Appie

This MOC from JoKo instantly comes to mind when trying to make "Mario Karts"

Thanks Mahjqa and thanks for introducing me to the truck in the game that fueled the desire to make it in Lego

Thanks everybody! Yes, in the game the springs are behind the wishbones though. I had a setup of 2 springs on each wheel (first axle had hard-hard, middle had soft-hard), but that turned out to be overkill for the first 2 axles. Anyway, they could be mounted at the rear of the wishbones, but for the front axle I opted to place them in front of the wishbones so I could make the section around the steeringmechanism even sturdier. For the middle axle its partially because I made this adjustment once the model was pretty much finished and I had no desire to remove the rear of the chassis to remove the hub so I can move the 5L with with stop that has the spring attached the other way around The truck from the game is based on a Russian truck, the ZIL 4972. They made all sorts of these kind of trucks as can be seen in the video below (I think the ZIL 4972 is clear in the video at 1:10), some types had live axles I think and others got independant suspension. I considered quite a few times to make it live axles instead, to get the diff locks in for example, but in trying to stay true to the game truck, I felt it had to be independant suspension.

Based on a truck called the Albatross from the game Mudrunner Expeditions, I made this MOC: The truck in the game: It has the following functions: - 6WD powered by 2 PU XL-motors - Front and rear axle steering powered by a PU L-motor. - V8 fake engine. - Winch at the front and rear of the truck, powered by a L-motor and through a little gearbox you can select if you want to power the rear or the front one. - Independant suspension. A video of the model: A few more photo's: The "fuelcap" (the black ball) on top of the "fueltank" turns on the hub. The bionicle tooth you see below the bed at the rear is the gearbox switch for the winch. Technic fig compatible I am really pleased with how the suspension works. The first 2 axle have 1 hard spring per wheel, the rear axle has 2 hard springs per wheel, because of the hub in front of that axle and the overhang at the rear that houses the motor for the winch (and with this setup it can actually carry a load of cargo too ) To remove the batteries I have to remove 2 liftarms and a part of the drive axle, which I build so it can be easily removed by me. A few things I didn't manage to do, but wanted to are stuff like a 2-speed gearbox and diff locks. but I simply could not make them fit while keeping the functions that did make it into the model. I wanted to keep the central column of the chassis slim (like the truck in the game) and keep the bed clean for actual cargo, so that put a limit on the space I had available. Diff locks either meant a higher drivetrain (at the cost of the V8 and bed probably) or a wider model (I can't think of a diff lock mechanism that takes less than 7 studs in width). A greater desire to use these parts for the independant suspension combined with the planetary hubs meant it would get 2 studs wider, which felt too wide for this tiresize. I also feel like the front of the cabine should be 1 stud longer forward at the expense of the hood, but I loved this Technic panel on the hood too much to let that go (and the tiles on the sides would be very hard to attach if I put it 1 stud forward, so hard for me that in the current build I stole a stud from the door instead to secure the A-pillars ). Sorry for no video yet, I might make one in a few weeks. The problem is at the moment that I have to use the one thing that could make a video to control the model through the Brickcontroller app Thanks for watching and reading!

Very nice progress and that mechanism for the trunk is very satisfying to watch. It opening fully with a minor push at the start and it closing on its own after a minimal push is great.

Exactly this. Great work JoKo! Me too!

In a car I build a few years ago with a weight of about 5kg, I needed 3 hard 6.5L springs for each wheel to keep the suspension functional (and to this day it still is). Instead of the old 11.5L springs from motorbikes you linked, you could consider these springs Lego uses in current 1:8 car sets (Ferrari and Mclaren) and 1:5 motorbikes (BMW and Yamaha). It's outside spring actually does nothing, the heavy duty spring is internal and is stronger than about 3 of these 9.5L very hard springs based on a quick test of a buddy. So this should give you quite some wiggle room compared to my setup of 12 6.5L hard springs to keep 5kg up. Great progress on your build btw, will be following this with great interest

What an awesome model. From the technical functions to the looks, great job!

