Lixander

I might resurrect the bathtub dragster

I am not sure, but maybe because of the discharge rate. Usually, hobby-grade Li-Po˙s dont go under 10C. My 2S battery has about 30C, if I remember correctly, for example

Now, that you spoke about the voltage, I remembered.........the buggy motors won't handle a 2S LiPo because of the heat. Also, a charged 2S LiPo has 8.4V. I burned 3x buggy motors until I finally understood that a RC system would simply burn these motors. Probably, a RC compatible system thought for using with Lego electronics won't do that, because, most likely, the discharge rate is the problem (the ESC might give too much current to the motors).

Thanks! Well, I think you saw that the links don't actually link :))) The Flat baja II has some toe-in......not too much and at high speed, I think it is pretty non-existent. I had done (for other models) a version of the front frame that has the average wheel hubs, so enabling to adjust by half a stud the height of the link that the wheel has with the 6L link by using the new wheel-hubs, such as this ones: https://www.bricklink.com/v2/catalog/catalogitem.page?P=3468c01#T=C&C=11 Still have to test the sturdiness of this new frame.

I gathered here all my W.I.P.s that I plan to do. Also, from now on, I will put in this topic MOCs too instead of making different topics for each. ”Retro styled buggy” - 1x upgeared buggy motor that wont work probably (because of the upgearing and its 740 grams / 26.10 ounces), 1x servo, independent suspension on all wheels and detachable body (with huge wing, that most likely will make the model tip on the back). It takes some ”shapes” from the Tamiya Avante Mk.1. ”Test X” - a rear wheel-drive model which was meant for speed with the PF XL motors - nonsense, I know. That is why I pretty much renounced at it when I finished the first version. It has independent suspension on al wheels, 2x upgeared XL motors, 1x servo and has a modified Flat baja II front frame. ”APACHAIHAPACHAI 15 stud chassis mod” - this, but with 2x buggy motors. Also, great work @apachaihapachai ! ”Technic Tamiya Neo Fighter buggy” - based on a Tamiya RC buggy, but unlike the RC buggy, it has a 4x4 drive-line. Fitted 2x buggy motors and 1x servo, removable body-work, positive caster-angle and full independent suspension. Als, the weight is just under 900g (pretty decent, considering it is a 4x4 and that has a pretty body plus some useless pieces to simulate the electric motor of the real thing). One of the hardest parts that still have to be done is the battery hub frames, which don`t fit in the pretty small body. ”Technic Tamiya BBX BB-01 buggy” - encountering huge problems with the rear suspension arms on the Technic BBX, I kind of canceled it. But the idea was too great to let it just be unfinished. So I returned at the 2nd model file I made, which had 2 motors and an updated rear swing-arms, but visually it was a mess and I think that didn`t work as well. In any case, I am working on a 4th redesign; the renders are from the 3rd one. ”Flat baja-truck MAXX” - with chassis based on the looks and ideas of the HPI Jumpshot SC RC baja, it has 4x4 drive from 2x buggy motors and 1x servo. As main features, it has a (pretty big) positive caster-angle, independent suspension on all arms, consolidated steering rack, space for lights in the front and in the back, plenty of space for the battery hubs, detachable body and, the cherry on the cake, the distance between the suspension arms is 0 studs, enhancing the suspension behavior and travel. The front and rear are heavily modified frames from the ”Something 4x4”, a kind of a study created for testing the same idea for spacing the suspension arms while integrating a 4x4 driveline. P.S.: At its a little over 1 kg / 35.27 ounces, this will sure need another pair of shocks. I will see how I will put them. Also, I want to do a version with RC hobby-grade electronics. And here is a closer look at the rear frame with 0 studs between the suspension arms. This is a modified frame from the ”Something 4x4” from the bottom of the post. ”Ruslan baja-truck” - based on the Eagle V2 trophy-truck - thanks to @Daniel-99 for helping me with recreating some parts of his build. It has 2x buggy motors, 1x servo-motor, (big) positive caster-angle, easily removable sides, space for about 5x light systems (1/2x back and 3x front )and 4x 9.5L hard shocks for the 4-links suspension at the rear and independent at the front. I am planning to make a version with RC hobby-grade parts in it. Here are the original topics: ”Flat baja-truck II” - same features as the first one, but this time 100% of the design is mine and also it has less parts while it has a smoother look (for me). i am still working on the instructions, so until the final steps, I only have one render with it :/ I have another bunch of W.I.P.s, but most of them I don`t consider to finish at all. You can find all of them in the ”General archive” on my Bricksafe. Most notable ones are the (I wont add descriptions because you can find the Studio files on Bricksafe): ”Red Yeti chassis” ”Superstar” ”Something 4x4” ”Bathtub dragster”

Ok. Thanks for the answers!

That is a real breakthrough! One the first of these, if not the first actually, of such RC to Lego ”hubs” projects that will be easily available in Europe (I hope). Good luck! Also, I didnt understand exactly if it can use also a 2S Li-Po (max of 8.40V). If yes, then how is the connection of the RC Deck - battery made and is there any battery size limit (mAh or cm)?

