Simple high-performance model built for off-road speeding. Features RWD propulsion system and long-travel suspension. Building instruction for its chassis is available in the Downloads section.
Completion date: 23/11/2013
Power: electric (RC unit)
Dimensions: length 45 studs / width 29 studs / height 24 studs (not including antennae)
Weight: 1.127 kg
Suspension: front – independent / read – dragged axle
Propulsion: 2 x RC motor geared 1:1
Motors: 2 x RC motor
Top speed: 12.6 kmph
The building instruction for the model’s chassis is available here.
This model was put together in a total of 6 hours, simply because I wanted to put the new suspension arms from the 42021 Snowmobile set to test, and because I was interested in how much speed I can get from two RC motors rather than four. It was ugly and it looked nothing like a proper trophy truck, but its performance has far surpassed all my expectations.
Typical trophy trucks are by definition the fastest off-road vehicles in existence. Their relatively low weight coupled with powerful engines (reaching well over 700 HP of power) makes them spend a lot of time in air, thus requiring robust and long-travel suspension systems. Their front suspensions are particularly characteristic as they employ extra-long suspension arms.
I have built a chassis that had all the characteristics of a regular trophy truck while being extremely robust, then put some crude body on top of it, basically trying to keep the weight low. Interestingly, the weight could not be too low, because when it was less than 1 kg, the traction on rear wheels was so poor that the chassis tended to spin uncontrollably due to the lack of a differential.
The performance of the model is best seen on the video below. The suspension turned out to work phenomenally, with the 9-studs long suspension arms and vertical shock absorbers, in front and the single axle built around the RC motors in the back, capable of going up and down, but also having enough backlash to tilt left and right slightly. It was robust enough to withstand jumps from any height and onto any surface, driving around in mud and water (luckily the wheels were set too far apart to splash the RC unit in the middle) and it was easily fixed after numerous collisions. The combination of weight, power, traction, suspension softness and steering lock was splendid – while the model’s acceleration wasn’t too high, its stability, its speed and the way its steering system reacted provided the best driving experience I’ve ever had with a Lego model up to this date. And the final weight was exactly right to make the model spin only intentionally and never by chance.
I feel the model has achieved all the important goals, despite its evident ugliness. It was extremely fun to drive, it sustained literally zero damage after all I put it through, and I’ve had tons of fun working on the video.