gyenesvi

So you mean instead of having slight shade variations, they choose to create complete color inconsistencies? I don't think it has to do anything with it. Rather they just try to save production of that part in certain colors, making models look even more patchy than it already is necessary due to technic parts' shapes.

Oh, right, that was my next guess, there's a beam behind it that it connects to. It's a pity that they often decide not to produce that part in many basic colors, it is so ubiquitous, used all over the place, and often causes color inconsistencies. Not sure why they have to be cheap about that one (for example, they did not have them in orange for long, the Ford Raptor did not have them, but finally they got reintroduced).

To me it sucks even more that some connectors are not available in green, and hence they replaced them with black, creating random color discontinuities like on the doors and the door hinges. I wonder what is happening at the top of the door where a 2L green connector plus a 1L black beam? is used instead of a 3L green connector? Or is that black piece not a 1L beam?

Thanks for the good questions! There are a couple of reasons for the difference, mainly to make the rear one space efficient. The key limiting factor is the CV joint in the drivetrain, the length of that is fixed. With this setup on the rear, it is enough to have only 1 CV joint, while in the front it has 2 CV joints, saving 3 studs of space longitudinally. The single U-joint results in a positive caster for the rear axle, which is acceptable, but in the front it would mean a large negative caster, which would be bad, both for the suspension and the steering geometry. So in the rear as the axle is not parallel to the chassis and the caster changes upon articulation, you cannot have two more links. This setup is like the lego ball-joint setup, but without the ball-joint itself, as that would take up too much space to fit in due to its limited connections. In the front, you must have a proper 4-link suspension to have good geometry, and also to allow linkage based steering. The Panhard rods don't limit the flex, they are designed to be as low as possible to also not result in side-to side movement or bump steering (it is parallel to the steering link). In the rear it is actually essential to minimize the side-to-side wobbling, because of the single CV-joint setup, that cannot follow side-to-side movement, and side-to-side movement would put friction on the driveshaft. I think however that this setup only works well in a smaller, lighter build, and at slower speeds I guess. For bigger heavier models you'd have more space longitudinally and you could add another CV-joint to the rear as well. You can see more images of similar axles in my other thread about the different small chassis variations, they share the same concept. Another good property of this rear setup is that the springs are positioned much lower than in the front, that keeps the rear bed clean, where the battery hub needs to be placed (which can be a problem for bigger battery hubs like the Technic one), otherwise the springs would end up colliding with it.

That's what I wanted to ask as well. Maybe better in the Liebherr thread. Well I agree that it was not needed neither in the Ferrari nor in the skidder, but that does not automatically conclude that it was designed for the Liebherr crane. My guess was that it would be required for a faster RC car, like the upcoming Audi (if that's motorized), because for slower stuff, the red one would work as well.

That's an interesting proposal, never heard that before. Where do you get that from? It isn't unbelievable, but I guess that would mean that the drivetrain is fundamentally different from that of the Liebherr excavator and the Cat dozer (even though the Cat did have a differential, it did not have to take significant load as it was only for driving the fake engine). So I guess a heavy duty differential would only make sense if the drivetrain would be more sophisticated, for example using an adder mechanism, like in reality. But that would mean that one motor would be used for drive, and one for steering, which would put a lot of stress on that one motor and the drivetrain for such a huge model. So I am curious how that could work out.

The guys before you just concluded that it is indeed the crankshaft, and not a part that fell off, an I think they are right. It's not hitting the beam, it just appear so due to the perspective.

I have to admit it took me quite some time to read through this long writeup, but it is really deatailed and informative, thanks! Great that you shared all the difficulties about dealing with things at higher speed, apart from melting parts, such as proper suspension geometry. Nice testing methodology to keep improving your build! And the result is pretty convincing, congrats! It is true that sometimes I am dreaming of such components being available to be able to build cars with realistic suspension and drivetrain setup. It is a pity for example that such a trivial motor setup that you have there is hard to achieve in itself due to the sizes of the motors, not to mention the very weak performance if that would be built from lego components. Btw, I like the crawler setup you have there, I recently bought such tires and I am eager to test them in a future project. Cheers!

