z3_2drive

I might just get the 42039 because of the potential for modification - we can make it into the beautiful endurance racer it deserves to be with flex axles and less jagged edges.

Some time has passed and I am currently working on the first version of this car (I'll revise it later to eliminate things such as chassis bending and excess weight). I took your advice the day you posted it and wow, it worked perfectly! Saved me a lot of time, and since then I completed the frame and started on the rear axle. I tried multiple setups which all had some underlying issues, but I think I came across a practical solution. I had to raise the ball joint on the rack a half stud higher for the perfect angle, and as a final result the bump steer is practically zero. I'm using efferman's 3D printed u-joints, hopefully they'll hold up. I'm showing the possibilities and challenges in building a 'performance' car with this build, as well as gaining more experience for myself. I really hope this build will work out in the end, wish me luck!

I noted from your videos that the steering arm must be closest to the arm that is the same length, but this was a quick solution that was very strong. How do you suggest moving it down (on the hub) in a manner that will keep the strength? I'll be fiddling around with it for a while until it's perfect so thanks for the input :)

After researching some more reliable suspensions for the front axle I started working on my own design, which is a mix of inspiration from various builders. My goal was to have caster, unequal length arms, and as little bump steer as possible while still being very strong. At the moment I am trying to find a good way to place a large gear and a servo to match the rack placement. The design is reinforced so there's little to no bend and it will stay together at high speed: I got the bump-steer down to a few millimeters at most, and I think that's as good as it'll get with the plan I have in mind.

This looks awesome! Good luck with it, I'm liking the use of dampers and I hope the rear suspension holds up at full speed. Right now I'm torn between making a trophy truck, muscle car, or crawler with my 4 motors...

The custom springs weren't necessary for this build-he was just testing as opposed to using normal soft Lego springs. Now, if he wanted some coils for a truck suspension where they could compress and stretch, what strong, practical Lego solution would you suggest? (Not a bunch of rubber bands). I also wouldn't like it if everyone simply printed quick solutions, but it would be nice to encourage Lego to make a model with similar new pieces where a purist solution simply doesn't exist.

I mix them...because it's fun Great buggy, Sariel, though I'd like to see a version with buggy motors

4 buggy motors are powerful with any batteries, but I use custom ones along with a 3rd party RC system. Much better than IR (range/current) and less bulky than using the official Lego RC system. I shoot for low weight and no gears, just the strong red U-joints for driveshafts, and try to build chassis' that don't bend. Other examples of excellent performance MOCs would be clarkdef's work or 2LegoOrNot2Lego's

This was on a wet surface, when it was dry it was pretty easy to keep it under control, but I owe that to the proportional+return to center steering. For me, you reach 'performance' level of building if the vehicle goes over 20km/h. Here's what I think is most important: Direct Drive - Even one pair of gears, especially perpendicular, will result in significant power losses. Having direct drive is the best option and requires a wide chassis, also necessary for high speeds. Differential - In the first video, I had 2 motors per rear wheel which acted as its own differential. The extra strain on the motors was minimal. Solid axle(no diff) will only work well if you don't use U-joints or CV joints as shown in the second video. This is because long driveshafts will twist or even break during high speed turns and jolts. Solid axle will also result in better control at high speeds but little oversteer, so no throwing the vehicle into the turn sideways Suspension - At speeds over 20km/h, regardless of terrain, suspension will be necessary. Without it, any bumps or simply the force of turning will put extra stress on the driveshafts and wheel hubs. Handling greatly benefits from suspension, and build according to terrain (stiff/low for roads and soft, high clearance for offroad). Also, if you can fit dampers into your suspension, it will absorb any bumps and go through turns beautifully. Suspension/Steering Geometry - I find the most important geometries you can incorporate in the strongest of systems are caster and ackerman. Anything to reduce bump-steer and stress on the shock absorbers will help. If you can incorporate camber, kingpin inclination etc without compromising strength, go for it! ​Gearboxes, unless you can shift them remotely and fluidly, as well as having no more than 2 speeds, are not worth it in vehicles capable of 20km/h+. 4WD...I don't know because I haven't tried it yet. If the system is mechanically linked, there will be significant power losses. If you have something like 2 motors in the rear and 2 in the front, just watch out for the suspension+drive, it has to steer smoothly and be able to survive stop-go motion. Personally, RWD is the easiest to build and most fun to drive, but if someone can build a FWD car with 4 buggy motors, that would be AWESOME, though understeer might be an issue

Love the design! Independent trailing arms are great but I don't know if they would work on a large scale with multiple buggy motors. At this scale it looks like it'll go great :) What do you plan for the body? Panels/flex axles/tubular/studded?

Sariel responded and I decided not to buy the high torque diff. Maybe sometime in the future. Here's what i did get: U-Joint with slide 12 tooth bevel with axle Curved liftarm 4x11 Heavy duty U-Joint 5m pushrod 90 degrees Axle Support Frame Driven Steering Hub small Clutch 24 Gear Rack 9L MacPherson steering hub Planet gearbox 4:1 Male CV joint 2m 8 piece set If you need feedback on any of these parts, they should arrive by the 22nd. Thanks for making these models!

3: 10 10: 6 6: 4 2: 3 9: 2 5: 1 All really great models, good luck!

I'm interested in buying some of your Shapeways creations but I have one question, do you think the high-torque diff is ready for testing? It looks very promising but it's still in Beta.

