[MOC] Group B Inspired Rally Car

[nico71]

A group-B inspired Rally Car, built for the 1/12 competition at the BuWizz Gathering 2025. Features motorized rear drive and steering, suspensions, fake engine, and openable elements.



Specs :
 

• Mixed inspirations from Lancia Delta, Peugeot 205 Turbo, Audi Quatro
• Dimensions : 35 x 18 x 14cm,  Scale ≃ 1/11, Øwheel : 56mm
• Motorized with a BuWizz 2.0
• Drive : 2x RC Buggy Motor (LEGO) (fastest output, 12/28 gear reduction)
• Steering : PFS Servo Motor, Rack and pinion
• Front Suspensions : double wishbones with trailing arms
• Rear Suspensions : double wishbones with floating differential
• Fake engine V6
• Openable doors, hood and trunk

See in action :
 

Design Process :

This model is my third iteration of building a Rally Car from the 90’s, mainly based on my second version (first here). The aim was to rebuilt a smaller version, motorized with BuWizz bricks for the 1/12 Racer competition at the BuWizz 2025 Gathering. So I redesigned completely the chassis and adapted the style of the design with modernize it. You can see the difference underneath below between the V2 from 2016 and the 2025 V3 :




Obviously the motorization take some space, but I redesigned the axles with new parts and smaller width. I reused the principle of floating differential that I used on my Honda S2000, with ball joint on half frame, as I did not have new shorter 4l-cv-join which is also better for torque resistance. The two LEGO RC motor drive a 12t/12t bevel gearing on their fastest output, which goes to the 12t/28t differential. This differential is swappable by 20/28t version, if you want more speed, and the lower output of the RC motor can also be used (two gearing to swap, all included).



The steering is operated by a PFS Servo Motor with rack and pinion and additional linear guide. You can note that the connecting rods are fixed on the knuckles with axle with stop instead of ball joints which are more reliable in case of race contact but with a loss of precision. There is not return to the steering wheel.



The front suspensions are classic double wishbones with additional trailing arms to strengthen the axle and avoid longitudinal movement. The rear are double wishbones with additional springs for the weight, as the BuWizz is located on the back to increase the weight grip.



The fake V6 engine is connected to the drivetrain and is decorated with two turbos and exhaust pipe, revealed by the massive openable trunk/hood. The doors can also be open, revealing a simple interior and the front hood enable mechanical access to the steering.



Speaking of the style, I took a lot of inspiration of various car from the Group B : Audi Quatro for the front and color scheme, Lancia Delta for the proportion, front wheel fans and the Peugeot 205 T16 for the massive wings, completed by a red interior. Most of the ideas come from my previous iteration, but with modernized design with better proportions, including new panels, surface treatments and better seams between the different body panels.




Regarding the performance, with a weight of 1kg and 2x RC motor, it is quite fast (top speed of 5km/h) and responsive but a bit heavy to compet efficiently with smaller car equipped with BuWizz 3.0 and 2x BuWizz motors. 

On the race, I finished at the 7th place, against 12 opponents. With 03:06 of best lap time where winner’s best is 01:15. There was no functional damage, so reliable drivetrain, steering and suspensions. But I modified the front mudguard with a higher one to avoid wheel contact on bump and race contact (parts and instructions also included on that page). I have only one BuWizz cutoff, due to the 2x LEGO RC Buggy motors I used which drain a lot of current. 

So for the next iteration, a BuWizz 3.0 + 2x BuWizz motors, fewer details, less weight, more speed !

Links :

Instructions : https://www.nico71.fr/product/rally-car-v3/

Partlist : https://rebrickable.com/mocs/MOC-259195/Nico71/group-b-rally-car-v3/#parts

 

 

[Aleh]

This can pretend to be a Lego set. For me this look s a way more interesting than the "new" Eclipse & Charger

[TexasEngineer454]

The trailing arms on the front suspension is an interesting solution. I've often noticed on my RC builds the control arms tend to have alot of front/back movement. This would seem to solve that. Your video shows that it still turns pretty sharp. Great job!

[gyenesvi]

Cool looking car, I like the color scheme, and interesting front and rear suspension setups! The only thing I don't like is that the buggy motors are part of the seats :D But that is due to an ethernal problem with the bad shaping buggy/buwizz motors; impossible to place them so that they aren't in the way somewhere in models of such size..

[TLCB]

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