Alan takes on the 4×4 X-treme Off-Roader
Alan has been working steadily through the library and the 42099 landed with him earlier in the year. It is the set people ask about most when they see the fleet. The four big 107 mm tyres catch the eye immediately, and the fact it is app-controlled puts it in a different category to most of what we carry.
This was one of the first sets LEGO released under the Control+ banner back in 2019. Two XL motors drive the axles, an L motor steers, a Smart Hub (battery box and receiver in one) sits in the rear bed, and the whole thing connects to the LEGO TECHNIC Control+ app over Bluetooth. You get steering, variable speed, and tilt gauges in the app that warn you past 30 degrees. Alan’s photos below show a different kit, the Arctic Truck 42038, built over a few sessions; the notes on this page are about the 42099.
The drivetrain is what makes this build worthwhile. Each axle is its own unit, with its own XL motor, its own differential and a planetary reduction inside each wheel hub, and the two are joined through a pair of turntables so the front can roll against the rear. When you lay the main frame on the table and start attaching them one at a time, you understand where the money went: the electronics, more than the 958 pieces, set the price.
The build sequence is logical enough, but the Control+ integration means you are fitting electronic components through the process rather than at the end. The Smart Hub goes in before the body and you have to route the motor cables as you build the body around them. It is not difficult but it requires a bit of patience to keep things tidy inside.
The Control+ app is not just a gimmick on this one. Proportional steering through the touch controls feels more satisfying than a physical knob on a smaller set, and the one-touch mode, where you tap where you want it to go and it drives there, is good fun in motion. If there are children around, this holds their attention considerably longer than a manually operated model.
I think the 42099 is one of the better arguments for app control in the Technic range. Some sets where the app is the main selling point end up feeling like the build was an afterthought. This one is not that. The chassis is solid, the planetary wheel hubs are well engineered, and the app control adds something rather than replacing something.
If you are a Brick Club member and you have been photographing your build, track your build progress and upload your photos in your members build account. It is good to see how different people approach the same kit.
Alan has a good eye for the mechanical bit of a Technic build, and the 42099 gives you plenty to look at before the body is finished. The app-control side gets the attention, but the real interest is how the drive modules and suspension make the finished model feel like a crawler rather than a display truck.
I like seeing this one in member photos because it is not neat in the usual supercar way. It is squat, odd, and built to move. That is a useful change of pace in a library that has a lot of polished cars.
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