[MOC][WIP] Nissan 180SX Type X

[Gray Gear]

@zoo I didn't even consider swapping an LS because I want to keep my MOC cars somewhat period-correct. Since the Type X was a Japan exclusive, I dont think there were many LS swaps done to this car in the 90's 

Since the SR20DET is a great engine with lots of tunig potential I decided to stick with it in the end.

[syclone]

Ohohoh, looking nicely there! Sorry for backtracking, but gosh darn the pop-ups look lovely  (coupé Silvia is still my preference though, something so charming about it)
Great to see SR20DET, such a shame there are no new, smaller piston housing parts (apart from 3D printed ones) 
I suppose no space/need for HICAS? (cannot even imagine how to implement it on a manual model except for being mechanically linked to the gearbox, but that would spoil all realism of it and probably would hinder the smoothness of gearshifting)

[Gray Gear]

@syclone yeas its a shame there are no smaller cylinder blocks, the engine is quite big, even for this scale.

 

I didn't even know some 180sx came with HICAS as well    But I dont think it would be a good Idea to try to implement it. First of all there are the problems you already mentioned, and second I dont think HICAS is really helpful with drifting 

I think I could make 4WD what is always active, but that would look weird especially on a drift car.

[LvdH]

Great design so far , and nice to see the development process as well.

Btw (slightly off topic) I will be building the NSX very soon, just waiting on some LEGO to arrive. I just have to see that gearbox design in person  

Edited December 19, 2020 by LvdH

[Gray Gear]

@syclone You've done it now, i have started playing around with with 4 wheel steering tech for the past 2 hours because of you 

@LvdH Happy to hear that. Due to the transverse engine layout of the NSX the transmission is also transverse. Because of that the transmission is different from the transmission system I am using in my other builds, and a bit more complicated. But out of all my designs it is still the smoothest drivetrain, there is not a single bevel gear used 

[syclone]

On 12/20/2020 at 12:39 AM, Gray Gear said:

@syclone You've done it now, i have started playing around with with 4 wheel steering tech for the past 2 hours because of you 

*snip*

 Well, as far as I´m aware Super HICAS was just an option on both Type R and Type X,  and definitely not a drifter feature  , though it is a very interesting piece of tech to improve handling. Hopefully this won't steer your project away too much)))

[Gray Gear]

I have always wanted to do something with 4 wheel steering, because I think it is really intresting, and it would upgrade the "technic value" of the model as well. The easy part is done: I crammed a rear wheel steering setup into my existing stransmission setup:

White Output is for the engine, small gear is for the rear wheel steering.

To fit the rear wheel steering setup I had to increase the length of the whole setup by 2 studs. Its okay I guess.

 

Now comes the hard part: I want to be able to switch the rear wheel steering on and off using a lever in the interior.

Honestly I have ho idea how I could achive this, and I am quite afraid I am digging myself a hole that's too deep to get out of. I would be very greatful for any bright Ideas, examples of other MOCs that use a system like this or anything else that could help me.

 

Thank you.

Edited December 21, 2020 by Gray Gear

[amorti]

Are the bottom control arms longer than the top arms?

Seems like if you have a simple two-speed transmission switch where one of the clutch gears joins to the steering input and one is locked, that'd do it? The locked one could mesh with another gear that's on an axle into a technic brick, or it could have a gear rack under it locking it in place.

[Jurss]

Maybe check how there was done switching between steering modes of Claas. I remember, that switching to another mode, returned also all the steering to straight direction.

[Gray Gear]

@amorti using clutch rings is not an option, they have way too much play

@Jurss Thanks, I'll have a look at it 

[LvdH]

One of the MOCs I am aware of that has an ''steering switch'' is Jeroen Ottens' Il Toro Azzurro, which has a sliding section that will either countersteer, crabsteer or not steer the rear axle. If I am completely honest, it doesn't work that well on the model my friend built. But maybe that mechanism can be refined. Also check out the 42054 Claas Xerion which I think has a similar mechanism. 

[2GodBDGlory]

Yep, the Class had a brilliant setup that should work fine for this model. I always wondered how they could do it without adding too much backlash, but after I built it, it all made sense.

[T Lego]

@Gray Gear I like your progress so far! Remember that no matter how long it takes, it's always worth the efforts in the end. So I would definitely encourage you to push yourself and this build to a higher level by incorparating the mentioned four wheel steering setup. I recommend taking a look at Madoca's Avtoros Shaman 8x8 which has a brilliant 4 wheel steering system with free instructions on Rebrickable. Good luck!

[MinusAndy]

I’ve been thinking about this to make the day at work pass quicker. Could you do something like have a rack setup on the rear wheels and have it controlled by the difference in outputs across the diff? I was thinking of it in terms of four wheel drive and running some sort of system like that across the centre diff? For a 2wd system this idea seems to work on paper at least.
I’m thinking that if you could take from each side of the diff and run those in opposite directions back into another diff, the casing would only spin when one wheel was going quicker than the other and that output from the casing could drive a rack that is spring loaded back to centre? I’ll try and build it in ldd as that explanation is probably about as clear as mud.

