[WIP] Ferrari 125s in 1:8 scale

[NV Lego technic]

You really want to perfect this down to the very last part, soon it will have been a year since this thread started

[Divitis]

Very belated update, but I was too busy building. - spent almost 3 weeks designing a smaller and more efficient gearbox, finally fitting in the Kawasaki pistons, will indulge you with that next ;)

 

Now on the sagging of the front axle, the problem became apparent only after recording the video, which meant a lot of pushing on the hood, which wouldn't happen during normal racing. But I could not unsee it.

The reason was the black pins holding the connector in place were being pulled out. In green below: force applied either on the hood or pushing the wheel up (green) and the connector being pulled out (purple).

On the right the new assembly. On one side thisis firmly in place through the axle connection on one side. On the other, the 6L thin liftarm makes it so that for one connector to be pulled out, the other would have to be pulled in. Problem solved. 

 

Next up: A most efficient gearbox.

Edited July 13, 2025 by Divitis

[NV Lego technic]

I love how you let us know about every single detail and how you fixed it, this is dedication!

[Divitis]

I'll start with the lessons learned. When designing a parallel axis gearbox...

... the input should be on the highest gear, and then only reduced from there...

... big 'jumps' should always be avoided. By this I mean meshing gears very different in size, like a 12 and a 28...

... big gears transfer movement more smoothly than the smaller ones.

 

Now, with the design history. The original gearbox (here the post) was going like this: Input on the 1st/2nd gear shaft where it arrived already slowed down to 0.14 : 1. Which meant the 1st gear was 0.11 to 1 and the 5th gear was then geared up to 0.51 to 1.

It worked only because it run so slow, but it was massively inefficient.

I learned this the hard way after implementing the first working version fitting in the new small pistons, where I kept realistic rations between gears but started from a 1:1 input on the 1st gear shaft. Weeks of digital work for something that could not be moved past second gear. 

 

Come in the ultimate (dare I say final?) design:

Input (orange) on the 5th/R shaft from where it gets geared down to 0.34 : 1 for the 1st gear. (output is brown)

 

Note the half stud offset of the engine shaft, this allows two things: Fitting in the worm screw used for steering which connects to the tan pin with axle and squeezing two 16t gears underneath. Unfortunately the newer spur version collides, so I had to use the old one.

 

I am also happy about only using 3L rings as mode switches (on the input and output axles), as they don't need a locking system.

 

Oh, and obtaining Reverse and the corresponding reduction by only adding one extra gear (the red 24t meshes back into the green 2ot which the 5th gear uses).

 

Here's the final result (WIP build)

The final massive headache after bracing all gears and the links was connecting the engine shaft to something.. anything really... I could not find any space to add as much as a half bush for a pulley. Until  it dawned on me to simply insert a red belt between the cam piece and the 2L driving ring sitting on the output shaft.

 

Next up: Instructions WIP
Does anyone feel like reviewing what I got so far for clarity, so that I can continue with piece of mind?
So far they cover the first part of the front axle and steering.

Thanks in advance for the help!

 

[Divitis]

Hello folks, instructions WIP are available here: https://bricksafe.com/files/divitis/miscellaneous-/125s-wip/ferrari 125 s - instructions test_compressed.pdf

And of course the parts list for the steps covered: https://bricksafe.com/files/divitis/miscellaneous-/125s-wip/Ferrari 125 S - instructions test.csv

 

Comments and feedback would be greatly appreciated.  

This is going to be a daunting task which will accompany me through the hot August nights and I don't wish do do it twice :)

 

Does making instructions mean the car is finished? yes. I'm both having enough of it and don't know what to improve anymore. It is a bittersweet feeling.

 

Next up: New pieces = bodywork enhancements