We talk about off-roading a decent bit here on the Autopian. David and I both like to indulge in cheap vehicles that we take far off of the beaten path, and we sometimes take off-road beasts on drives around the country. These have off-road kit to keep them going when the terrain gets tough, but it can sometimes be hard to visualize how something like a locking differential helps a vehicle out of trouble. A YouTuber has found a brilliant way to demonstrate off-roading with a Lego vehicle that grows up into an elaborate machine.
Over the years, you’ve likely seen us demonstrate what some off-road vehicles can do when the going gets tough. Last year, David and I took his $700 Chevrolet Tracker and my $1,700 Volkswagen Touareg to an off-road park and proving ground used by some automakers.
Both 4x4s are very different; my Touareg has limited-slip differentials, permanent four-wheel-drive, low-range, and was available with a locking rear differential. On the technology side, I have hill descent control, off-road traction control, and off-road ABS. Meanwhile, David’s was old-school with part-time four-wheel-drive and that’s about it. Both SUVs gave a beastly performance, but we perhaps didn’t really get to demonstrate why our rigs did so well.
YouTube channel Brick Technology recently uploaded a video that shows how some off-road parts do their job. In it, the channel starts off with a simple sled with narrow tires and doesn’t even have steering then tries to get it to complete a sandy course. As the YouTuber makes changes to overcome challenges, it evolves into a 6×6 truck, check it out:
I’m not going to go through every single frame of this video, but instead just what might be the most important to you out there. The host starts off with what’s more or less a sled. It’s rear-wheel-drive with skinny street-style tires and most of its weight toward the front.
It immediately digs into the sand, getting stuck.
Moving weight more to the rear didn’t fix the issue, but giving the sled wider tires allowed it to complete the course without getting stuck.
For the first upgrade, the sled got a steering system and an open differential. The vehicle made it about halfway through the course before it got stuck with a single wheel helplessly spinning. This is the work of an open differential. These allow drive wheels to turn at different speeds. The result is great for driving on pavement, where you don’t want to drag your tires through turns. However, since open diffs cannot bias torque, they can be a pain off-road as shown here.
To fix this, the YouTuber throws on a differential lock, which helps by locking the wheels of an axle together, making them spin at the same speed. Now it finishes the course without issue. Some vehicles with limited-slip or open differentials may use a traction control system as an aid.
My Volkswagen Touareg did not come with the optional rear locker. However, it tries to make up for it by using the brakes to lock up a loose spinning wheel, diverting power to the wheel with traction. Oh heck, now’s a great time to pull out this excellent explainer on differentials:
Next, the YouTube channel simulates what many of you probably already do during the winter. The sled–which now resembles a lunar rover–starts off with some weight in the middle and it gets stuck. With the weight moved to just above the drive wheels, it’s able to complete the course. The addition of even more weight makes it get stuck again as the vehicle’s bottom scrapes the sand. Thus, the next upgrade is ground clearance, which allows the sled to finish the course.
Continuing the test, the rig topples over trying to go around a curve, which gets fixed with wider off-road-style tires. The vehicle passes, just for the motor’s gear to fail with more weight added on. The YouTuber rebuilds the vehicle, giving it four-wheel-drive. Now it can complete the course without breaking any gears.
Moving on, the channel gives us another demonstration of a locking differential in action when the vehicle, set to RWD, gets stuck. With the flip of a switch, the differential locks and both wheels push the vehicle through.
With the vehicle a beast at moving on a flat surface, Brick Technology now changes the course by adding deep pits for the 4×4 Lego flatbed to drive through. It gets stuck, even when weight is shifted. Here, the channel is showing what happens when a locking rear differential may not be enough. Brick Technology adds a locking front differential, which allows the vehicle to plow its way through until it high-sides trying to get through the pits.
That obstacle calls for an elaborate redesign which adds a suspension with some good articulation. Check it out:
After adding wider, more squared tires, the vehicle basically becomes unstoppable at getting through the course, which now means it’s time to change the course. As a final challenge, the vehicle must now complete the course while driving on a slope. It fails and Brick Technology’s response is to make it six-wheel-drive.
Now, the vehicle is complete and the build is finished off with a body that gives it some serious Mercedes Unimog vibes.
Of course, the video isn’t a perfect representation of how things work in the real world with a real car. Usually, when you find the limits of a rear-wheel-drive vehicle off-road you’re probably going to be spinning your tires stuck, not grenading your transmission. And obviously, the use of Lego parts also doesn’t make for a perfect representation of the hardware on an off-roader. Despite that, we think this video does a good job at showing at illustrating the use of equipment that some of you probably already have today. Plus, it’s just good fun watching complex Lego creations get built.
We recommend watching this video in full because it’s a good time. The whole channel is a fun watch! I didn’t know that you could build air-powered Lego engines, but this channel has it.
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