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  1. I had many people ask me in the Wildcat 6x6 topic and it's video if I really need 12 motors, couldn't I get simillar performance with a lighter model? So in order to test and showcase my reasoning I built this very simple 4x4, it uses only 555 parts and is powered by "only" 2 motors: Originally the driveline and gear ratio was as following: Motor's fast outputs to the 2 speed gearbox - 12 tooth bevel gears - via cardan joints to the planetary hubs But than I soon noticed the model lacked sufficient torque, especially in high gear, so I changed the driveline to the following: Motor's fast outputs to the 2 speed gearbox - 20:28 normal differential - via small CV joints to the planetary hubs This driveline ended up having a very simillar gear ratio as the Wildcat 6x6, I think it's some 3% faster, which is negliable IMO. One thing that I did have to do is lubricate the main drive axle, as it was prone to melting in high gear: Because this light 4x4 has open differentials, the front suspension was designed in such a way that it imitatates a pendular front axle by having shock absorbers on a pivot. This allows the front axle to basically act like a pendular axle, easily adjusting to the terrain amd keeping the weight even on both left and right side. So...What about the results? Well, the outdoor test showed that the model performs good in low gear, it has plenty of torque to climb and works really smooth and efficient. But where it lacked was in high gear. While it did reach 15 km/h as the Wildcat 6x6, the acceleration itself was much lower and both motors were drawing a lot of current. Any prologned steering in high gear at full power caused the motors to overheat and cut out, no powersliding on gravel like the Wildcat 6x6. Also when driving on the pump track, it was able to go over big hills in high gear, but it was lacking the speed to actually get significant air, again unlike the Wildcat 6x6. So... Why does it seem more motors and a heavier model is preferable? The answer comes to one factor - Power To Weight ratio: Wildcat 6x6 uses 12 drive motors and weighs around 2,5 kg - this means each motor has to move around 208 grams of weight This light 4x4 offroader uses 2 drive motors weighs around 0,8 kg - in this case each motor has to deal with 400 grams of weight, almost double of the Wildcat 6x6 So does that mean bigger is always better? Well when it comes to math, it seems to point that way. But bigger and heavier models suffer from another problem - the Inverse Cube Law. Basically a bigger model needs more structural reinforcments to hold itself together which means it's heavier and therefore needs more power, etc... It's a typical problem in aviation and rocket science. In our case, a bigger model if built efficiently (using frames and such for a light, strong chassis) will generally perform better, but it will also cause a greater load on the individual parts such as suspension components and wheels in the case of my Wildcat 6x6 (when going to quickly over a large bump, the front wheels have a tendency to fall off to to the higher forces in relation to higher weight). So what's the take from all this? I would summarize it like this: If you want a robust, reliable model go light and slower If you want a very high performance model, pack it full of motors, though individual components may suffer more and fail under their own weight. Also remember there are some heavy elements such as steering motor, wheels, tyres, hubs that you will have to use regardless of the number of drive motors - which weight favours being spread among more motors And also that some components such as planetary hubs do come with some inherent friction that will have to be overcome - which again favour it's friction being spread among more drive motors. I'd love to to hear your opinion about this. Also if anyone is interested, i can make a seperate topic/video about the Light 4x4 offroader.