Thanks! Yeah, the rear clearance is a bit small for the articulation, but with the custom tires it does not matter, it does not get stuck in the fender even when it touches it (the lego buggy tire can get stuck a bit unfortunately). But I did not want to change that part because it's clean and simple this way, plus the real one does not seem to have more clearance either.

Oh, okay, thanks, I get it now, so you only need to switch what the left/right sides are doing wrt each other, and that can happen inside the body, that's nice and simple!

This seems pretty interestinng technically with the proper suspension and the steering modes. I always wanted to build such a suspension! The steering modes are shown to be selected by the lever in the middle of the body. So does that mean the front and rear wheels need to be actuated independently and the big turntables are used such that two functions could be transferred through them?

I don't think there is a more recent link than this, I saw his build in the Buwizz camp in person. But as a start you can simply swap the inner CV joint to a U-joint, it is the same length, only the flex point will be different but that does not matter as the axle is a solid one. Then with the U-joint in, it is possible to use different drive axle lengths, so it becomes possible to make the whole axle wider if one wants, but maybe for your build you just want to keep it narrow.

Thanks guys! Indeed it feels a bit better with BC app, but I think it is a big difference to use these motors with rack based steering vs linkage based steering, because the way the link lengths need to be set up vs the gear size, the link based steering may require 2-3x more power (simple physiscs). With gear rack based steering it also works fine for me, but it is simpler and more realistic with linkage based steering for live axles.

Actually Attika did the same, his latest version is with U-joints and I think it works fine :) But obviously it would depend on the weight of the whole model.

I don't really get this problem either, what do you mean by longer arms? A wider axle? Of course that would be required. The set 42110 has IFS/IRS because the real new Land Rover has that, so simple. @Teo LEGO Technic, the design of Attika is even more angled than mine and it has 1 stud more ground clearance!!

Indeed, I was about to suggest the same. At least this is how I will want to build and test a trial truck myself at some point :)