The fix in my previous post is wrong. I thought I fixed it, but turns out I didn't. I used the same hub to install the Pybricks firmware on it to try and play around with that a bit and then restore the normal Lego firmware. That all went fine, but now the problem of the steering going left on startup of the program returned, while the ports were in the "I fixed it" position. So I fixed nothing Steering motor on port A or B, it still messes up. One thing I did find out though. When everything is ready to go and I press "play" in the brickcontroller app and the steering turns left as expected, but when I press the back button of my phone and then press "play" again in the brickcontroller app, the steering goes from the left to the center and everything works fine. I am going to assume this was always an option and I jumped to gun by going automatically to recalibrate the steering instead of trying this. It's weird bug from somewhere, but only having to press "play" twice to make it work normally is alot better than thinking I needed to recalibrate everytime I turned on the hub.

Great video Mahjqa. It was great fun. Thanks for hosting the event and making the video!

Mahjqa made a video and posted it in the other topic in which this car has some screentime Thanks Mahjqa for the awesome video! Looking forward to seeing that 9 wide car in action @gyenesvi I have/had plans to upgrade my previous car (the little yellow/blue Dakar truck) with 9 wide axles.

I looked it up actually, because I always mix them up , but nope, it's negative camber. The front axle has this problem because the parts that hold the CV-joints are only linked to one other part at the top. This causes that part to bend outwards, which gives the wheels negative camber. It's minor, but it's there even with the 7L liftarm there to help prevent it. It's shows itself best on a dusty floor: the rear tyres have dust only in the middle of the tyre, while the fronts have it slightly off center of the middle of the tyres. To (nearly) completely remove it, I'd ideally have to connect the bottom of those parts that hold the CV-joints to each other, but this ruins the ground clearance. Mahjqa and Jovel (see the truck trial topic from Mahjqa I mentioned in the OP) have countered this with not only securing the gearrack with another liftarm below it (like I did with the thin 7L liftarm), but where I used a 3L axle to secure it to the part above the CV-joints, they used a 5L+ axle to add another liftarm above it to counter this effect. That works better, but it's alot of lost space for a small gain, so I opted not to use that.

Not much. Play in the system isn't much different than a few gears in that same spot. The wheels can't wiggle much left and right when steering is in neutral. Also, while the steering motor axle can move 90 degrees, the axle of the steering can't, it does about 75-80 degrees, because the front axle has a 7L thin liftarm below the steering rack (see belly photo) that acts as a steering stop too (touches the liftarm in front the 20T bevelgear there). The 7L thin liftarm is there mostly to prevent negative camber, the steering stop was a sort of bonus. So at full steering lock there's practically no slack. I want to see if I can change the setup to prevent negative camber while unlocking those last degrees of steering angle, but so far can't think of something that I can mount in that area that doesn't compromise ground clearance and still has a positive effect to counter negative camber. I'd like parts for small RC builds too, but I am already quite happy with the new CV-joints we got for it. Though a dedicated small hub part for it wouldn't hurt

Thanks guys! I had to breach a gap of 4 studs for the steering. Normally I'd use 24T gears, but those wouldn't fit, so I used this instead. The bottom goes straight to a steering rack on the front axle through an old style cv-joint. The reason there's a 6L liftarm on there between the motor axle and steering axle is because shorter liftarms could get stuck on edges of the City hub (this is also the reason for the quarter round tiles on top of the hub). Personally quite proud where I managed to hide the cables At the front I had space left between the 2 liftarms besides the motor: So I could fold it up between the motor and the 6.5L spring and liftarms. To prevent it from going into the steering section I closed that off with a thin liftarm (you can see it on the steering photo). For the rear I didn't have the luxury of that space, because I needed that space to brace the drivetrain gears. So I used a little bit of the bed: It's basically swirled up below these 2x 3L black axle pins. The hole in front of the 2 pins is where the hub is secured and a little more outwards where the mounting is for the rollbar The final bit has to go over the 3L axle pins due to the mounting points for body work, but I have the space of 1 plate/thin liftarm between the rear of the cabin and the side of the cabin where that wire goes. This is how it sits before the left side bodywork goes on:

