[TC19] Suzuki Nuda Concept

[2GodBDGlory]

For this contest I decided I wanted to see how complex of a bike I could build, which led me to 2WD bikes, which, when narrowed down to mechanical systems with street tires, led me to Suzuki's 1987 Nuda Concept, which had 2WD with swing arm suspension front and rear, 2WD, a 6-speed transmission, an I-4 engine, and a fully enclosed exterior.

https://www.cyclechaos.com/wiki/File:Suzuki-nuda-1987-1987-1.jpg

I wanted to include the full six speeds in a compact model, so I turned to some prototypical gearbox designs I had made before with weird spacing allowing a wave shifter to mesh with three driving rings at once for a six speeds. I built a model tonight and attached it to an engine. Changes may occur, such as adding a clutch potentially, but this is the concept.

 

 

 

 

[Rudivdk]

Wow, 2wd, 6speed, you're going the full monty! Looking good sofar, but I'm most interested in how you'll solve the front wheel with drive and steering. Will follow this one closely.

Good luck!

[Gray Gear]

That is exactly how I thought you were going to approach this contest  Just search for the most complicated concept and lets go!

Looking good so far 

[amorti]

Curious to how that gearbox works - how do you get 6 gears on a wave selector with 4 quadrants? I guess there are gears at <90° increments?

I can't even imagine how to do hub centre steering in Lego. If you pull that off this will be very impressive. Even if you have to skip working steering, it'll be quite a thing to get 2wd.

[Jurss]

Nice powerplant.

I also thinking about 2WD, but still not get some satisfying mechanism, but not swingarm suspension.

[2GodBDGlory]

6 hours ago, Gray Gear said:

That is exactly how I thought you were going to approach this contest  Just search for the most complicated concept and lets go!

Looking good so far 

Yep, I guess I'm predictable...

5 hours ago, amorti said:

Curious to how that gearbox works - how do you get 6 gears on a wave selector with 4 quadrants? I guess there are gears at <90° increments?

I can't even imagine how to do hub centre steering in Lego. If you pull that off this will be very impressive. Even if you have to skip working steering, it'll be quite a thing to get 2wd.

The gears are actually not at 90 degree intervals, because that would result in two gears being engaged at the same time. Instead, they are set up sort in a rhombus pattern, where all three driving rings are touching each other and the wave shifter. This requires weird spacing, that is hard to reinforce, but this is only a manual model anyways. True hub-centered steering would be hard to make unless I use a defender rim (ugly), but I will see how close to the center I can get.

[MinusAndy]

Clearly Suzuki were mad in the 80’s! Remember street hawk? A Suzuki katana, the motorbike with a pop up headlight.

you could possibly do hub centre steering from outside the centre line using a vpp?

[2GodBDGlory]

21 minutes ago, MinusAndy said:

you could possibly do hub centre steering from outside the centre line using a vpp?

Hmm. I hadn't thought of that, and it could work well, but it would make adding the front wheel's drive a nightmare. It is a possibility, though.

[2GodBDGlory]

I just got a Ducati, so the build can proceed with realistic tires!

[2GodBDGlory]

I've made some more progress on the model. The drivetrain assembly has been modified to strengthen it while making the engine horizontal, like the real one, and a stepper was added. I also built the swing arms for the front and rear. The rear one is quite simple, but the front one is much more complicated. It uses a virtual pivot steering system, as suggested by MinusAndy, and a complicated system of bevel gears, universal joints, and a sliding axle to drive it. There is also a small castor angle. Next I will focus on connecting the axles.

 

 

 

[Jurss]

But that mechanism sticks out so much. And how You will make it really strong, to hold weight of that motorbike?

That is why I skipped this idea of 2wd after some trys.

[2GodBDGlory]

18 minutes ago, Jurss said:

But that mechanism sticks out so much. And how You will make it really strong, to hold weight of that motorbike?

That is why I skipped this idea of 2wd after some trys.

Well, I have strengthened it a fair bit already, and although it is definitely too wide, I am willing to sacrifice the aesthetic to add the functionality.

[BrickBuildingFox]

On 12/27/2020 at 6:15 PM, 2GodBDGlory said:

I am willing to sacrifice the aesthetic to add the functionality. 

I like that spirit! I'm looking forward to see a working 2WD

[2GodBDGlory]

Here's another update:

The swing arms have been modified a lot to make them stronger and to make the wheelbase right. They have been attached to the drivetrain module, and shock absorbers have been added. The rear one has too much twist in it for now, and the front one was even worse, so I was forced to add a ugly vertical axle to keep it straight. The basic steering linkage has been added, as well as a pedal and flex system operated rear disc brake. My next plans are to work more on the brakes, improving the rear one and hopefully adding a front one. I will also need to install handlebars. Unfortunately, I have no room to install a stepper, so the pedal-operated shifter rotates an unrealistic 360 degrees, and I have nearly given up on finding the room to install a clutch. Here are some images of my progress:

 

 

 

 

1 hour ago, BrickBuildingFox said:

I like that spirit! I'm looking forward to see a working 2WD

Thanks!

[2GodBDGlory]

Never mind about the clutch not fitting. I thought a bit more about it, found some space, and installed one!

[Gray Gear]

This is getting intresting!

What is that 8t gear in red color? Did LEGO ever produce 8t gears without friction, or is it just red by chance?

[amorti]

1 hour ago, Gray Gear said:

This is getting intresting!

What is that 8t gear in red color? Did LEGO ever produce 8t gears without friction, or is it just red by chance?

It's exactly that; a sliding 8t gear.

[2GodBDGlory]

On 12/29/2020 at 4:49 AM, amorti said:

It's exactly that; a sliding 8t gear.

Yep, that was the strongest way I could think of to obtain an extending axle with three studs travel.

[2GodBDGlory]

I have now added the front brake and the clutch, and connected them to levers on the handlebars, so I think I have added all the functions I want. I am sure they will be refined a bit further, but I think I am ready to start on the bodywork now.

 

 

 

 

 

[steph77]

I aml wondering how your gearbox worcks...

After hours of searching, mine didn't comes to life ever...

[2GodBDGlory]

4 hours ago, steph77 said:

I aml wondering how your gearbox worcks...

After hours of searching, mine didn't comes to life ever...

Well, mine only works because I was willing to ignore proper spacing. I have four axles (Shifter and three driving rings) arranged in a sort of rhombus shape, where each axle is about three studs away from both of its neighbors. In this way, the shifter can engage with all three rings at once. It requires careful shifting to avoid locking up, though, and I was forced to use 14T gears meshed with 20T gears to get the speeds in the right order. The best images I have of it are up at the top, but if you are still curious I could probably take some more once I am able to take the model apart.

[2GodBDGlory]

For the time being, perhaps these images can clarify its working principle:

[Rudivdk]

It's an interesting concept (but it hurts my purist nature of building 'in grid'). I've seen a similar layout long ago, using the v-engine support blocks as holders for the axles arranging them around a sliding center axle. The sliding axle made it possible to engage different gears and thus different speeds. I think it had 6 speeds as well, but the gear change mechanism was totally different and way bigger...

It looks like a 'standard' 90 degree sequential stepper will not give you the correct gear changes in your design, correct?

Edited December 30, 2020 by Rudivdk

[2GodBDGlory]

Yes, if the driving rings were at the normal 90 degree intervals it would result in the two opposite each other being engaged at the same time, stalling the gearbox.

[Gray Gear]

@2GodBDGlory I'll just leave this here, I just came up with it:

It shoud be easier to reinforce than your current design.

 

And proof the hole spacing is correct:

Looking forward to your future progress 

 

Edited December 31, 2020 by Gray Gear