support arm, just barely touching with some play in the hub. I thought maybe the offset of the wheel was different, but it looks like it is the same and it's the tire itself that's not perfectly symmetrical. I took pictures. This image shows the wheel installed per the instructions. This one is reversed. You can see a slight difference in the gap.

[unicorn]

Just come up this idea. Not sure if it can really work as I don't get the Tumbler UCS yet. :)

Edited September 5, 2014 by unicorn