I had this as well yesterday, but with PU hub I assume you mean the small one used in City sets? Perhaps it's related to something else I found yesterday. Whenever I wanted to start up my model (car with drive and steer), the steering would always go to the left at start up of the MOC profile in brickcontroller 2 and stay there. Every single time. I could fix it by pressing reset or recalibrating the servo in the app, but that would only fix the issue until the next time I turned on the model. At times it would get stuck (similar to what you were having) in one direction during play as well, which you could stop by flipping the joystick the other way, but until then you could hear the motor beeping that it wanted to keep going. I did some testing and I think I found the cause of the issue for at least the steering going left and staying there on start up. I had the steering motor mounted on port B of the City hub, which was fine sometimes when that was the only thing I plugged in, but it would pretty much always fail once a motor was hooked to port A as well. I tested this with 2 L-motors (the one in the model that had the problem and another unused one). I also tried 3 City hubs with these 2 motors, all showed the same pattern. I tried to do one of those hubs with old hub firmware, but while brickcontroller found the hub I could not control any outputs, so I updated that hub as well (all ran latest Lego hub firmware). Once I put the steering motor on port A and the drive on port B I had no problem. I guess either in the hub firmware or in the brickcontroller app something messes with port B signal. Now I wonder Gyenesvi, if the motor that caused your problem was hooked up to port B as well? If this bug in either the Lego hub firmware or brickcontroller app was already mentioned, I apologise. I hope it's something @imurvai can shed some light on. edit: doesn't look like I fixed it, see here.

Some might remember Mahjqa's topic where I made a chassis based on AutoBacon's MOC. This is the finished model: It's driven by a PoweredUp City hub and 2 L-motors. The truck weighs 752gr (including batteries). It's downgeared with 2x 12:20 gear combinations (1 at the motor and 1 at each axle) which makes it pretty good at overcoming obstacles. In case you wonder, the choice for knobgears was because I couldn't figure out something else that wouldn't skip in the available space. The half pins which are inserted into plates below the hub help with the structural integrity of the chassis. In the stud.io file I made for the chassis I had a 9L link across the width of the model in that area, but I later found out the front wheels might touch that construction during steering. I'll adjust this in the stud.io file. Tried my best to give the model an interior. Below the black tile of the "seat" is the hub and liftarms that give the chassis its rigidity, so I didn't have much room to play with. To turn on the model I need to use an axle to press the button below the "passenger's seat". I would have loved to have a video for you, but I only have 1 phone which I use to control the model through the Brickcontroller app. @mahjqa has made some video's of an event last weekend where I used this little car (with slightly bigger front fenders), I hope he releases a video soon Thanks for reading and I hope you enjoyed it.

My guess is because they are on a corner of the vehicle. Especially the front corners would be very likely to get bumped into a wall with kids (and adults ) driving it. I think the 1L wide toilet paper part is more likely to break at the corner than the 2L liftarm.

I made a stud.io file for the chassis, available here: https://www.dropbox.com/scl/fi/00ccqyyzdxi3hlswbzzjj/CompactCrawler.io?rlkey=rdpojjy2399r0bb1e6mgnzrb6&dl=0 It should be complete, but if you find any issues let me know. Also something of note perhaps if you build this: when you press the front suspension so both springs have to compress, the movement is a little bit limited by the 12T gear from the steering that bumps into the L-motor. I have no issues with this, because for crawling action it's usually one side being compressed and not both. For one side being compressed it has no issues.

