4WD RC Buggy




Greyhound - 4WD RC Buggy with BuWizz 2

First of all, a big thank you to everybody who supported me in the corresponding WIP-topic on Eurobricks!

2019/03/15 - I improved the way the rims are connected to the turn-tables and updated the instructions accordingly. I made MOD-instructions in case you would want to upgrade your existing build with these changes: https://photos.app.goo.gl/nAw92pxpnCykSkSj8

2018/12/08 - The first and probably only links that can disconnect while driving are the pins with towball that connect the gearrack assembly to the steering links. Based upon reports from people that have built this model, it's highly advisable to use set-screws to secure these pins. Drive the screws all the way in. They should surpass the outer ridges of the pin:

2018/11/19 - I corrected the image showing the WD40 spray. It now shows PTFE spray, as mentioned in the text.
2018/11/18 - I made a small correction to the order of images.

Apart from pursuing performance, this model explores what's possible when it comes to robustness and durability. This has much to do with the fact that this is a 4WD model with 2 BuWizzes. A lot of power is sent to both the front and the rear wheels. That puts high demands on the strength of all kind of things; the steering, the suspension, the chassis, the bodywork. I had to think outside the beaten track on all these aspects, while holding on to requirements such as Ackermann geometry, small turning radius, extensive suspension travel and minimal slack in moving parts. But adding strength and coherence comes at the price of using more parts, which adds weight, which requires even more strength, etc. With this model I have tried to find a balance between performance, robustness and weight. A balance that fits the power of 2 BuWizzes and 4L motors on the one hand and a 4WD model built from LEGO on the other hand.

-Pages 163, 169, 303, 304, 349 and 350 show the results of obsolete steps. They are made transparent and have a red cross at the bottom-right corner. They only serve to inform you about some additions that should be ignored in further steps. The replacement steps are at the end of the instructions, starting from page 703.
-If you want the BuWizzes to be removable more easily, remove the red pins holding them, after page 532.
-To avoid wear and improve performance, it is advisable to lubricate the springs and the turn-tables. Use PTFE spray from WD40 (so NOT the normal WD40 spray). The impact modifier in ABS dissolves in the silicon carrier in silicon spray. WD40 PTFE spray does not have this issue.
-Try to keep your turn-tables clean.
-2 BuWizzes are not included in the inventory.

-Turn-table-based wheel-hubs with minimal slack
-4WD by means of 4 L-motors powered by two BuWizz 2 units
-Fully independent suspension
-Steering with Servo-motor
-30 degree steering angle with Ackermann geometry
-Caster angle
-Fake V8-engine driven by M-motor
-Can handle a rough ride
-Liftable by roof, nose and tail
-Everything in-system

Notes on parts
- 99773 (Technic Beam Triangle Thin [Type II]) used inside the front suspension module should not be confused with 2905 (Technic Beam Triangle Thin [Type I]).
- 95292c01 (Technic Shock Absorber 9.5L with Extra Hard Springs) are quite expensive. You might consider assembling them yourself from the cheaper 2909c03 (Technic Shock Absorber 9.5L with Soft Springs) and non-LEGO springs. On doctor-brick.de the following springs have been suggested:

Some indoor playing...

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Name 4WD RC Buggy
Designer Didumos
Designed 2018
Inventory 1912 parts
Theme Technic


