[WIP] Ferrari 125s in 1:8 scale

[Divitis]

6. The evolution of the front axle - circa 22th to 30th of December

Predictably, the steering and suspension systems evolved side by side - and the motors kept changing position. 

In the case of the steering, the arms are still too long and introduce a lot of play but the biggest immediate challenge was constructing a solid bracing around it all, to prevent the black cube from spinning. As it turns out, it's crucial to remove as much wiggle room and bending as possible from the system, as even a small amount prevents the C+ app from calibrating. A hard stop is required so relying on the wheels touching the fenders, for example, won't do. At the time, I created a dedicated topic for it so I won't be uploading too many iteration steps here.

 

And these are the key learnings from developing the suspension system. Not necessarily al learnt at this point in time of course - gosh, I am still far away from the first test drive!

• When testing suspensions, don't push the suspension arm up with your hand. Push the wheel up instead. This is how the actual forces will work on the model. It's going to be irritating to see your ball joints pop up out but it will save you the much bigger frustration of the same happen at a later stage.
• How to brace suspension components or 'which way things push when the suspension is compressed'.
  • The shock absorber (red 6l liftarm) pushes up (Blue bracing). 
  • Both suspension arms push down. (Orange and lime axle bracing)

Result of the set-up above: The orange connector holding the upper arm is sure to pop out. Understanding this interplay helped me immensely with developing a reliable digital model. This 'production diary' is meant to be useful to noobs like me, so experienced builders please forgive the long excursus. 
 

In the image above you can also see how the 'unequal-length wishbone' setup was implemented. Very simply, the upper arm (orange connector) pivots one stud closer to the ball joint than the lower one (lime axle).
This is what ChatGPT regurgitates:
In a car suspension system described as 'unequal length double wishbone' or 'short-long arm suspension', the lower arm is the longer one. This design allows for better handling and improved tire contact with the road throughout the suspension travel. The shorter upper arm and longer lower arm help to control the camber changes that occur during cornering, enhancing the vehicle's stability and grip.

 

Finally for the steering itself: playing in Studio, it looked like 30 degrees of rotation of the wheel hub in both directions (60 total) could realistically be achieved, and so it became my hard goal. And I never strayed however, in insight, I reckon I could have been a bit more lenient with myself. 

 

To your points:

9 hours ago, 2GodBDGlory said:

I'm enjoying your serialized presentation of the model's development! It must be a lot more work for you to type so many updates, but it's fun to see a sort of WIP thread without the long waits between updates you'd have in a normal situation

 

8 hours ago, NV Lego technic said:

From my experience, it's much quicker and kind of fun to write updates.

I am really glad to hear you're enjoying the read :)  It is kinda fun but also some work, especially because I'm not exactly reporting on a linear development. Very often the files prove that I was experimenting in circles and so must select the relevant elements and create a narrative around them.

Still, I've been spending my evenings for the past six months working on this, so now that I'm only waiting for orders to arrive and one piece to be officially released, I can spare the time. 

 

Next up: Revolution #1. How most of everything got thrown away and completely redesigned in the name of accuracy. Because sometimes three plates are too many.

Edited July 4 by Divitis

[NV Lego technic]

What piece?

[Divitis]

7. Sometime between Christmas and New Year..

.. I started blocking out more of the interior including the seats and suddenly realized the many things that were out of place or out of proportions.

 

Firstly, the engine is too big. Just compare it with this incredible historic image.

And it makes sense, considering that in 1:8 cars the classic engine pieces are used to represent engines of 5000cc and more. The 125s only has a 1500cc engine.
Below are some explorations of a more compact design, and different ways of achieving the 60 degrees inclination.

 

Then, secondly and more important: the cockpit floor (visible in lime/yellow in the first image) sits way too high compared to the lower edge of the door. That won't meet my accuracy standards. This car is a cabrio, so no compromises can be tolerated on the insight. My goal is to achieve a 'model team' look.

So, the gearbox gets moved to the front, under the fake engine, and converted to a more traditional design, while the two L motors are shuffled about yet again, this time to where I assume I'll be able to hide them under the seats.

The gearing isn't tuned yet, but the linkage to operate it through the stick makes its appearance. It's 2u tall, and the plan is to lay the cockpit floor directly on top.

In fact, the missing piece is the 'flip flop' 6L linkage that was discovered in the upcoming mars rover. - @NV Lego technic

 

Next up: Madness and perseverance.

Edited July 5 by Divitis

[1gor]

Perhaps new engine peaces (from Kawasaki) would be useful to you...

