[TC18] Porsche 911/964 AWD

[Limga]

Hello, everyone! This is my first attempt to participate in Eurobricks contest. I am glad to see a lot of entries and I must admit that I had a lot of inspiration and ideas from them.

As you can notice from the topic's name I am going to build Yet Another Porsche, since I am among the others Porsche-lovers.
The features I want to implement:
1. All wheel drive with three differentials.
2. Independent suspension on all wheels.
3. Working steering wheel and detachable HOG.
4. Two rows of seats (something you don't see very often even in the bigger scale).
5. Working Flat-Six engine with Boxer configuration (not Flat V180, cause it is Porsche)
6. Openable bonnet, trunk and doors with locks.
7. Foldable front seats (you need to access back seats somehow, right?)

I guess the list of features looks very optimistic, since the scale doesn't help at all. But I do love these challenges, as they make my head burn in thinking how to solve them.
Also I did want to integrate a 4-speed gearbox or at least a DNR-gearbox. I did come to some compact solutions, but every one of them would ruin the interior and backseats. I still hope to somehow manage it, but reluctantly I discarded gearboxes for now. 

So far I have a prototype of the front axle and the fake Boxer engine. 

Front axle.
I am really proud of the front axle solution, but I need to thanks other builders with similar setup which gave me inspiration.
It is double wishbone indepent suspension with floating differential:

 

The engine.
The idea was to make a model of real Boxer engine where pistons are moving symmetrically, since the Boxer engine are the ones that are used in Porsche. The difference between Boxer and V180 is under the spoiler.

Spoiler

 The upper one is Boxer engine and the bottom one is V180.

The classic engine with camshaft and pushrod would be too big in Boxer configuration, so I used the idea with 2L axles and 1x1 plates. The only problem was to make axle move back after is was pushed by the plate. Luckily, @Thirdwigg referenced to this post (in spoiler) and I had the solution.

Spoiler

On 3/31/2020 at 5:08 PM, Thirdwigg said:

@steph77 had a good little idea for a mini flat engine. Take a look here, and see if it can be helpful.

 

After several iteration, I came up with this. Maybe it can be made even smaller using halfpins but I am already satisfied with the result. Antenna bars are used to prevent axles from falling out in case engine will be tilted. Also, in my opinion, they do look like camshafts to operate valves:)


That is all of the progress for now. I do have some ideas for features I listed and would happily share the progress. Stay tuned!

[Bartybum]

Looking good so far.

Bit of a curveball question but is your username a typo of ligma?

[Limga]

Just now, Bartybum said:

Looking good so far.

Bit of a curveball question but is your username a typo of ligma?

Thank you!
You are not the first one to ask. Unfortunately since this "joke" appeared I do receive sometimes offensive taunts regularly.
My username is just my real name with changed syllables. My name is Galim and limGa is derived from it.

[Limga]

I made an LDD-file of the front axle prototype to share. Note that it is better to use it with the new differential from 42109, since 20-tooth gear scrubs the steering axle in the upper suspension position.

[sirslayer]

I had a cat name Amiga!!!   I don't get how the fake engine works !!! looks like valves lifters 

Edited April 11, 2020 by sirslayer

[Limga]

1 minute ago, sirslayer said:

I don't get how the fake engine works

2L axles are pushed by 1x1 plates and return under the weight of 2L beam.
I made a short video with demonstration:

 

[Thirdwigg]

Glad to help. The engine looks great. 

[sirslayer]

Thank you, @Limga ..  very effective as a motor...  

[jorgeopesi]

I have seen this front axle and I have to say that I couldn´t use it, when the wheels turn the gear rack and the connector haven´t got a natural movement, too much for me. I know we have tolerance but I have very little. 

Edited April 11, 2020 by jorgeopesi

[Limga]

25 minutes ago, Thirdwigg said:

Glad to help. The engine looks great. 

Thanks! I still need to replace lime plates with neutral LBG ones. 