  • 2 weeks, 2 days ago A_morti Level 6
    Awesome design, and instructions which perfectly walk the line between understandable and challenging.
    I think this model really is the pinnacle of what's possible with Technic pf parts.
    Next challenge: again using control+ motors as stressed chassis members - but it can wait till buwizz come with a control+ box!
    Thank you didumos
  • 2 months, 1 week ago Geoff Vader Level 5
    Hi. I love what you've done - the buggy is amazing. I stumbled across it about 6 months ago and, not having really touched Lego since I was younger, it inspired me to dig out my some of my old Technic Lego that was languishing in my parents garage. I didn't think much more about your buggy as I figured that I would never have all of the parts to make it. But this happened to pop up on my Amazon account the other day...
    It looks too good to be true, and the fact that this (or any other models by Guoguo) doesn't have any reviews makes me even more suspicious. If it is legitimate then I'm assuming that you must know about it? If I purchase this will I really have all of the parts to make your buggy? Then all that I would need to do is buy the instructions? Any help would be very much appreciated and congratulations again on a fantastic MOC.
    Kind Regards
    • 2 months, 1 week ago veyniac Level 17 MOC Designer PRO
      You should NOT buy the amazon model. It is NOT endorsed by the creator of this MOC, and is NOT real Lego. Guoguo appears to be a Chinese knock-off company that steals MOC designs from this site. They buy the instructions from the designers, build the set, then copy and sell it. This is ILLEGAL! Guoguo is also selling MOCs from other designers on this site, including Loxlego's Hoonicorn.
      • 2 months, 1 week ago Geoff Vader Level 5
        Hi Veyniac
        And thanks for filling me in. Much appreciated. It all seemed a bit too good to be true. You live and learn. 
        • 2 months, 1 week ago veyniac Level 17 MOC Designer PRO
          You are welcome! I always like to answer people's questions!
        • 2 weeks, 2 days ago A_morti Level 6
          I bought a similar kit and built it from didumos's instructions. There were a few small issues (tight shocks being maybe the worst), but overall the parts were decent quality and cheap compared to original Lego, and didumos still gets recognition and payment from me.
  • 4 months, 1 week ago alienwar9 Level 3
    Awesome MOC! Just got the instructions and all the parts off the parts list. About half way through the build, I'm a little confused. The parts list shows 12x Technic beam 1x13, but I've found 14 used in the instructions (5x each rear wheel (step 270+), 1 by each Buwizz container area (step 70+72), 1 centerline under the nose (step 104), and 1 later on (step 518).
    Am I doing something wrong or is the parts list incorrect?
    • 2 weeks, 3 days ago A_morti Level 6
      The parts list also includes 2x15 liftarms too many.

      Simple fix if you don't have more 13's: on pages 301+347 - use 15's instead of 13's.
  • 6 months, 2 weeks ago andrew.no Level 12
    Hi! Almost finished, just waiting for some white liftarms to look perfect, I like in the meantime to summarize my personal experience...
    The Buggy was the most challenging MOC I have ever rebuilt. I loved especially assembling the frontal steering/power unit... and the wheel hubs....Genius! While playing I wasn't disappointed. This Buggy deserves it's name and delivered what it promised: pure fun!
    The instruction are easy to follow though some steps can be tricky if you have two left hands like me but are definitely worth to pay for. Unfortunately the 2 Buwizz are well integrated and to remove the Buwizz for other creations is more than just removing a few pins...:-(
    Didomus, you are a star and I look forward to your next creations!!!
  • 7 months, 2 weeks ago andrew.no Level 12
    Hi, this a great MOC and already a while one of my favorites. It seems that also LEPIN likes it as you can by the whole set now ;-) I'm currently thinking of building it in proper LEGO, just wonder if the latest version of your instructions will be up to date or if the comments still need to be taken care of?
    • 7 months, 2 weeks ago Didumos Level 13 Designed this MOC DESIGNER
      The instructions are up-to-date. It is advisable to incorporate the set-screws right away though.
      • 7 months, 1 week ago andrew.no Level 12
        Checked. Thx for reply. One more thing: how easily can the 2 BuWizz be removed for using other MOCs parallel to the Buggy?
  • 7 months, 4 weeks ago Nick3 Level 12
    That is an very nice design!
  • 8 months, 1 week ago JustaKidWithaBrain Level 7
    Alright, I have experience building and driving real buggies such as this, and although I haven't actually built this MOC, I can tell you it is darn close to the real thing. (except for the speed, but I know how limited the options are when it comes to getting legos going fast.) I do have a question though: I have the 9398 set, so I know how hard those coil-overs are; and that MOC must real darn heavy to get four pairs of them acting so fluidly. How heavy is it?
    • 2 weeks, 2 days ago A_morti Level 6
      It's right around 2kg.
      The trick is the shocks are laid flat, which gives quite a bit of leverage over the shock.
  • 9 months, 1 week ago ghostjuza Level 5
    I started my building this week ... awesome construction ... hammer !!! In some places, though a fumbling ... but this Model is my best and funniest build so far ...
    This reminds me of my childhood when I put together the model 1:10 scale of Tamiya (Thunder Dragon) ...
  • 10 months, 1 week ago sh00ks Level 8
    Don't post much, but this post was needed out of respect:
    I take my hat off to you, sir! What a brilliantly done design! I love the looks, the mean and awesome stance really makes her a beast to behold. The applied techniques are stunningly innovative, so pleasingly different from the Lego approach. 
    The build was even more jaw dropping! I loved the enormous complexity on some parts, utilizing pincet, pliers and a sh*tload of patience, rewarded with a ego boosting feeling 😁 I'm not an experienced Technic builder like most here, but the overall build experience was twice as good than what I was used by Lego standards!
    The playability is better than I expected: it runs over all obstacles really smooth and nimble. Running on Ludacris juice is just ludacris fun, a real challenge running indoors. The robustness of the buggy is amazing too! A lot of unintended bumping on pretty high speeds and zero F's are given by the buggy. Also very protected from being chased after and grabbed by my 4 year old 😎
    I did have some failures while driving it, but nothing that wasn't instructed before hand (ball joint and front drive couplings). 
    Only thing I would like to see changed is the advice on screwing the ball joints tight with set screws: now it advices to do it when intended to ride the buggy rough and hard. My experience was that the ball joint popped loose on a slow steering manouver ending with a slight bump and to fix it took quite some time cause of the sturdy construction. IMHO the better advice would be to place the set screws as a de facto.