To represent classic Ferrari in 1:8 scale with those (big) cylinders, you had to choose 625 Targa Florio, or 500TRC 

[2GodBDGlory]

On 7/6/2024 at 7:08 AM, Divitis said:

In fact, the missing piece is the 'flip flop' 6L linkage that was discovered in the upcoming mars rover. -

It'll be fun to see a use for that! I also like the use of the towball-bar-pin thing for the shifter-it looks like it works really nice there!

[Divitis]

8. Madness and Perseverance over the holidays and beyond

This update won't be much technical, I'm afraid. But I want to share that I find both madness and perseverance as crucial to success when one bites way more that they can chew, such as I am.

The catch is:  you need to embrace their folly and turn it into calm. Lego it's a hobby 

 

Madness
I'm thinking at the dozens iterations of the gearbox planned in my head during the Christmas days and lunches and dinners and gifts wrapping and unwrapping, only to inevitably find them faulty in the evening when, after putting the family to bed, I would start building.
Suffice to say, this is what will eventually go into testing once the parts arrived.
I could see that it doesn't look elegant, with the asymmetrical motor placement and the extra gearing between motor and steering, but I had nothing better.

 

Perseverance (and spoiler)
This happened only three days ago. I was on the couch after a test drive when, looking at the car from a different angle than usual, I noticed it sits lower at the back - my fault for building the digital model in Studio with the front suspension compressed.

Ever since, I've been spending my days re-designing the rear axle to match the front.
Because perseverance means that even only being sloppy once is unforgivable.

To your points:

On 7/6/2024 at 12:33 AM, 1gor said:

Perhaps new engine peaces (from Kawasaki) would be useful to you...

To represent classic Ferrari in 1:8 scale with those (big) cylinders, you had to choose 625 Targa Florio, or 500TRC 

The Kawasaki was still to be released then, and it won't for a while. On January 28th I'm still concocting the most bizarre designs with @Jurss.

BTW, it looks like you know way more about Ferrari than I do. Did I mention I don't care for cars much IRL? 

 

On 7/9/2024 at 8:50 AM, 2GodBDGlory said:

It'll be fun to see a use for that! I also like the use of the towball-bar-pin thing for the shifter-it looks like it works really nice there!

The model ends up using several links, not just for the gearbox and I've been considering the new piece since I know it exists, however keeping in mind it won't be cheap! My impression is that having both options will be a great design simplifier, rather than a game changer.
So far only in one case the new one proved indispensable. But then again, maybe 10 more hours of tinkering would have allowed for the classic one to fit.

 

Next up: Custom wheel hubs

[1gor]

Actually I don't care a lot about modern cars because they get  broken more often than classic cars and I like design of some classic cars... That's all...

Edited July 16 by 1gor

[Divitis]

8. Custom wheel hubs 

As soon as I got my hands on the wheels of the Vespa I realized that my approximation was too generous, and I will have one module less of space to play with than I thought. (The wheel hub doesn't sits at the center of the tire and not offset as I had assumed.

So, with the wheel hubs I wanted to use the wheels would stick out one stud and I had to swap them for custom build solutions. Instead of being frustrated, I remember how happy I actually was that more engineering would be needed. 

This is how the front turned out (for some reason the caster angle has increased, I suppose to make it a one stud offset between arms rather than a half)

 

And this for the back, using the Ford GT links and new 3L flip flop beams. (some bracing is missing in the picture to allow seeing what's going on).

The biggest challenge is giving enough clearance to the differential, so that it doesn't touch the battery box when the suspension compresses. That battery box is so big and pushing it even just a half stud higher would ruin the profile of the car.

So finding a solution was a very frustrating process - of which I'm sparing you about a dozen iterations - suffice to say that I got really close to getting a Buwizz before devising this and seeing it work smoothly enough. 

Both the forage harvester and the Ford GT other parts are in the drawer now, thinking maybe I'll get around building them sometimes. So somewhat of an expensive solution. 

Anyway, armed with new confidence, I even took a stab at the car seat.

Little did I know the end was so far away.

Next up: New gearbox and first test drive. And inevitably, revolution #2.

[Paul B Technic]

Amazing updates :)

[Divitis]

February 8th: New gearbox and test drive

The new gearbox design has the input on the left (red) and output on the right (green) with a u-joint routing the motion back in the center (one 16t gear on the left side is missing in the image below).

 

In order to keep the gear ratios realistic, the 1st and 5th gears need to be between 4x to 5x apart and that's easy enough.
It's making sure that the gears sitting on the same ring aren't too close or too far apart however, which proved more tricky.