6 minutes ago, sirslayer said:

Thank you, @Limga ..  very effective as a motor...  

I can share an LDD file of engine later if it is needed. 

2 minutes ago, jorgeopesi said:

I have seen this front axle and I have to say that I couldn´t use it, when the wheels turn the gear rack and the connector haven´t got a natural movement, too much for me. I know we have tolerance but I have very little. 

I do wonder where have you seen such front axle? I haven't seen them.
Everything moves freely even if wheels are steered and suspension is pushed. Sure, it does rely on backlash and play between parts, but so do many steering mechanisms in official sets. I provided LDD-file earlier so you can build it yourself and test.
I also recorded a prompt video of axle. Pretty hard to show it only by one hand, thought.

 

[sirslayer]

The differential is bouncing around and causing the gears to skip???  I guess as long you don't motorized the chassis..  

[jorgeopesi]

4 hours ago, Limga said:

I do wonder where have you seen such front axle? I haven't seen them.
Everything moves freely even if wheels are steered and suspension is pushed. Sure, it does rely on backlash and play between parts, but so do many steering mechanisms in official sets. I provided LDD-file earlier so you can build it yourself and test.
I also recorded a prompt video of axle. Pretty hard to show it only by one hand, thought.

The Muscle car from Zerobricks uses a very similar front axle but he fixes the problem using 2 axles 3 with stop between the gear rack and the connectors, when Lego uses independent suspension always uses Technic links. As I said I know there is tolerance between parts but it is something I can´t do or value.

[Limga]

12 minutes ago, jorgeopesi said:

The Muscle car from Zerobricks uses a very similar front axle but he fixes the problem using 2 axles 3 with stop between the gear rack and the connectors, when Lego uses independent suspension always uses Technic links. As I said I know there is tolerance between parts but it is something I can´t do or value.

Ah well, I thought of the suspension with drive. In fact, Zerobricks' solution was the one that inspired me.
I do respect your viewpoint, since I by myself have some strict principles regarding building technics. I think I can manage to do it without using tolerance play, and I have already some ideas in mind. Thank you for your opinion! Now I want to make it "clean" and deserve your approval

[Limga]

@jorgeopesi, I cleaned a room for gear rack to move backwards when steering. I guess, this can be counted as "clean" solution. What do you think?

[jorgeopesi]

I like it too much now but it is only my opinion. Most people will vote only for aesthetics because they won't see the threads in detail but this is our technic world.

[BusterHaus]

42 minutes ago, jorgeopesi said:

I like it too much now but it is only my opinion. Most people will vote only for aesthetics because they won't see the threads in detail but this is our technic world.

Agreed.  This is a very nice example of engineering, but I get the feeling that it will only be appreciated by future builders who search for narrow independent/driven/steered axles.

By the way, the CV joint is key to fulfilling these three criteria at this scale.  I used a very similar solution today, it also used the CV joints.

[Bartybum]

It’s worth pointing out that using tolerances to aid with mechanisms is allowed by Lego, since 42101’s steering should technically be impossible, as is almost every example of torque tube suspension seen in official sets.

Edited April 12, 2020 by Bartybum

[Shtykoff]

Cool start and a bunch of features!

[jorgeopesi]

3 hours ago, Bartybum said:

It’s worth pointing out that using tolerances to aid with mechanisms is allowed by Lego, since 42101’s steering should technically be impossible, as is almost every example of torque tube suspension seen in official sets.

I totally agree with you, in the end Lego is an excuse for me to think and that Lego sometimes break rules (onwritten rules  ) doesn´t mean that I want to do it, IMO when you break an own rule it is hard to see the limit for stop to do it. Sorry for the off-topic Limga.

[vascolp]

I like very much the front drivetrain. 

And the engine!

[Limga]

On 4/12/2020 at 1:29 AM, jorgeopesi said:

I like it too much now but it is only my opinion. Most people will vote only for aesthetics because they won't see the threads in detail but this is our technic world.