    Again, my deep respects for this brilliant model and many thanks for sharing your amazingly professional Lego skills! 
    Keep 'm coming please 😍
    • 10 months, 1 week ago Didumos Level 13 Designed this MOC DESIGNER
      Thanks for this elaborate report! I will take your advice and place the set screws as a de facto.
      • 9 months, 2 weeks ago [email protected] Level 12
        Hi, I am also experiencing them ball joint couplings disconnecting or in quite some cases disintegrating. Could you please elaborate on the screw solution? I'm not quite clear on the position of the screws and bricks you would want to apply these to.
  • 11 months ago erandapet Level 5
    Started building this last weekend :) Amazing build :) Thanks a lot for all your hard work :) I'm very much enjoying the build :0
  • 11 months ago nigel1975 Level 24 PRO
    Wow, I built this as per instructions (with new rims) and I'm really impressed with how solid this build is, a great example of what can be achieved with Technic. A difficult build in places and requires at least some long nosed pliers to get some pieces in place. I'm actually thinking that this may be the first time I will need instructions to take apart a MOC!  

    The MOC also looks great and plays well in terms of the PF functions and suspension. Main issue I had with the build are the Technic Universal Joint 3L's on the front wheels which break very easily. Had to swap these out a couple of times even at normal speed on the BuWizz. To really make this work it would be great if the BuWizz interface had the option to customize the speed setting selector i.e. have it as a 4-speed electronic gearshift or as paddles that could be place either side of the interface. Alternatively if anyone knows of metal universal joints that don't break so easily.

    Overall a great MOC and great fun to play. Definitely happy I bought my BuWizz, however I'm quickly learning that MOC's need to be very strong and there will be a lot of wear on parts.

    One improvement on the instructions would be to annotate the axle lengths as a bit of guesswork is involved.
  • 11 months, 3 weeks ago Jorre79 Level 16 PRO
    Thanks for sharing the new wheel assembly, works great!
  • 12 months ago [email protected] Level 12
    Finished building it today after finally getting my backordered buwizzes. Man what a solid build. Really well done!
    The instructions are really well done too.
  • 1 year ago dracarys Level 3
    Hello Didumos,

    have you used two 64712 Power Miners wheels opposite for Third Party Tires 2.2 at your MOC?

    e.g. RC4WD Z-T0079 Interco IROK 2.2 Super Swamper Scale Tire
  • 1 year, 2 months ago striker12 Level 8
    What does the inner tire do?  
    • 1 year ago Didumos Level 13 Designed this MOC DESIGNER
      It made sure the outer tire was squeezed against the large turn-table that serves as a wheel hub. However, I just updated the instructions and inventory to reflect an improved and more simple way to secure the rims to the large turn-tables, without using inner tires. This also allows for the use of third party tires without making compromises towards the rigidity of the rim-hub connection.

      I also made mod-instructions for existing builds: https://photos.app.goo.gl/nAw92pxpnCykSkSj8
  • 1 year, 3 months ago Calvin_McG Level 3 PRO
    Just finished building this, only to find out that the app won't pair to both bricks at once. Either one individually is fine, but not both. Hopefully BuWizz support can get back to me because this MOC really does not want to run in two wheel drive configuration.
    • 1 year ago Didumos Level 13 Designed this MOC DESIGNER
      I have had issues with connecting (not pairing) the App to two Buwizzes too, but only on Apple devices. On my android phones all works fine. If you want to complain about the Buwizz app, please contact Buwizz.
  • 1 year, 3 months ago Legozen Level 3
    Thanks Didumos for such a great design. I have one question: when setting up my BUWIZZ remote, the center position on the remote for the steering automatically sets the wheels to the full right position as against straight/center wheel position.  Can you think of any reasons it would do this?