 

On the right side (image below), you can see the solution: R, 1st, 3rd and 5th are geared down by a 12t to 20t ratio, while 2nd and 4th are geared down by 16t to 20t. The 'streams' merge through two 8t gears. The triangle liftarm is my favorite piece, so I was super happy to put it to good use :)

On the left, some complicated gearing gears down the R gear and inverts its rotation through two clutch which spin freely at slightly different speeds on the orange axle that meanwhile serves as the main input.

Looking back at this months after designing it, I needed some time to wrap my own head around it. 

The final ratios are:
R:   0.12
1st: 0.12
2nd: 0.16
3rd: 0.36
4th: 0.48
5th: 0.6

Am I happy with the jump between 2nd and 3rd. Hell no. But it's also about time I take this baby for ride.

The first test drive was a total failure.

The wheels at the back pop out after less than a meter and the front custom built wheel hub cannot really stand the weight of the model and sags and bends.
However, the car at least moves, even if only in R, 1st and 2nd gears. Then some of the bracing pops.

I regret not having a video, but it probably happened late at night when I was the only one awake, and I cannot seem to film and run the C+ APP simultaneously.

 

The learnings:

- proper wheel hubs are a must at 1:8 scale.

- gears tend to push one another apart vertically rather than horizontally. The teeth effectively push up (or down) the other gear and only when the bracing is strong enough rotational movement starts.

 

All in all, plenty of lessons learned and a s**tload left to do! 

 

Finally, did you notice the three 2L driving rings connected to the motors and the gearbox input and output?
Next up: All about them, and the belated discovery that the car is asymmetrical. 

[karmadrome]

Fantastic model, fantastic write-ups on your progress. This is a joy to follow.

[Paul B Technic]

It is really good to see your progress with this, keep the updates coming :)

[Divitis]

On the secret switches

With the failed test drive where the car could only go as fast as second gear, I started doubting that I could make it ever go fast through the gearbox, even with better bracing.
And so what would it be the point of making it motorized at all?

So I devised this solution:
#1 Connects the motor output and the gearbox input
#2 Connects the gearbox output and the drive axle
#3 Directly couples the motor output and the drive axle tot he wheels

Then, the following is possible.

• The car runs through the gearbox (#1 on, #2 on, #3 off)
• The gearbox is fully excluded from the drivetrain for uncompromised performance (#1 off, #2 off, #3 on)
• The car becomes a push-along model with fake engine running at constant speed (#1 off, #2 on, #3 off)
  • In theory the M angular model can be back-driven (it can be used as a rotation sensor) so one could even steer the car through the steering wheel, albeit somewhat inconveniently.
• Watch the fake engine run at different speeds while the car stays still (#1 on, #2 off, #3 off)

Unfortunately I couldn't see a way to add levers to operate these switches without compromising the aesthetic. Which sparked the idea of building a base for the model, from where they can be operated, ideally with some mechanical trickery to make it impossible to turn #2 and #3 on simultaneously, which would mean disaster.
I'm actually going het started on this tonight (time of writing). 

 

On the asymmetry of the car.
To my knowledge, two 125s exist today and they are slightly different (one has two windshields and the other one, only one has a parking brake). So when fetching images online I got used to incongruences.
But I wasn't expecting this:

One of the 125 S' most interesting features was that it had just one conventional door, on the passenger's side. On the driver's side, there was a cutout in the metal panel through which the pilot jumped inside.

And it's then that I begun really liking the 125S. A Ferrari made for pilots, not fat millionaires. 

As a perk, the one door setup should make it easier to reinforce the chassis. 

 

Thanks @karmadrome and @Paul B Technic!

I means a lot reading that my updates are appreciated. And I hope this thread will help fellow inexperienced builders who want to embark on a similar challenge :)

 

Next up: The evolution of the front axle

Edited July 17 by Divitis
Mistakes in the 'following is possible' section

[2GodBDGlory]

I like the sound of that multi-mode system for the gearbox, to allow you to have modes for realistic gearbox operation, but also good performance!

Looking forward to the next update! This is one of my favourite threads I've seen on here in a while! A really creative, interesting model, slowly being revealed with great presentation!

[Paul B Technic]

You have even got me thinking about building something like this.

[Divitis]

#12 Evolution of the front axle (again)

I realize this is the second post on the front axle (see top of the page). Apologies if it gets boring, but the duplication reflects my struggles with it. 