Amazing! The level of detail on such a fast vehicle is impressive, and I love the use of links in the rear. If I had the official RC unit I would definitely build it

I'll say it again, I love the way it turned out! All features are excellent, and the video editing... Good luck in college!

I build MOCs for the playability-trying to go as fast as possible, but If I build a small MOC for looks and functions, PF doesnt matter to me. I've made MOCs with and without PF, both being just as fun. I guess official sets now have PF more often because kids might pay more attention to toys that move without pushing them, and for big flagships it removes the tedious twisting of knobs. A good supercar like 8880 doesnt need PF, but if they can manage to make it fully motorized without taking out the original features, all the better!

Interesting, thanks for the info. I'll see if I can make my own diagram. Considering the stiff and high clearance setup in the front, maybe such forces wouldn't be a problem? I definitely want to keep the caster as is, though. The most important issue at the moment would be the rack.

Ah, I have that wrong? Well it's good to check. I'll make adjustments. Steering is far from final and it's what I have planned, yes. Bump steer is there because of the improvised rack I have just sitting there for now. The cylinder mods...it hurts to remove the inlets, but the dampening+spring action really helps when it runs! I'm still strengthening everything in the front as well as removing as much weight as possible because it struggles in acceleration. I predict the final weight to be 1.6 kilograms. The rear has no complex geometries for the sake of strength, but I could whip something up if it helps. I like critiques, keep 'em coming because this is in alpha stage EDIT: About the cylinders, You carefully pry open the black caps with thin pliers, pull out the cap/rod assembly, remove the top (there are 3) rubber washer and place the remaining two back in. Take the spring from a 9.5L extra-hard shock absorber and place it in the cylinder, followed by the rod assembly. Snip the inlets for room in your suspension/air flow. I got the idea from others who have done this modification, but I don't think anyone has explained how it's done. And about anti-dive, I'm still learning about the many angles involved, but I do recall this this.

I'm back with a lot of progress and changes! I now have a rolling chassis and the next step is steering. I made a rugged chassis and a double wishbone front suspension based on nicjasno's design, but with many changes and improvements in strength. I passed a large hurdle, but the steering is killing me at the moment Some differences from the idea I originally had in mind: Lose the Super Street Sensation wheels, replace with Chrome 42000 wheels. Slightly shorter chassis Almost fully studded frame, even in the front on the vehicle. Might allow more travel in the rear. Simple rollcage around electronics box (to come) Grease rear hubs Here are the photos: The proportions are closer to an RC car rather than a real vehicle, but hey, what am I building? This is why I might increase clearance at the rear, but that would mean risking the U-joints... This is a tough build when it comes to combining studded/studless dimensions. ^The beginnings of the rollcage which will strengthen the whole car. ^I had large plates, so I thought 'what the hell' and stuck em on. Also, looks may be deceiving, but the front and rear axle width is the same. It makes for a lot of weight, but as a result there is minimum chassis flex. ^Nice chrome wheels from ChromeBricks. The suspension has kingpin inclination, unequal wishbones, positive caster, anti-dive, and Ackerman steering. The rack is just temporary, because getting it perfect is a complete pain in the megablocks ^This is what I'm most proud of-at first I had no clue how I would implement the large cylinders between the wishbones, and then I thought 'Why do I have to?'. Luckily the width of the vehicle turned out to be perfect, accompanying the two cylinders in a very aesthetically pleasing manner. And to someone who loves suspension like I do, watching the compression is absolutely wonderful...I should make a gif If you have a spare 32L axle, stick it on your MOC to make it look like an old-fashioned RC car! My next update should be here once I figure out the damn steering. At the moment the perfect rack length adds up to 19.5 studs Wish me luck!

That's something you have to test! Personally I have not used gearboxes in high speed vehicles, but I think with simple 2-3 speeds without a clutch, you should let off the throttle and shift. Piterx's gearboxes run really smoothly, but I don't know if he has tested them with buggy motors. All I can say is go for it and try it!

Amazing bodywork at such a small scale, with performance to match!

I'm jealous of it's beauty As someone else said, I would highly recommend a stabilizer bar attached to the trailing arms via ball joint, it makes the model stronger and improves suspension motion. Like so, possibly two of them to avoid the motors twisting inwards in reverse. Again, this is definitely going on my favorites list!

I did try a prototype trial truck with this system at the same time Sariel was working on his own quad-motor truck...the extra power mine had proved to be too much for certain gear combinations, but the potential is crazy indeed. I think I'll give it another go after this project! To purists' horror, I did. I've had this differential laying around for a year since I found the idea on Brickshelf - a small hole is drilled in the center on each side so a Lego bar/light-saber piece can be pushed through, allowing for 2 rather than 1 bevel 'spider' gears. I figured this model might need it to avoid breaking any 12t gears. The current weak links are the u-joints. They're best Lego can offer, but in the event of a crash or constant stop & go motion they will be in danger. Thanks for helping each other identify the bionicle chest pieces The other rare pieces I used are the dark bluish gray Bionicle Torso sections.

Yup, in this: For some reason I find that a majority of these are cracked, in that particular spot, without having any stress on them. None of the similar axle & pin connectors have this issue. Perhaps this is a common defect where simply putting axles through them cracks the thin plastic over time?

Beautiful details and plenty of functions, what a great MOC!