    • 1 year ago Didumos Level 13 Designed this MOC DESIGNER
      Probably because the servo was not centered - or got un-centered - while building. You need to take the front apart to correct it.
  • 1 year, 3 months ago Jorre79 Level 16 PRO
    The building process was an amazing journey!
    But the playability is also fantastic, what a machine, what a performance.
    I did the first test drive on the 7th of december. After the first crash the wishbone from the steering system lost connection of the towball. The day after, I saw your update and I fixed the problem with the litlle screws. Now everything is fine! Thanks! ;-)
    I also thought the greyhound was screaming for some working lights; I added them on the roof. You can check my uploaded pictures.
    Thanks again Didumos!! Fantastic job!!
    • 1 year, 3 months ago MultiDoc Level 8
      Those tyres look great 👍 which are they ?
      • 1 year, 3 months ago Jorre79 Level 16 PRO
        Thx, unfortunately, they're not LEGO.
        It are "rock crusher" tires from RC4WD 

        The rims are from the 4199 set
        • 1 year, 3 months ago MultiDoc Level 8
          I thought so, in fact I just received 8 of these that I plan on installing on a Tatra I’m building. Think I’ll give them a try on this buggy too.
          any chance for a close up photo of how you have them installed on the rim please ? 
          Do you have the foam inside too ?
          • 1 year, 2 months ago Jorre79 Level 16 PRO
            Yes the foam is inside. I think it makes the tires a bit "stiffer" so more grip.
            I suppose photos of the attachment on the rims are not necessary since it's just the same as LEGO tires? Although it's a fact that this 3rd party tires don't fit 100%. But good enough to perform sufficiently!
    • 1 year, 3 months ago Didumos Level 13 Designed this MOC DESIGNER
      You're welcome! And thanks for your feedback! Those tires are indeed very cool. What is this light gray stripe between the rim and the tire? And are these tires squeezed against the turn-tables just like the CLAAS tires do?
      • 1 year, 3 months ago Jorre79 Level 16 PRO
        The light grey stripe is in fact white. It's printed on the rims from the 41999 set.
        I didn't put the claas-tires on the car (although I prepared them with the race tires inside ;-)), so I can't compare.
        Since the RC4WD tires are very flexible I can squeeze them pretty close to the turntables. They have a LOT of grip!
        • 1 year, 3 months ago Didumos Level 13 Designed this MOC DESIGNER
          For me it was really important to get the tires squeezed to the turn-tables, to get a stable whole. I would really be interested in how your setup compares to my design. Perhaps it would also make sense to have the race tires inside your tires, to make it more stable. Would be really cool if you could try a few things. I'm especially interested for my next build. The tires you use would look great
          • 1 year, 2 months ago Jorre79 Level 16 PRO
            Like you suggested, I tried a few options: my original setup, RC4WD tires with the LEGO race tires inside and your setup.
            It's clear now that integrating the race tires is a must do!  I think the CLAAS tires are the best option because they don't "squeeze" as much as the 3rd party ones so there's less load on the L-motors which results in faster and better performance. 
            Because of their grip the 3rd party tires tend to pull the rims away from the wheelhubs when turning fast in ludicrous mode.
            For your current project, the RC4WD tires could be an option because I saw you switched to standard LEGO wheelhubs instead of the turntables. When it would be a Zaroq, they would look nice!! Anyway, you make me very curious about it...!! ;-)
    • 1 year, 2 months ago jdcasta03 Level 9
      hi Jorre79,
      can you please show where the towball are to be fixed? 
      thank you
      • 1 year, 2 months ago Jorre79 Level 16 PRO
        I uploaded a photo but it's not that clear where the towballs are located.
        It's connected with the 57515 steering arm which you can see and the 63869 axle/pin connector which you cannot see on the picture.
        I hope you can find it!
        • 1 year, 2 months ago jdcasta03 Level 9
          it really helped me your Picture...

          thank you
    • 1 year ago Didumos Level 13 Designed this MOC DESIGNER
      I just updated the instructions and inventory to reflect an improved and more simple way to secure the rims to the large turn-tables, without using inner tires. This also allows for the use of third party tires without making compromises towards the rigidity of the rim-hub connection.

      I also made mod-instructions for existing builds: https://photos.app.goo.gl/nAw92pxpnCykSkSj8https://photos.app.goo.gl/nAw92pxpnCykSkSj8
  • 1 year, 3 months ago JESUSWARRIOR777 Level 7
    I already purchased the instructions and am looking forward to building this great beast! I know it will be awesome! The one thing I am having trouble with is what you said to do with the shock absorber springs. Is there anyway you could elaborate more on the type of spring you suggested to use as a hard replacement for the softer spring. It is all in German and I have no Idea how to translate the Germans springs measurements to an Americans  springs measurement to match it.
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