 

Steering and suspension need to be developed together and the new challenges are:

• Offsetting the wishbone arms half a stud towards the center to allow using regular wheel hubs.
• Shortening the steering arms as much as possible to reduce play in the mechanism.
• Connecting the two, now that they are unevenly spaced. This literally drove me nuts, just look at that lime mess which was the best I could do after days of trying!
• Routing the movement back to the steering wheel (in yellow below). It would be much much easier if I could rotate the motor so the output is closer to the cockpit, but then the cable wouldn't reach the hub. Of course, I had to rebuild everything to find out.  

Minus some bracing, this is about 90% there compared to what's in the final model, where the 'transversal leaf spring' also found a way in. 
I'll leave it at that for this WIP thread so there's some unknown left for the eventual reveal.

 

Learnings:

• The right placement of the shock absorber is right on top of the lower arm for sturdiness.
• When the suspension is pushed hard (In my strive for as good as possible, I'm treating this Ferrari as a Mad Max stunt car) the 5l liftarm connecting the upper and lower arm wasn't enough and the wheel hub popped out, I reckon partly because of the imperfect geometry (one arm longer than the other). Eventually, the weak point proved to be the towball pin connection to the hub. So switching to the Audi one solved the problem entirely.

 

To your points:

On 7/18/2024 at 1:17 AM, 2GodBDGlory said:

I like the sound of that multi-mode system for the gearbox, to allow you to have modes for realistic gearbox operation, but also good performance!

I am indeed proud of this system, it feels like 'overcomplication with a purpose' since it improves playability a lot.
Over the course of the development this actually disappeared but then luckily found a way back in.

 

Next up: Plans are useless, but planning is fundamental. Stud.io dependency vs embracing imperfections.

[Divitis]

#13 This won't be a technical update, but one I hope fellow noobs will find it useful to avoid some of the pitfalls I fell into.

 

Plans are useless.

Before this project, I had never used a technic panel in a MOC, and had next to no knowledge of their sizes and availability. So after starting with the 125S, whenever I ordered some pieces, if the store had red panels available at a reasonable price, I would get some just in case.
Result: the car is pretty much built while the drawer is still full. 

 

but planning is fundamental.

I have a habit of purchasing pieces 'just to have them' even when they seem like p.o.o.p.s or useless gimmicks, at least when compared to the simplicity of the parts lineup of my childhood. But without these two, the bodywork would have not been possible, or it would have been rather flimsy.

 

A well assorted drawer of 'what if' bricks makes it much more easy to try out ideas and reduces the frustration of waiting for parts. How many times did you have to put a design on hold waiting for that part to arrive in the mail?

It is also cheap enough to maintain, especially if one buys pieces in random (cheapest) colors.

 

 

Stud.io dependency vs embracing imperfections.

To me, working with Studio is less cognitive demanding than the real bricks, maybe because I play late at night. So I often find myself working on, say, a supporting structure and wonder 'will it be sturdy enough'? rather that quickly building it with real bricks.

Another bad habit is always building to perfection in Studio, which results in either impossible constructions or very difficult ones that need to be put together in a special way.
The 3L pins  eventually became my best prototyping friends and now I no longer feel guilty using them when I know a 3L blue pin could theoretically be fit.

 

Next up: Another (the last) gearbox revolution. Because the previous one wasn't accurate enough.

[Divitis]

#14 Let's talk gears again!

I wasn't in love with the gear ratios and generally the gearbox output being on one side and needing u-joints to be brought back to the middle; I was afraid they'd rub on the cockpit floor - which I intend to cover with plates. Also for realism, I wanted to make the whole gearbox one stud shorter and give more legroom to the cockpit.

And so, I bode my farewell to the old solution and worked out something entirely new going backward from the output upstream. 

To accommodate the output axle, the gears axles must be placed asymmetrically - two on the left and one on the right of the central axle. All three on the same size would mean having the outermost link at an angle, which increases stress.

 

The intuition was using the same axle to both transfer movement between gears and receive their output finally passing it on to the output axle (green). The classic 16/24 diff was also considered but there were no 12t spur at the time to engage the bigger side.

Luckily I had some 2L rings available. Blue friction pins work very well to keep them from sliding in and out of gear.

 

Positives:

• Realistic output. Now the gear lever sits right on top of the axle.
• Much better gear ratios: 
  • R:  0.297
  • 1st:  0.29
  • 2nd: 0.45
  • 3rd:  0.80
  • 4th:  1.25
  • 5th:  1.33
• Way less slack than I thought - at most the car needs to roll for about 20cm before the pistons move. Better than I imagined.

