Didumos69

This afternoon my kids and I had an outdoor RC buggy session . Kids with their toy RC buggy's and me with my Technic buggy. Here's a compilation of the video's we shot of my model. We shot video's of theirs too of course . My son did most of the filming (I had to beg him ) and even presented himself as 'live commentator' (Dutch only, sorry). The entire session passed without any problems or displacements in the build . Also the U-joints survived, thanks for the hint @nerdsforprez!

Can't you flip the whole thing upside-down? Do you have space to lower the lever two studs?

Thanks! You mean your Nomad? To put so much power to the front wheels only works if there is minimal slack in the front axles. Here are a few things I changed: 1.) The steering rods still had some play in them, because of the use of half pins and 2L axles that don't sit tight. So I used studded parts to connect the parts instead: 2.) The turn-table based wheel hubs work best (have the least slack) when the turn-table is integrated with pins rather than axles on each side of the turn-table. In the rear hubs I have that already, but for the font hubs I had to use axles on the chassis side of the turn-table. This gave some play between the turn-table and the chassis side of the hub. But with a belt wheel tire filling the space between the turn-table teeth and the chassis side of the hub, I could remove slack completely. 3.) The wheels are attached to the hubs with two axles sticking out of the hubs. Sofar I used 4L axles with end-stop and put half bushes and 3L levers (yellow) on them to prevent the wheels from sliding off. This worked quite well, but after a rough ride, I allways had to tighten these parts again. To solve this I used a trick with rubber connectors attached to the axles sticking out of the hubs, 5L axles with end-stop in.this case. The rubber connectors are squeezed to secure them to the axles. I have shared this trick before and was criticized that I could obtain the same with half bushes, but reality proves different: I made several rough rides with this trick installed and nothing needed to be tightened or readjusted. It simply works. 4.) Finally, I added some constructs to better square and reinforce the A-arms in the front axles. When the lower A-arms hit something, they got easily disconnected. And because the legs of each A-arm are wide apart, they didn't square well and introduced some sloppyness. So I added some constructs with crankshaft pieces that connect the legs of the A-arms. This squares the A-arms better and make them strong enough to absorb frontal impact without disconnecting. Now it's time to take it outside again

Thanks! A lot has to do with the BuWizzes that I'm using. And the fact that each motor drives a wheel directly. The hard part was to get the front axles strong enough to handle the power without getting a lot of toe-in. I pulled some tricks to reduce slack here and there, but nothing illegal and only LEGO pieces. I will show pictures tomorrow. Yes you should!

Thanks! That's a good idea. The only thing is that this looses its blocking function for one steering rod in turns. Another thing I was affraid of is that the steering rods would trouble the steering rods too much in turns, as the hub ends of the steering rods move quite a lot forward in turns, but eventually this didn't turn out to be a problem at all. I tried something similar with a second pin with pinhole next to the one suggested by Lipko, but that did obstruct the steering rods in turns. So this is what I did: Two pins with pinhole connected with a 3L pin (there is only one stud space between them) and two tow balls next to them. And now it can climb a slope: Thanks guys! Problem solved

Here is a render showing the area where the steering rods connect to the gearrack and a render of the complete gearrack assembly. The problem is that the steering rods pull the pins with tow ball out of the gearrack assembly. There is some space in front of the gearrack assembly and the steering rods, but practically only half a stud, because of the knobs of the blue half pins holding the motor assembly. So I'm looking for a way to block the suspension arms, which takes only half a stud of space. Preferably, the blocking structure should be connected to the gearrack assembly, so it moves along with the gearrack and steering rods.

Great work sofar! Can you show a picture of the model without the wheels? Would love to see the details of the breaks. As for the sketches, I say post them. It is relevant, so what would be the problem? Good luck with the collaboration!

Thanks! This is very helpful. It means I also need some kind of blocking structure. The steering rods shown below - with Ackermann geometry - are placed at the back side of the front axles and are connected to the gearrack with pins with tow balls pointing backwards. When the model takes a climb, the traction of the front wheels pulls the steering rods outward, causing the pins with tow balls to disconnect. I can't make renders right now. I'll post some renders tomorrow to explain better. Yes, it slides with Claas tires. Even on the carpet . The sharp steering angle is paying off. Thanks @Zerobricks! I agree using hubs to carry the weight is better, but I think you missed the fact that I'm using turntable based wheel hubs (see video in OP, I now use 4l axles with end-stop instead of pins to connect the wheel to the hub). I don't like the slack in the standard wheel hubs and I wanted a decent steering angle. With the U-joints I have a 30 degree steering angle and with the turntables I have less slack. Currently I have wrapped white silicon bands around the axle holes of the U-joints (4 times), as was suggested by @nerdsforprez, and I haven't had any problems since.

Hi @agrof, I remember you are using this 2L bar with tow ball in the steering setup of this model. Can you - or whoever knows the answers - tell me how tight the bar end sits 1) in an axle hole?, 2) in the small hole of a 2L pin with friction ridges while that pin is connecting two pin holes?, 3) in the pin side of a half pin which is inserted in a pin hole? and 4) in the knob side of a half pin which is inserted in a pin hole? Would one of these options sit more tight then a pin with tow ball in a pin hole? I'm looking for a way to improve my steering rods in my 4WD buggy. The pin with tow ball I'm using disconnects when the front wheels generate too much traction. Thanks!