On 4/12/2020 at 2:22 AM, BusterHaus said:

Agreed.  This is a very nice example of engineering, but I get the feeling that it will only be appreciated by future builders who search for narrow independent/driven/steered axles.

I do understand you, since I am more engineering guy than aesthetics. But for me this isn't a competition between engineering and aesthetics, it is just a challenge for myself. For me it is already enough that there are several people that appreciate my efforts, so I am glad to make a contribution to Technic community.
But I also would like to make a beautiful exterior and that would be quite a challenge, since I do have much more experience in the suspensions and not in the bodyworks.

On 4/12/2020 at 2:22 AM, BusterHaus said:

By the way, the CV joint is key to fulfilling these three criteria at this scale.  I used a very similar solution today, it also used the CV joints.

I am interested, can you show your solution?

On 4/12/2020 at 7:32 AM, jorgeopesi said:

I totally agree with you, in the end Lego is an excuse for me to think and that Lego sometimes break rules (onwritten rules  ) doesn´t mean that I want to do it, IMO when you break an own rule it is hard to see the limit for stop to do it. Sorry for the off-topic Limga.

I do agree. Sometimes it is really tempting to use some "illegal" solution, but in the end the "clear" solution brings much more satisfaction.

On 4/12/2020 at 6:47 AM, Shtykoff said:

Cool start and a bunch of features!

On 4/12/2020 at 7:58 PM, vascolp said:

I like very much the front drivetrain. 

And the engine!

Thank you! I almost forgot how it is pleasant to hear compliments about yours MOC 

 

[Limga]

So, there is some updates.

Rear axle (with mounted engine).
For the rear axle I did not want to copy the front axle solution or make another type of kinda boring (for me) double wishbone suspension. Classic Porsche 911 uses semi-trailing arms for the rear suspension  I a priori discarded the idea of implementing semi-trailing arms with oblique swing axle in that scale and used the combination of trailing arms and multilink suspension. I also wanted to put shock absorbers as close to rear as possible to make space for the backseats. And, of course, suspension uses floating differential setup, but with U-joints instead of CV-jonts. So, here is the result:

For the transversal suspension arm I used rubber 2L beam as a rubber bush that allows arm movement in "legal" way.


And small animation of rear suspension at work. Guess it has too much of travel and I will need to make some sort of a limiter.


I stil need to figure out which ground clearance should be. Unfortunately rear and front axles have slightly different clearance and it isn't easily adjusted. I think I will figure it out when the weight of bodywork will be known.

As for now current task for me is to make working steering wheel, reserve a place for a HOG and marry front and rear axles togethers. Luckily, the wheelbase is just what is needed by scale and center differential fits perfectly. Thank you for the attention and all of the comments! 

[Jurss]

Really interesting suspnesion concept.

[agrof]

I am sold on the suspension, it is just ingenious! 

Maybe an idea to replace the #1 connectors to 2x4 liftarms (2-er side inwards), so the traversal arms would be fully rigid?

[Limga]

18 minutes ago, Jurss said:

Really interesting suspnesion concept.

16 minutes ago, agrof said:

I am sold on the suspension, it is just ingenious! 

Thank you very much. I do love solving the puzzles of making some unusual types of suspension. 
 

18 minutes ago, agrof said:

Maybe an idea to replace the #1 connectors to 2x4 liftarms (2-er side inwards), so the traversal arms would be fully rigid?

Thanks for suggestion, I didn't even think about it. I tried it now and, unfortunately 2x4 liftarms do scrub against differential at one side, something I cannot afford. But I think the rigidity of #1 connectors is just enough for manual model and also should work fine with RC-mod (I do have plans for RC-mod after contest is finished).

By the way, some teaser of the whole chassis. Right now I don't even know what dimensions should the seats have but I have an intuitive guess two rows of seats should fit.