 

Negative:

The gearing for R. But I guess I'll have to leave with it being slightly faster that the 1st. I reckon if a compromise has to be made in a race car, reverse gear is a tolerable one.

I had to abandon the 'modes' system illustrated above. But we already know it's only a temporary setback. 

 

 

Tip: An Excel sheet to calculate gear ratios saved me from a head hake, or two 

 

 

Next up: miniaturizing the gearbox stick, and early bodywork

Edited July 23 by Divitis
Tip

[2GodBDGlory]

Ooh, that's a fun gearbox! That technique passing drive over another axle is pretty unusual for sure! 

I'm curious to see how you'll make a gearstick for it with the extra-large gap between 1/2 and 3/4

[Lipko]

Nice project. I wonder how it Will come along as the source material doesn't really fit modern Technic.

To the "what if parts" part: for prototyping, I often cut and craft parts I don't own yet. Even Paint, if my imagination is nőt sufficient.

[dantheman12]

Love the consistent updates, makes me want to put more of my time into building my current projects :)

I really like your solution for the gear shifting using the linkages, but was wondering if if they have too much wiggle room? I've been trying to build a 6 spd manual gearbox, and one of the main things I want is for it to feel realistic, even if its going to be hidden away. I may try something similar to your design (and give credit of course) hopefully I can come up with something worthy of an update.

I also really like your attention to detail and the effort put into perfecting things, will be looking forward to seeing the finished model.

I found your update about prototyping and stud.io very relatable, the amount of times I've completely rebuilt my front suspension to increase the sturdiness by replacing pins and etc  

[Divitis]

#15 The gearbox stick and linkage system

This is the initial linkage system to operate the gearbox. I'm reproducing it in full to give a sense of scale respective to the whole chassis - it basically occupies all of the cockpit floor.

The ball join allows for surprisingly limited movements, because the axle connected to the ball touches the socket piece. This is especially pronounced for diagonal movements (exactly what you need to put a gear in). The easy solution is to 'multiply' the movement by placing the ball joint higher up and having a longer stick, but in this model it would look funny.

Eventually, I figured that one can increase and decrease the sensitivity of the mechanism by putting the pivot point respectively further away and closer to the rotation center of the changeover catch. So, I lowered the ball joint so less horizontal movement is needed to turn it, meaning less movement range is required on the gear lever as well. Also, the mechanism slides on two axles, very smooth.

 

But still the range of movement wasn't enough and I set out to miniaturize things further. In this early design, some of the cockpit flooring also helped with holding the yellow constructions in place.

The change to 2L rings meant the catches need to be placed at 1/2 stud offset. Together with securing the sliders, figuring out proper bracing was quite a task and for each test I had to fully disassemble the model.

The main drawback of this configuration is that the bar rotates inside the cross axe hole of the joint, making things finnicky to operates - for example, you think you're pushing while in fact your rotating the bar only.

And to further complicate things, in the 125S the gearbox is tucked underneath the dashboard and the lever bends towards the driver at a steep angle. Replicating this with bars makes the structure way too weak.

 

After countless prototypes, the lesson learnt was: one thing is what works stand alone, with the mechanism fully exposed so that one can fine tune their movements. Another what works when the mechanism is hidden and the lever hard to reach under the dashboard.

And so, finally, it was with a heavy hearth that I reverted back to a more conventional set up. It's hard enough to reach in there with adults fingers, no need to make the mechanics finnicky to operate.

I thought those who've kept up with my rambling until now would appreciate a little spoiler - some paneling and the pedals are still missing plus there are details I don't like but I reckon I'm mostly there. Happy to hear your criticism, of course 

 

To your points

@Lipko I never thought of painting parts before, but I might make an exception for the steering wheel. It'd be so nice to have it in brown. 

 

@dantheman12 I'm very happy to hear you're finding my updates useful. And by all means, please put the ball joint idea to good use. You won't be disappointed by it's realistic friction and maneuverability - with enough space allowed.

 

Next up:
The post got much longer than I thought, so I'll save the early bodywork ideas for the next one, together with some furious ranting over Studio.

[2GodBDGlory]

6 hours ago, Divitis said:

I thought those who've kept up with my rambling until now would appreciate a little spoiler - some paneling and the pedals are still missing plus there are details I don't like but I reckon I'm mostly there. Happy to hear your criticism, of course 

Oho, a teaser! Exciting!

[Paul B Technic]

Your updates keep reminding me to focus on my builds too :)

[NV Lego technic]

The interior looks very nice! More complete than most 1:8 supercars.