Posted January 9, 20241 yr I like to try and make lego rc cars (with motors and technic peices) but this time there is a problem with the front wheels, i dont know if it needs a differential or something but there is a problem, every time i put the motor in one of my 3 gears in the small makeshift gearbox comes out and leaves the one on the other side on its own, for example if the box is looking like this to start : |_| with one on each side once i try to go forward it ends up like this \_| and that gear on the left goes out of its place, because of this the car (which is meant to go forward) goes in the direction of the gear which is actually in place so in this case the car can only go right, but if press the backwards button it takes that right gar out a places the left one back in making it go left , so its like an unwanted turning system (that only turns). it does not happen when i lift the car of the ground and turn on the motor, but once the wheels touch it just moves a gear out of place. how do i fix this? some people say i need to build a strong frame around it, some say i need a differential, what do i really have to do? Edited January 9, 20241 yr by ilovemakinglegorcraceonyt
January 9, 20241 yr Without pics it's hard to see the problem... Or try to upload them here: https://imgbb.com/
January 9, 20241 yr Author oh sorry, i did not know the picture was not available hopefully this should work now https://ibb.co/ByBYxV9https://ibb.co/qJmD7Zbhttps://ibb.co/kqKxndshttps://ibb.co/hFswS0M the first link is of what it looks like normally and the next three are pictures of the misplaced gear this makes it turn right only because the left gear is not there to make the straight driving work because all 3 equal gears are not there it happens every time i try to controll the car with the motor to go forward i have to place the gear back and everything, theen it just happens again, i can only turn right forward if i use the forward button, and left forward if i use the backwards button (which is supposed to also go forward, i dont know why there is a backwards button)
January 9, 20241 yr The biggest problem you have with that system is that the two wheels are currently rotating in opposite directions. You only need one bevel gear on the output, so you should start by combining the left and right sides into one solid axle, with only one gear. Eventually you'll probably also want to build some braces around the axles to keep them from bending forward/backward, but you should start by fixing that gearing
January 9, 20241 yr Author hey thanks so much, does anyone here maybe have a video that could help me or introduce me to this subject because im new to gears and things, Thank you! And does anyone else have an idea that could help this? also do i need a differntial?
January 9, 20241 yr 35 minutes ago, ilovemakinglegorcraceonyt said: hey thanks so much, does anyone here maybe have a video that could help me or introduce me to this subject because im new to gears and things, Thank you! And does anyone else have an idea that could help this? also do i need a differntial? I'm not sure about videos (you could definitely take a look for yourself), but a good book for learning Technic stuff is The Unofficial Lego Technic Builder's Guide. A differential would typically be used there on a real car, but because Lego cars are fairly light, you can definitely get away without one. It does affect the handling a bit, but it's not necessary
January 9, 20241 yr What you’ve got there isn’t a differential. As others have said what you’re doing there is trying to turn each wheel in different directions. If you look as official models with a differential you’ll see how they work. For the scale and speed of your model I don’t think it’ll need a differential so I’d just use a single drive gear on an axle connecting both wheels. heres a video about differentials
January 9, 20241 yr You don't have to have a differential. You do have to support your driving axles though. Might be worth buying some more complex sets to see how Lego do it. Alternatively Lego host all their official instructions on their website, so you could browse those to see how they build axles. For the size of car you are producing, I'd suggest some of the trucks such as 42112 or 42128 for a guide on how to build a powered axle. These sets take drive from the wheels to power functions on the vehicle rather than being motorised like you are doing, but the principles are the same whichever direction power is going.
January 9, 20241 yr I don't even ask how you put those stop axles into the fork piece. Pro tip: if you have to bend pieces to put them together, you're probably doing something wrong.. Yeah, that Technic Builder's Guide book quoted above sounds like a good way to start learning. Or just a lot of youtube videos about how to build technic stuff. 3 hours ago, Maaboo the Witch said: Hosting images on Flickr and embedding them here would help immeasurably. Anybody noticed that every newcomer's threads start with somebody teaching them about how to embed images? Great to see some people are more patient about that!
January 9, 20241 yr 10 minutes ago, gyenesvi said: I don't even ask how you put those stop axles into the fork piece. Hehe, I'm guilty on that one! Usually with 5Ls, but it can be pretty handy sometimes! 8 minutes ago, ilovemakinglegorcraceonyt said: Do all these tips still work if I am using a motor? Yup!
January 9, 20241 yr 3 minutes ago, 2GodBDGlory said: Hehe, I'm guilty on that one! Usually with 5Ls, but it can be pretty handy sometimes! Why am I not even surprised.. :) 14 minutes ago, ilovemakinglegorcraceonyt said: Do all these tips still work if I am using a motor? Yeah, even if you are using a motor, don't bend the pieces.. :D
January 9, 20241 yr Author Also can somebody provide a picture of an example because I am just not getting this?
January 9, 20241 yr It should be ok with this if your vehicle is light enough. this is not a differential though. Maybe before trying to motorize a mechanism, try it with your hands and see if it works as intended. What you did obviously turns one wheel forward and the other one backward. Edited January 9, 20241 yr by JoKo
January 9, 20241 yr 6 minutes ago, ilovemakinglegorcraceonyt said: That. Worked. Splendid thank you so much joko You're welcome! And welcome on the eurobricks Technic zone btw
January 10, 20241 yr It seems to me the OP is just starting their LEGO Technic building career. Not so long ago I also just started and I often asked questions that were common knowledge to most others. My advice is to spend more time actually building sets, no substitute for experience. Often times while building sets, I will experiment with alternative ways of assembly, while simultaneously generating many great ideas and several not so great ideas. Remember failure can be a learning experience. As others have said, start with something very simple and go from there. It is my experience that if I spend all my time designing and building the biggest, baddest most elaborate design, I inevitably never actually finish or get to enjoy the model, as I become quickly overwhelmed. So try to keep your designs simple at first, with experience your models will greatly improve and you will be much less frustrated.
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