The red diff is the regular drive to the back wheels, The yellow and blue sides provide drive into the sky blue diff in opposite directions so cancel each other out when driving straight, Then if a wheel rotates quicker, the sky blue diff case will move, You could take this movement and use it to drive a rack or pushrod steering system, you'd need some sort of torque soak as the sky blue casing will continue to rotate while you corner. This would work like a semi open diff as the soak would create friction between the output axles.

The difference between the wheel outputs will be sent to the purple lift arm which rotates around the light grey axle. It will only be a pushing force due to the friction pin in the small bevel gear. I reckon the push will be ideal for hicas, especially if you have it sprung to centre. It should work in a correctional manner.

I hope the above helps.

 

Edited December 22, 2020 by MinusAndy
A.D.D

[MY1]

here's my idea:

so the first picture represents the gearbox you can have 3 16t gears and the red one, which my dog decided to chew up, is movable. the 2nd and third picture is the mechanism/ contraption. The first gear will be connected to the steering wheel so that it can turn whenever the steering wheel is turned. Next is the red gear attach the red gear to the contraption with a gray pin then attach the other end to a lift arm which can be connected to a lever mechanism in the cabin.  This allows the red gear to be pulled in and out of the way of the 2 gray gears. the third gear is attached to the rear steering rack meaning it can only turn when the red gear is in contact with it and the other gear. While this might look like a flimsy structure I would hope and assume you don't turn off the rear steering while your turning, that being said there is no friction that could cause the red gear to come off of the contraption 

[2GodBDGlory]

On 12/21/2020 at 6:04 PM, MinusAndy said:

The red diff is the regular drive to the back wheels, The yellow and blue sides provide drive into the sky blue diff in opposite directions so cancel each other out when driving straight, Then if a wheel rotates quicker, the sky blue diff case will move, You could take this movement and use it to drive a rack or pushrod steering system, you'd need some sort of torque soak as the sky blue casing will continue to rotate while you corner. This would work like a semi open diff as the soak would create friction between the output axles.

Sounds similar to my mechanical automatic differential lock in principle

[Rudivdk]

On 12/21/2020 at 7:04 PM, Gray Gear said:

using clutch rings is not an option, they have way too much play

 

You could use a sliding (bevel) gear connected to a rod towards the cabin to engage/disengage. But when disengaging the rear steering would be 'free' to turn on itself unless you device some lock. And return to center would be tricky. Something like your safeshift mechanism would be needed, a 'safesteer' maybe?

Indeed as mentioned by other the Claas system is very sophisticated and has the auto-return-to-center function. But it's quite a bulky system, I don't know how much room you have or are willing to give up for it.

Is there a possibility to extend the controls past the gearbox and have the actual steering setup behind the rear axle? That might give you some more space to work with (cover the steering setup with some nitro tanks and you're done...)

[syclone]

Very slim setup, for the decoupling, how about something similar to Nico71's Rally car steering mechanism? Instead of servo input on his, just the input for RWS (mechanism in question shown @ 0:42) Just have an axlepin on the back side of the disk that would lock the rear steering in place when not connected to front steering

 

Edited December 23, 2020 by syclone

[Newest_Tech320]

looks great

[Gray Gear]

Thank you all for your help, this was a really intresting discussion to follow. Now let me introduce you to the solution I came up with:

4 wheel steering enabled

4 wheel steering disabled and rear wheels locked

 

The 4 wheel drive can only be engaged or disengaged when the car is steering more or less straight, so there is no chance to mess up the orientation of the rear wheels.

 

Video to see the system in action:

 

Main issue is the lack of space I have. The system is already a little in the way of where I would normally put the linkages for the 6-speed transmission. I will have to get creative I guess 

 

A special thanks for @syclone who got this stone rolling in the first place!

Edited December 24, 2020 by Gray Gear

[LvdH]

Nice! If you want a solution with just slightly less play you should use these: 

It is just very very slightly thicker but still fits between the knobs. Just tried it for myself, there is almost zero play. In fact, most of it comes from the loose 1/2 pin but you might be able to figure something out with a 3L axle + stud for example   

[Rudivdk]

 cool solution and still pretty small, fits perfectly into a 1:8 model.

I wonder if I can squeeze something like this into a 1:10...

[Bartybum]

Hell yeah I dig it, but shouldn’t the rear axle steer the other way? Or is this car weird

[MinusAndy]

9 hours ago, Bartybum said:

Hell yeah I dig it, but shouldn’t the rear axle steer the other way? Or is this car weird

I think hicas actually steers in different directions to the front wheels depending how fast you’re going? Ie low speed it’s in opposition for tighter turning and agility and when you’re going fast it switches to making it crab slightly.

[Bartybum]

2 hours ago, MinusAndy said:

I think hicas actually steers in different directions to the front wheels depending how fast you’re going? Ie low speed it’s in opposition for tighter turning and agility and when you’re going fast it switches to making it crab slightly.

Well isn’t that curious