I see. Thanks for the answer! Also, if I cant fit the gear reductor on bigger motors........can I take the original setup to off-roading, maybe even some crawling? (I mean if the motor and ESC that are in the original setup will withstand the conditions of such usage, especially the ESC)

Nice and practical product. i am interested at least in the differentials, but I want to use other brushless motors with them in off-road builds. So the gear reduction frame, differentials and the wheel hubs (probably the ones for 1/8 because I dont want to move to full RC wheels yet) work with a brushless Surpass Hobby F550 3800KV with a 90A ESC (on a 2S Li-Po battery)? https://www.aliexpress.com/item/1005005016153941.html?spm=a2g0o.cart.0.0.53bc38daKb1S9H&mp=1

Let's hope it will be that way. And also I hope it won't have steering problems :/

This has nothing with the other Flat baja`s in common, just the name because it is pretty flat. New W.I.P.. in the stash..........here is the Flat baja-truck MAXX. The chassis is based on the looks and ideas of the HPI Jumpshot SC RC baja. It has 4x4 drive from using 2x buggy motors and 1x servo for steering. As main features, it boasts a (pretty big) positive caster-angle, independent suspension on all arms, consolidated steering rack, space for lights in the front and in the back, plenty of space for the battery hubs, detachable body and, the cherry on the cake, the distance between the suspension arms is 0 studs, enhancing the suspension behavior and travel. I will come back with more specs in a new topic with all my W.I.P.s posted in there.

Well, making new projects is pretty fun but not when you realize you have at least 4 to finish and you cant even continue the majority of them because of the pieces and mainly time. In other words, I added another ”W.I.P.” to the stash - a retro styled buggy that uses a modified front frame of the Flat baja II with bigger wheel hubs.. As motors, it uses 1x upgeared buggy motor that will probably wont work because of the upgearing and its 740 grams ( 26.10 ounces ) and also 1x PF servo-motor. It also has independent suspension and wishbones on all arms and detachable body with a huge wing that will probably make the model tip at the back. As inspiration, I had the Tamiya Avante RC buggy, mainly the old Mk. 1 of the model.

Interesting model duo :) I really like the small model more, but the base is good too. Both are packed with functions and the link between the 2 models is a very clever solution. Keep up the good work!

Great idea! Looks really good and seems really promising on the functional part too. Looking forward to see it finished.

Thanks for the appreciation. Well, I want to use metal joints, but I usually connect the wheel-hubs directly. In other words, they will be useful but everytime I replenish my parts my mind skipps the metal joints. The battery hubs should go in the back or in the middle of the chassis, I still didn`t figured where I should put them.

When I started to build the BBX, I encountered huge problems with the rear suspension arms. So I kind of canceled it. But the idea was too great to let it just be an unfinished concept. So today I returned at the 2nd model file I made, which had 2 motors and an updated rear swing-arms, but visually it was a mess and I think that didn`t work as well. In any case, as a 3rd attempt I integrated the 2x buggy motors in the chassis and tried to create robust wheel-hubs frames. Also, I put 6.5L shock absorbers at the back too for a more affordable model, but I had to figure a way to ”fill” the gap made by the smaller shocks. For this, I made some fake shock absorbers. I really hope that this rear arms will also work properly and also look better in reality. Also, here is the link for the older renders and screenshots: https://bricksafe.com/pages/Lixander_A./bb-01-buggy-wip/archive

Approaching the final version. I still have to test it properly outside, but the main problems seem to be solved. You can find the new digital file on Rebrickable

Also, here are the .dat files for a 540 size RC motor and an RC axle adaptor. They need to be edited in the Studio Designer, to put the connections. https://bricksafe.com/pages/Lixander_A./miscellaneous/rc-adaptors I made the conversion of the 3D files with the help of this program https://github.com/Nexusnui/stl-to-dat-improved He also made a tutorial. The original 3D files: https://cults3d.com/en/3d-model/tool/540-motor-mount-for-lego-technic https://cults3d.com/en/3d-model/gadget/540-motor-to-lego-axle-adapter

I see. Good that you know the problem before it even appeared.

Try to avoid long axles made from one piece, especially with such a setup (motor power). But the for the win, get he metal axles........even if they are not so cheap, for such a model they are a must, as you saw :)).

I see. I would suggest to start a simple body-work, but taking in account that you made a pretty complicated chassis, I dont know...just build and test :))) Good luck anyway! Yes it is. The RC shock absorbers have a larger suspension travel and can be adjusted to the desired stiffness and height, from what I know. Also, the large Lego shock absorbers are expensive, especially the 9.5L hard and extra-hard ones.

I know the pain when you made a good chassis and you still have to do the body-work. Some months ago, I started to look for inspiration for my body-works, especially for the techniques not the shape or the pieces themselves. So, I put here some videos and a Rebrickable baja-truck that might help you with the body-work. https://rebrickable.com/mocs/MOC-4874/RM8 LEGO Garage - BrickGarage/baja-trophy-truck-double-trouble/#details

Even with these wheels, it looks excellent! Great job!

I improved a few things, especially visually. For example, I made the motor frame narrower. I still need to recreate the last version in real life, because the real version differs from the last, which is often digital; even if they are the same theoretically, the last (digital) version has small improvements.

I thought how to find a more convincing purpose to this build........so I turned the baja-truck into a ”baja-responder” - I think it sounds better ”baja-responder” than ”baja-first-responder”. Even if I just added a ”storage space” at the back, which adds to the weight too, this gives more purpose of the build in the Arctic theme (my opinion). I tinkered at the chassis too; as late as tomorrow I will post the real progress.