Looks great and I really like the idea of having a platform that can serve as base for all kinds of SUV-like vehicles. I only doubt whether anyone will actually use it to build their own bodywork, but building a chassis-only model can be fun too.

Nice, but not available in the Crane profile, the only profile with 2 BuWizzes.

Thanks! I made sure it can be build without any illegal steps or constructions, so eventually I will be sharing photo instructions. @kbalage, I took the tripod and filmed some indoor driving excercises . This kind of treatment does not cause any displacement of parts. Only a serious frontal crash causes displacements.

Thanks! Yes, I have a tripod, but I'm waiting for good weather, because riding with ludicrous mode in our living room does not seem like a good idea .

Thanks @DugaldIC! And thanks for pushing me in the RC direction. It's really fun and building something that doesn't fall apart during a rough is an even bigger challenge than with a manual model. They do not really look like dirt grabber tires, which is why I didn't consider using them before, but eventually I have to conclude they do add to performance and overall look. As for hardening the suspension, I tuned the suspension to an extra weight of 500gr. With the extra weight, it sits approximately one stud deeper in its suspension which makes the wheels really glue to the ground on uneven surface. Thanks! The CLAAS tire size is 107x44. They are the biggest LEGO tires that exist.

I installed the CLAAS tires and softened the rear suspension a little. I love these tires! Only downside: While riding circles in ludicrous mode one of the front wheel tires ran off its rim!. In the video below it rides in normal mode (not ludicrous and not fast), because I can't drive and film simultaneously.

Let me know how this works out.

If I'm correct you only need to change the gears at the front side of the gearbox: Make sure the 24t gear and the 20t gear are on the right side of the gearbox, and their counterparts (8t gear and 12t gear respectively) on the left side. The 16t gears underneath the clutch gears and the 8t gears in the back are okay Yes. EDIT: That is, the gearbox ratios itself, so not taking into account the crankshaft-input ratio and output-differential ratio.

Few things: I assume we are looking at the left side of the gearbox, the side that should have 1st gear (rear clutch engaged) and 2nd gear (front clutch engaged). I don't understand the 16t gear on the right and ignore it. This is a gear setup that should work. Green is input (engine side) and yellow is output (rear axles side). It will give you ratios: 1:5 in 1st gear, 1:3 in 2nd gear, 3:5 in 3rd gear and 1:1 in 4th gear. Alternatively you can use the axle with the 20t gear as input, the one next to the input axle in the render. That will give you ratios: 1:3 in 1st gear, 5:9 in 2nd gear, 1:1 in 3rd gear and 5:3 in 4th gear. Or you can have the output axle engage with the axle to its other side. That would give you ratios: 3:5 in 1st gear, 1:1 in 2nd gear, 9:5 in 3rd gear and 3:1 in 4th gear. You can of course move each gear pair (black or dbg) from the front side to the back side of the gearbox or vice versa, as long as they are attached to the same axle and each pair remains engaged.

I don't think this is cool at all. And I would appreciate if we could stay on topic.

Thanks @nerdsforprez! I will certainly be using that. Will probably be using silicon bands to keep it pure LEGO (besides the BuWizzes of course). EDIT: I ordered 5 CLAAS tires, which were not that expensive btw. Less than 4 euros.a piece.

Here's what I will do. I'll accept the injuries that come with RC. I just have to get used to that. I will try to protect some parts, especially the front wishbones. They are quite vulnerable being all up front. Yesterday a hard frontal crash ruined the wishbones and the wheel hubs. I will also accept the extra weight of the CLAAS tires, even though they do not completely match the class one look. They look awesome and give me more ground clearance and more speed. On uneasy surfaces, gravel or cobblestones, it currently has so much power that speed is not affected. So I reckon I could trade some power for speed. I might. I have 8 yellow small shocks laying around so it would only involve the necessary refactoring. I will do that after finishing the default design..

Wow! You did it again! A highly detailed AND highly functional model! And a manual model this time! I also like the inclined plane made by the bottom line of the side windows. That's very hard to do. There are a lot of good looking models out there, but for me this one sticks out because of its perfect marriage between looks and function. Excellent work! EDIT: You should add a custom thumbnail to your video (one of your pictures), the one generated by youtube is blurry.

I think it looks awesome . It would also add speed and ground clearance .

Thanks! Didn't know that, thanks for the suggestion. I will certainly put them on in LDD to see how they look. It is indeed fun to drive, but after taking stock of the damage I'm afraid I will opt for a more easy surface next time. Probably a gravel road, a cobblestone road or grass. I don't really mind having broken one U-joint, because I blame the ludicrous mode, which I wouldn't mind avoiding anyway. Ludicrous mode is like playing with fire imo. No, I'm more concerned about the scratches all over the bottom side:

Thanks! I don't know about the exact voltage in ludicrous mode, I thought 9V. It's weight is currently 1250gr including BuWizzes. I hope to keep it under 1750gr eventually. I try to keep it as light as possible, but I also believe many LEGO Technic buggies are too light for their suspension. The vehicle should hang in it's suspension to make it float. I've seen too many videos with models that actually bounce and shake more because of their suspension.