Hi Guys, Let me present my latest model, this time a smaller build: an RC Toyota FJ40. It started out as an experiment with motorization of my manual Toyota FJ40 alternate of the Ford Raptor set, but over time it grew to a fairly independent project. Interestingly the resulting model is simple but versatile one, that is buildable both with PF and PU electronics, basically with any kind of power source / controller. I like the FJ40, especially the open version without a top and doors, something like this one, and I love this dark gray color: Unfortunately, some key panels for making the hood were not available for a long time, so I did not start working on it, but in the meantime I though I'd do it in orange after the manual version. And luckily, the Peugeot hypercar was just announced recently in DBG, bringing the required panels, so now it will even be buildable in this color :) So first I started thinking of a possible motorization. I started with PU electronics, but soon realized that PF motors could just work out better here, and since I was interested in testing and comparing them anyway, I gave it a go. For example for the steering, I wanted to test out the old PF servo's strength. In the end I built a PU version as well to make a comparison. Glad I did so, because I did get some interesting results! Features: - all wheel drive with 2-speed manual gearbox (2x L motor for drive, servo for steering), good speed and torque - live axle suspension on both axles, 4-links + Panhard rod at the front, 2-links + Panhard rod at the back, soft articulation - working steering wheel with good amount of turns - openable doors, hood and trunk, foldable windshield - removable and swappable doors, modular bodywork Chassis As often for off-roaders, I wanted to build a sturdy drivetrain with planetary hubs and new CV joints. After my Bronco build, the 'L motors on the floor with a gearbox in between' layout seemed like a good idea to use again, but this model was slightly smaller scale than the Bronco, requiring a shorter chassis. That's where the PF L motors started to come in mind, as the length of the PF L motors is only 7L, which is just perfect for sandwiching a gearbox between them as the length of the gearbox is also 7L, which is important if one wants to build only using new CV joints, because that length cannot be changed due to the fixed axle length of the CV joint. The 8L PU L motors can be hacked in, but then they would be in the way for the mounting points for the rear suspension links, so those have to be moved back 1 stud, which would result in slightly misaligned geometry (wrt the CV joint's pivot point). No big deal, but I like when things line up well :) Or the longer motors could be moved towards the front, but then would complicate things for the gear-train coupling them and going to the gearbox. Also, a big plus for the PF L motors is that they are about 30% faster than the PU L motors, hence when used with planetary hubs, they result in a more playable speed while still having plenty enough torque (for a model this size). Second, the steering. I like linkage based steering for a live axle due to its simplicity and realism. The shape of the PF servo is just great for this kind of steering, it is possible to make its output low, but the whole motor is not too low to take space from other stuff. Furthermore as the PF servo has a rear output, it can be used to route it to a working steering wheel. Last, but not least, it really seems to me that the PF servo is quite a bit stronger than the PU L motor for steering. (At least, based on some testing, my guess is that none of the control software make full use of the total power of the PU L motor, but it can make use of the power of the PF servo; I guess the difference might be in the complexity of the control algorithm, as the PU L motor is not designed for servo function only). Anyway, as I have tested both options, the PF servo was able to steer under a complete build with bodywork while stopped on rough terrain and the front axle being flexed out, while the PU motor was lacking here.. The axles are 13 wide, similar to my previous builds, though they are getting more and more slim :) The front axle has a complete 4-link setup with an additional Panhard rod that is placed quite low and results in minimal sideways sway upon flex. The steering is via a linkage directly from the servo. The springs are placed fairly close to the middle, so it has a good amount of flex, about 2 studs at the wheel. The rear axle is a 2-link setup with positive caster, and an additional Panhard rod, also placed very low to minimize sideways movement, which would be bad for the drivetrain as it only has a single CV joint. I think the resulting chassis is quite simple, clean and has good geometry. And it's not even over-crowded, so the build remains simple and gives room for other options such as using PU motors. So I built that version as well, sacrificing the perfect geometry in the rear, for the sake of comparison :) Obviously, the functional steering wheel is lost in this case, as the PU L motor does not have a dual output. Here's one more fun render of the inside The battery goes simply into the trunk, which is big enough for any kind. I use it with a Buwizz 2 for PF (high mode) and Buwizz 3 for PU (80% motor power). Bodywork As I said the model started out from the manual version, which being an alternate build had lots of simplifications. Here I wanted to address them, making it more true to the real one. One key area was the nose and the hood, I definitely wanted to improve the grill / lights and make that iconic raise in the middle of the hood. At the same time I wanted to use a different technique to the versions of @rm8 or Madoca, so I went with a tile based one, trying to mix it smoothly with the technic beams and panels. I think they complement each other nicely, and the result is smooth. Also, the windshield was raised to be properly placed and this way it also became foldable, and it got a more realistic dashboard as well. Another area of improvement is the doors. I wanted to make the doors visually separate and clean, which also resulted in a properly detachable and swappable construction similar to that of @rm8 / Madoca. Other areas of improvement are the rear fenders built using slopes and the curved rear corner, but that's just the same technique used by others before me. I also made the trunk open in a different direction than the manual one. And I changed the roll-bar to match the one on the image above. Custom tires This model was also ideal for testing my new RC tires I bought recently thanks to @HorcikDesigns. They are the same size (76mm) as the lego buggy tires, and they fit the rim nicely, and the material is also okay I think for the very cheap price. All-in-all the model is fun to play with, it has good amount of speed and torque. In fact, the only problem is that it is too light-weight and the drivetrain has enough power to spin all wheels under it quite easily even on rocky terrain. I was running it with locked rear differentials and open front ones. You can find many more images in my Bricksafe gallery. Building instructions are available on Rebrickable. Let me know how you like it! Cheers, Viktor

Oh, one more thing came into my mind about locked front diffs. Once I tried to build an axle with those lego portals and locked diffs, and I was shocked to see that it simply cannot steer in place. That is because of the large scrub radius, as you steer, one wheel is actually rolling forward, while the other is rolling backwards, and that counter rotation is twisting the drive axle between them if they are hard coupled, and the axle twist simply stopped the steering mechanism at a fairly low angle. Of course you could force the steering mechanism more, but I think that's not the right solution (rather improving the scrub radius). So curious how it will work out in your case!

Ah, you are right, upon better examination, it is indeed a bit shorter. I think that's just not true, it is in fact about 3.5 units distance, because the holes in a studded beam are further away from the bottom than from the top. You can also verify it by how studded beam layers are usually connected on top of each other: you put 2 plates between them when the studs of both are on top, and the height of 2 plates is less than 1 unit.

