[MOC] 42099 C model Buggy

[gyenesvi]

Hi,

I'd like to share my second C model for 42099, inspired by the recently released off-road buggy.

The design goals were 1) faster speed 2) responsive and long suspension travel 3) lightweight and curved shape.

The wheel hubs and the differentials perform down-gearing, so I decided to apply 3x up-gearing by a ratio of 5:3 and skip the differential to make it faster than the original. Since the differentials are not used, the small gears can be used for up-gearing with perpendicular meshing of gears, which is smoother than the parallel meshing of the 20 and 12-tooth gears. I decided to use rear wheel drive only, one motor driving each rear wheel. I managed to compact the drive-train with the following setup:

For suspension, I wanted a long travel and a wider wheel base, so I tried to increase the length of the swing-arms. The rear suspension seemed simple with 7L beams, but the front suspension was more difficult, as I had to increase the length of the 6L steering arms in the set by 1 stud, so I had to apply some tricky workarounds. Furthermore, I wanted a lightweight axle with a positive caster angle, with the steering motor integrated closely to the axle. The result has more than 6 studs of ground clearance and 3 studs of travel and is quite responsive:

The battery is integrated into the middle of the model to distribute the weight between the two axles, and to provide easy access from the bottom. The whole base looks like this:

The bodywork proved to be the most difficult to get right, since the panels available in the model are hard to use to get the light-weight frame-like body that I wanted. After taking some inspiration from the shape of Madoca's Blue Lightning buggy, I got the hang of using the arched pieces and the flexible hoses to build the curves, and used some of the panels to finish the body with a simple roof and hood. The roof is attached very strongly to the base, so the car can be lifted by it.

As the small grey seats in the original just didn't feel like a match to the overall shape and scale of the model, I gave building a custom seat a try. Luckily, the few available red pieces were just enough to make a black seat with two red stripes :) I think it adds a lot to the overall look of the model.

Here are a few more pics:

 

Finally, here's a video of it in action:

 

Building instructions available on Rebrickable.

Let me know how you like it!

Cheers,

Viktor

Edited February 7, 2021 by gyenesvi