[MOC] Nissan GTR with EV3

[TheMindGarage]

This is my first MOC on this site! Bear in mind that I have only been building for slightly more than 2 years and don't have a very large collection, so my builds aren't exactly Sheepo standard...

The car is a 1:10 model, although I had to deviate from the scale slightly in order to fit the functionality I wanted into the car (width was increased to 25 studs for example). Here are the features (LONG list):

• Remote control drive with three EV3 Large motors. Top speed around 5mph. Drive goes to all four wheels via two diffs.
  
• Remote-control steering with EV3 Medium motor. Turning radius is rather large though.
  
• 8-speed automatic hybrid gearbox. Basically a 4-speed automatic and a 2-speed ratchet gearbox (inspired by Sariel) used together.
  
• A model piston engine (V6) in the front with engine capacity scaled to the real car (I measured mine at 3.77cc, real car is 3.8l).
  
• Lever in cabin with Drive/Neutral/Brake settings.
  
• Handbrake system and rear friction brakes.
  
• Full independent suspension with negative camber angle.
  
• Adjustable ride height for each wheel through tuning dials (front ones are under the hood, rear ones are hidden next to the spoiler).
  
• Adjustable castor angle for each of the front wheels (adjusted by rotating the turntables).
  
• Opening sprung doors with locks.
  
• Opening sprung front hood.
  
• Cabin with fake steering wheel (non-rotating), FOUR SEATS and a floor.
  

Pic with doors and hood open, revealing the model engine. The red pads on the hood are rubber friction pads (from EV3 Education Expansion set) - these keep the hood closed.

Close ups showing the piston engine and suspension. When the tuning screws are turned, a worm gear system rotates the arm where the shock absorbers are mounted. Adjustment range is about 2 studs. Castor is adjusted by turning the turntables - this effectively rotates the entire suspension system relative to the chassis. Beams from the chassis are placed to interfere with the rotation of the turntables - this keeps the turntables in place when not adjusted.

The cabin is fitted with a full set of 4 seats, as in the real car. The occupants of the rear seat are given the rare treat of having gears from the 2-speed ratchet gearbox right next to them.

When the drive setting is enabled, a driving ring allows the motors to drive the 4-speed gearbox. In neutral, the driving ring meshes with nothing, letting the car roll freely. In Handbrake, the driving ring locks the input shaft of the 4-speed gearbox to the output using a gear ratio that isn't part of the gearbox, effectively locking the shaft. This is like solving the equation 3x=x (x is the rotation speed of the shaft) - x can only be zero.

Part of the drivetrain is shown here. The differential and elastic system measures the resistance on the input. The system on the bottom-left shifts gears when the resistance is too low or high. The 4-speed gearbox is a standard 5/3/1.67/1 design - the 2-speed's gear ratios fit "in between" these.

Notice the towball links and lever below (remember this is an upside-down view) the gearbox. Those control the rear brakes. In Handbrake mode, the brakes are engaged.

Here is a graph showing the 8 power bands (created with Microsoft Excel). The lines are cut off when the spreadsheet calculates that the motors run out of torque. This graph used data from my test runs, so the performance shown here is similar to that in real life.

Top view of the rear with the body removed. The drive motors are visible, and the 16-tooth gears (used as tuning dials for the rear suspension) can be seen.

This is the underside of the rear axle. When the towball link is pulled, the red rubber pad swings outwards and grips the inside of the wheel.

I made the rather radical decision to leave the EV3 brick exposed at the back. I decided that covering it up would require too many parts, add too much weight and deviate from the scale. The GTR's four red rear lights are modelled with new-type 16-tooth clutch gears.

Overall, I think this has been a successful build for me, cramming in far more features than any of my prior builds (in fact, I am yet to see a 1:10 supercar model with more functionality). However, some things could have been improved:

• It isn't a perfect scale mode. The seats are way too far forward - I had to do this to fit the monstrous powertrain inside.
  
• The rear end aesthetic requires, well, some getting used to.
  
• Rear wheels sometimes rub against the top of their fenders. Can be solved by setting the tuning to maximum ride-height.
  
• Negative camber angle is too pronounced.
  
• Steering lock is very small, and gets even smaller if castor angle is set to extremes.
  
• Gearbox tends to be rather "reluctant" to shift gear - this was the only way to stop it from constantly alternating between two gears.
  
• It isn't exactly GTR like when driven. GTRs are known for their acceleration, but the model takes ages to get up to speed. It drives more like a truck.
  

My next build will be my Porsche competition entry - no EV3 will be involved for that, although plenty more features (did someone mention 4-wheel steering?)...

Edited July 6, 2016 by TheMindGarage

[Victor Imaginator]

Wow, automatic 8 speed gearbox! And turntables for adjusting caster angle. And 5mph max speed. And other nice features. Yes, it doesn't looks like Sheepo's models, as you said, but for me it's just different approach. And if you say Nissan, I see it's a GTR R35. Using something larger red for outer pair of rear lights will make model even more recognizable. I like it)

[Jurss]

I don't recognize there any specific car model, but functinality is interesting.

[AkiyamaWataru]

I don't recognize there any specific car model, but functinality is interesting.

I have the same problem. I can recognize the taillights but thats it. The front doesn't resemble a GTR as it does not have a 'mono grill'

[Victor Imaginator]

Part of front bumper painted black on R35 GTR's, so it looks like mono grille.

Edited July 7, 2016 by Victor Imaginator

[AkiyamaWataru]

It might be black. but There are openings. i would like to see them modelled and not just as black beams.