Mini AWD Trophy Truck

[Zerobricks]

This is a small AWD Trophy truck that I was able to build thanks to the new components in the Skyline, specifically the 4L links and the 4L CVs:

The biggest challenge with this model was in finding a solution for the FWD which would allow for high suspension travel and a good steering angle while being limited to 25 degrees of movement of the CV joints.

I decided to bring the front suspension arms closer together, therebye creating the following suspension geometry which forces the front wheels to move in an arc:

This in turn has several advantages:

1. Reduces the angle the CV joint has to carry the power on the outboard side
2. Allows for a higher steering angle
3. Increaces the ground clearance on the bottom

As such the front suspension is supported by 2 soft shock absorbers. Notice how the L liftarms hold the suspension together, supported by a white bar that goes through the cross hole:

The rear suspension uses the normal equal length parallel arm design and it's supported by a combination of a hard and soft shock absorber which are placed at an angle to simulate a progressive setup:

 

The front axle also uses double steering rack simillar to 42160 with 4 steering links to keep the front steering system as accurate, robust and stiff as possible (Please note, there are no 4L link yet available in LDD):

Originally the driveline used a 12:20 gearing from the motor to the main shaft and than the 20:28 to the wheels.

I used a couple of bevel 20 tooth gears so that a 5x11 panel could fit under them to protect the gears.

But during video shoot, the solution proved to be a weak point, so I redesigned the driveline to use a pair of 16 tooth gears and a 12:28 diff combo which gives me the same gear ratio, yet with added strength:

The only weakpoint left were the small CV recepticles:

But after reducing the current limtiters from 2 to 1.5 A, I have yet to suffer a failure, even when suddenly changing directions.

 

You can see the model in action here:

I have to say this is a really compact, fun and almost indestructible model and I'm really happy how it turned out. Now if only LEGO could come up with a 4L version of the large CV joints...

Edited August 11 by Zerobricks

[1gor]

I saw YouTube video today and must admit that it is very cool little trophy truck. Years ago I was thinking about something like that to implement my buggy motor but there were no short enough suspension arms available...yes, we defenefelly need stronger CV joint with less slack one stude wide; new stronger CV joints are sometimes to big and don't fit 1 stud wide space...

 

Edited August 11 by 1gor

[Zerobricks]

Thank you for the praise, Igor. Indeed sometimes I wish LEGO would keep the large CV geometry, but in smaller package which would still fit in the standard 8 mm grid. Regarding the model itself, I think it might actually see some action on the next year's BuWizz gathering!

[1gor]

As time passes by, I have decuded to keep my Lego indoors, because now due to crashing and several times wires got stucked I have 5 PF servos for resoldering... it is ultimate test for Moc in natural environment and when that test is passed than it is construction thay belongs in ultimate class.

...just one more thing; IMHO of all differential options red ones (with 12 tooth gear) have highest redistance and Daytona difs are the smoothests (only buggy motors are extremelly fast...)

kind regards

Edited August 12 by 1gor

[SNIPE]

If only we could have an axle of say 3 or 4L but have some sort of part on both ends of the axle that fits loosley or pops into the audi wheel hubs/reinforced short CV joints. 

Maybe if I did a search for "." in LDCAD while having the unofficial, official, digital-bricks , and other parts libraries installed, there might be a psrt there that fits my description (probably a system piece).

The 8 tooth gear works but you cant have steering or suspension on the axle then.

Same story with putting the old female CV joint into the female Reinforced CV joint. It works, but no steering or suspension.

I once tried with a 1x1 flower plate/brick with 4 petals but it didn't fit and doesn't have an axle hole.

Edited August 12 by SNIPE

[Zerobricks]

1 hour ago, 1gor said:

...just one more thing; IMHO of all differential options red ones (with 12 tooth gear) have highest redistance and Daytona difs are the smoothests (only buggy motors are extremelly fast...)

kind regards

It makes sense, since the red one has the highest gear ratio, the drive axle has to do more turns, resulting in more friction. Also, the bigger the gears the less force acts on them at the sae torque level, reducing friction.

Edited August 12 by Zerobricks

[N1K0L4]

Awesome model as always from you :)

I want to add on my YT comment on changing to yellow diffs. As you said the torque limiting factor are the female CV joints and because of that you limited the current to 1.5A.

If you change to yellow diffs that would reduce torque by 48%. That means (if torque goes lineary with current) that you could increase max. current to 2.22A max. and get the same torque for with more speed.

It would certainly reduce the runtime if you drive it on full power, but I think 2A current limit would be more than enough for this model as it's not a crawler. 

(Why I'm saying all this: I wanted to see it fly :D )

[gyenesvi]

Really nice build, I love the small scale, the electronics is powerful enough for this scale, and it's not too much for the plastic either. The suspension setup is very clever at the front, you are too fast testing out these new parts, but that was expected :) And the overall looks is also really nice, flows well with the available parts!

[Jerry LEGO Creations]

Really cool build, great use of the new suspension parts! I'm curious to see what they will bring, having proper suspension on smaller models is really nice to have 

[Krxlion]

As guys were saying above - clever build, and interesting techniques. I have already commented your YouTube video, and thank you for the response. It's cool to have someone like Zerobricks to test all the new parts under Buwizz power, haha. :D

[damian_kane_iv]

I really like this design and the suspension! Especially that its AWD