Make Ackermann Great Again!

[Attika]

Hello good people of Eurobricks,

I came out of the depth of my offline existence to share an idea.

First a disclaimer: It is possible that what you see here is not new, I'm just being a lazy person, did not really dig up the internet to find out before I posted the video and wrote this topic.

So as many times, inspiration came from the RC industry, where I discovered a rocker based mechanism being used to create ackermann geometry. The established method which we (I) used to use in our builds (based on wheelhub extension) I find, to put it mildly, flawed.

In my case, I like to build with offset rims (defender and 1:8 supercar ones). Unfortunetelly this combo really limits the options how to apply afformentioned method. Hence I've started to chew that rocker based idea and to my pleasure it has shaped to a presentable concept that might be useful in future builds of ours. 

As one video can say more than a thousand words, let me link it below and if there is any question remains, I'm obliged to discuss it below.

Yours sincerely.

 

 

[jorgeopesi]

Very cool I could spend my all life watching videos like this.

[gyenesvi]

Really nice design and explanation!

[Krxlion]

Glad to see you back. First, video of "Trial Trucktrial", and now some in-depth look of certain topic. It is true that a lot of things we are "borrowing" from RC theme, but it is not like those are getting out of the blue.

Thanks for sharing, and I hope you will keep up with continuity of your effort both on Eurobricks and your YouTube channel!

[Attika]

17 hours ago, jorgeopesi said:

Very cool I could spend my all life watching videos like this.

Not my strongest side, which makes it quite a compliment. Thanks

11 hours ago, Krxlion said:

Glad to see you back. First, video of "Trial Trucktrial", and now some in-depth look of certain topic.

The keyword is the effort. With age, I feel like the treshold what is worthy to manufacture content around is growing. (It's a fancy way to say I'm getting lazier) Anyway, this topic  has reached it, the crawler videos are kinda effortless and the algorithms are punishing me harshly for this stance. Deservedly so, I must say. 

12 hours ago, Krxlion said:

but it is not like those are getting out of the blue.

The front side manadgement is something I'm proud to come up with. (last minute of the video) That gives us a new type of freedom in the application of the geometry.

12 hours ago, Krxlion said:

 I hope you will keep up with continuity of your effort both on Eurobricks and your YouTube channel!

But to keep up the hopes, sometime this week I'll tear down the trial truck in the front of the camera as it has a few tricks up in it's sleeves, allthough it will be more divisive due to my edgy use of our beloved plastic.

[MangaNOID]

21 hours ago, Attika said:

In my case, I like to build with offset rims (defender and 1:8 supercar ones). Unfortunetelly this combo really limits the options how to apply

Perfect situation for this application!

Thanks for sharing. This will come in very useful with in-situ tweaking 

[Stereo]

The Barcode Truck (8479) has a similar method where the rack is moved closer to the axle (so it's 1 stud ahead, the links are 2 studs ahead as standard).  It does mean it uses square root link lengths of √5 (same build as your ellipse parts, 1 x 2 y on the grid) so it probably requires the new 2L link with towball/socket parts to put it on something with suspension.  I don't know why they "discovered" the solution and then ignored it again, maybe space constraints on building a sturdy axle with the rack in that spot.

[Lipko]

Ackermann geometry is the very first thing I usually ditch when building suspensions. Maybe this will change it, thanks!

(adjustability is the second thing, maybe you could come up with something applicable for that too :) )

[Attika]

1 hour ago, Lipko said:

Ackermann geometry is the very first thing I usually ditch when building suspensions. Maybe this will change it, thanks!

 

On 7/29/2025 at 11:39 AM, MangaNOID said:

 This will come in very useful with in-situ tweaking 

I hope to see it in your future builds. :-)

2 hours ago, Lipko said:

(adjustability is the second thing, maybe you could come up with something applicable for that too :) )

If you mean the adjustment to wheelbase, that I refered in the video. using 3x2 rockers gives a more "agressive" ackermann effect, using 4x2 has a milder outcome. So generally the distance between the link and the pivot of the rocker is the key in this question. 

12 hours ago, Stereo said:

The Barcode Truck (8479) has a similar method where the rack is moved closer to the axle (so it's 1 stud ahead, the links are 2 studs ahead as standard).  It does mean it uses square root link lengths of √5 (same build as your ellipse parts, 1 x 2 y on the grid) so it probably requires the new 2L link with towball/socket parts to put it on something with suspension.  I don't know why they "discovered" the solution and then ignored it again, maybe space constraints on building a sturdy axle with the rack in that spot.

I've downloaded and built that mechanism since you posted.

It is a clever way to get the result in that build indeed. Your suggestion to use the new 3x1 socket pieces would make the offset rim usage practically impossible and since the main principal rely on the very specific placement of the rack between the midline of the axle  and the pivotline of the steering link makes it impossible to build an driven front axle at least an elegant one. Beside that it requires fraction of stud lenghts as you rightly pointed out, hence fine tuning it would be a nightmare. Apart from these nuances is very similar. :-)

Thanks for pointing on that solution. I own that set, but I did not remember this specific solution in it. Lego had more purpose oriented solutions for ackermann in the set 8880 and 8865 (if I'm not mistaken on the set number)

[Stereo]

4 hours ago, Attika said:

Your suggestion to use the new 3x1 socket pieces would make the offset rim usage practically impossible and since the main principal rely on the very specific placement of the rack between the midline of the axle  and the pivotline of the steering link makes it impossible to build an driven front axle at least an elegant one. Beside that it requires fraction of stud lenghts as you rightly pointed out, hence fine tuning it would be a nightmare. Apart from these nuances is very similar. :-)

Thanks for pointing on that solution. I own that set, but I did not remember this specific solution in it. Lego had more purpose oriented solutions for ackermann in the set 8880 and 8865 (if I'm not mistaken on the set number)

I don't see where the 3x1s are an issue from looking at the Defender, but I haven't tried building with those wheels.  I guess to drive it you'd need a U-shaped rack to clear the differential.

Should be the same behaviour as the 5 long ones, just with enough clearance to still be able to steer.

Edited July 30 by Stereo

[Attika]

30 minutes ago, Stereo said:

 

Should be the same behaviour as the 5 long ones, just with enough clearance to still be able to steer.

Is the left side of your picture represents your understanding of my concept?

[Stereo]

No, I just couldn't find the hub pieces and that quarter ellipse has the same holes.  It's the way the link is set up on the Defender.

Edited July 30 by Stereo

[Attika]

2 hours ago, Stereo said:

No, I just couldn't find the hub pieces and that quarter ellipse has the same holes. 

I see. Sorry it wasn't obvious at first glance. I tend to loose plastic parts. Not the digital ones. :-)

[Jerry LEGO Creations]

Nice work, might look into it further for future builds!