@AutoBacon Thank you very much. I like how sturdy it is yet compact as well. I made it a little sturdier even since those pictures. Secured the connector at the bottom better near the knobgear on the driveshaft and used the battery box to prevent the base from tearing apart down there (mostly a security measure for when it tumbles, not something the drivetrain tears apart). I don't have a studio file yet, but I would like to make one. And yeah, I am looking forward to the next round, quite confident with what this chassis can do. At the end of May we go again. As for the steering, it was a little annoying, because the space between the axle of the motor and steering axle is 4 studs. I didn't want to use 24T gears to bridge that gap, since those would touch the liftarms to the sides of the motor. So I came up with this: Not in the picture, but on the right side of this I placed a liftarm with half pins that act as stops above and below the top 2L liftarm from the motor, so the steering motor can't turn too far. Also, it's 5L liftarm between the 2 axles on purpose there, 4L had the tendency to get stuck on the lower rim of the battery box, this solution prevents that from happening. I have yet to have it happen at the top of the battery box, but then a 6L liftarm is an option. It being locked in by the battery box is something I like though. Making sure the whole mechanism won't run off axles. (also the tan axle from the motor is an axle pin. I used it as placeholder until I was done testing stuff) Also, yesterday I made an attempt to lower the springs one stud: In the end I didn't use it and reverted back to the original design. Obvious flaw is the springs not being able to move sideways naturally, but the suspension in general didn't work as smoothly as the previous design. And the axle as a whole felt a little less sturdy. Geometry with the new spring location felt off a little too. The spot I lowered them to is pretty much my only option and couldn't go wider there either or I'd touch the tractor tyres.

Thanks. Interesting method for the spring. Thanks for the suggestion. Personally I consider even just the spring legal, since that is also a Lego part (and I have made a MOC with it in the past with the spring running on an axle), but I want a normal alternative for which you don't have to disassemble parts that are normally not disassembled (for that old MOC my alternative was a suspension with rubber bands). It's just a weird personal rule I have when I make MOCs

Finished the chassis for that new axle I posted earlier, inspired by AutoBacon's work I wanted to keep the heavy parts of the model as low as I could, so I placed the battery box right above the drive shaft. As you can see I didn't manage to lower the front springs 1-2 studs. I might change the LBG part of the springs to yellow or something so I can hide it in the hood . The rear axle is pretty much a copy of AutoBacon's, except for the springs and I used another grey link on top (for symmetry with the front axle as the front has 2 as well to make sure an old style cv-joint for the steering won't pop out). Wheelbase is 18 studs. 3 studs shorter than my previous truck and if I am not mistaken 1 stud shorter than AutoBacon's pick-up truck (I was aiming for the same, but I misscalculated ). Gear reduction is 2.8:1. It climbs better than my previous truck. That truck had 4:1 reduction, but I think with the slippery obstacles and that with these tractor tyres, having some speed to get a running start on an obstacles helps. The balance is also far better with the lower center of gravity. Now to figure out what kind of body I want on it (will be something pick-up or Jeep-ish probably).

For this competition it was not, had to be 100% Lego. And actually, even if it wasn't a rule, I'd make it a rule for my own model. I like to keep my building solutions within the Lego options.

Yup, another builder noticed that while we were making the models (sadly he couldn't join for the video). Mahj's little truck from the video uses the same new CV-joints with that part and uses a 2x2 round tile with a hole in it to fix this rim touching problem (the extra surface also helps against the wobble you mention). As you can see in my picture I am using a 1/2 technic bush. For now at least, I'll probably change it to Mahj's solution. Ideally you want something of a 1/4 bush as a spacer to not rub the rim, but a tile is the closest we are going to get to that I think. As for the Mustang rims, I personally didn't notice a difference between them and the normal standard rim in terms of touching the above pictured part. Another solution would be this rim: https://www.bricklink.com/v2/catalog/catalogitem.page?P=6595#T=C With this rim the part does not touch the rim, but it's not a current rim, it was used in sets until 2006, but there is a 56mm tyre that would fit this (the red fire truck in the video uses these rims+tyres). Thanks, I love working on these small scales, like you said, you need to pick your parts carefully. For example, originally I removed that thin 7L liftarm at the bottom of the steering rack from your great design, then I noticed it functioned as a steering stop and prevented a little bit of the wheels bending outwards. So I put it back in I love such effective part usage.

Great to have you back. Gorgeous MOC!

What a great little buggy. I can see why you like that chassis, looks very clean and solid