Great choice, indeed, those Lada Nivas were quite wide-spread over here, and I also have it on my backlog to be built at some point, though probably a smaller one. Those portals look really badass, curious how this will perform! Aren't you afraid of those 4 coupled XL twisting axles pretty easily? Or do you expect the massive portal reduction to take care of that issue?

Good to know, thanks for the feedback. Still, somehow I feel that a whole category of models does not make it to the front-page. Exactly my thoughts as well, I just did not want to go into it too much here. But as I see, Creator style has a much higher chance of being front-paged as opposed to pure technic. And I agree that your model is an example of something that would be worthy of front-paging. But let's get back on topic :) Yes, I agree with you on that! And I believe one way of making such rules in a non-complicated way is to have competitions in which the theme and the model size is not too varied, so entries are more comparable. For example, I think the small construction vehicle competition we had was a great example. All models were construction models, so no danger of fancy empty supercars taking the votes, and there was a size constraint, making entries roughly equal size. Now in this regard, a possible shrinking contest is already tricky, because the source materials are quite varied, and at best we can impose constraints on the size of the entries to make them comparable. Though that may work out in the end, because in the same size, a car model may not have an advantage over a construction vehicle (both will have their own strengths).

I think it's not so black-and-white about the rules, and it would not be enough just to disqualify entries that violate the rules. Imagine we have a shrinking contest without any constraints, and let's think about two possible entries. One contestant picks a 1:8 supercar, makes it 1:10 or 1:12 and keeps some of the few functions, maybe drops the gearbox; the result is still big and may look cool, but technically shallow. Another contestant takes a medium construction set maybe, makes it smaller but keeps all the functions with a lot of technical tricks and cool building techniques. Suppose that both entries would adhere to the rules, so none of them would be disqualified by the jury's pre-filtering, and then voting is passed to the crowd. Which one keeps the spirit of the contest better? Probably the second. Which one will get more votes? Probably the first. About pure jury voting, I could actually argue both ways. They might take the spirit of the contest better into account, but their viewpoints may be more limited and their own taste may also be reflected in the results. I actually see that as an existing problem with front-paging (which is somewhat related as it is the moderators' way of deciding which builds are cool enough and which ones are not that much). To me it seems to reflect the moderator's personal preference, and I see many more interesting and worthy builds here than the ones that make it to the front page.

That's weird, because as @Lipko says, I thought the problem would be perpendicular alignment of the two yellow bricks, but I just tried to connect them with a 3L beam (after bringing them closer longitudinally), and it seems to be a perfect fit.. On the other hand, 3-34 cannot be connected perpendicularly, so maybe @Jurss is right that it's the other way round. I guess longitudinally neither are misaligned, right?

Really nice target to build :) About the usage of a diff-lock vs a permanently locked diff, I have been wondering about that a lot too. On one hand I did build some models with locked front diff as well, but I had the impression that it does impede steering performance more than I would like. For example my Unimog alternate of the Zetros had that locked diff, and it felt like it was kind of trying to push itself straight instead of wanting to turn, if you get what I mean. Before that I did not think that an open diff would make such a difference, but afterwards I opt more for open front diffs and I don't observe that behavior. @Zerobricks's planetary construction seems quite a good one, I have checked it out and plan to use it in the future. However, I did not see an easy way to incorporate a new CV into it if the goal of that is to get the pivot point even closer to the wheel; one problem is the size of the CV joint's head being too big, but another difficulty will actually be building the support for the pivots due to space constraints. Maybe not impossible, I have seen such constructions in smaller scale with the old CV joint, but those were much less robust ones (only supported at the bottom and only using a plain axle not a wheel hub) that would not really fly for this large scale. If however the point would be not to move the pivot point closer to the wheel but only use a CV joint which is supposed to be stronger, then it might be possible but not sure if it's worth it. BTW, the CV joints have quite a good max steering angle, though not as extreme as the U-joint. Did anyone ever had a problem with a U-joint breaking in a portal construction? I have the impression that the reduction after the U-joint takes enough stress off of it.

Yes of course :) it is built on that chassis, so you already know the technical side :) Thanks for all the detailed insights about the anti-roll bar, it does make sense. Things become quite different when one steps out from the world of slow lego motors/cars (crawlers) to the world of fast RC ones I guess, different problems/challenges surface..