4WD RC Buggy - Orange

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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!

Update
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:



Background
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.

Important
-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.
-In the instructions replace all white and medium blue parts by orange parts, except for the white center stripe in the bodywork and in the center column. Also replace the two black small panels at the back of the roof with orange ones.
-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.

Features
-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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MOC-19664

Name 4WD RC Buggy - Orange
Designer Didumos
Designed 2018
Inventory 1912 parts
Theme Technic
Old Trafford

22 COMMENTS

  • 2 months, 2 weeks ago astyanax Level 12 PRO
    Beste Diederik, is there any reason why you use universal joints (part 61903) at the front wheels, instead of CV joints (parts 32494 & 92906)? I see others commenting that the universal joints are prone to breaking; would CV joints fare better?
    • 2 months, 2 weeks ago Didumos Level 13 Designed this MOC DESIGNER
      CV-joints would only allow for a steering angle of max 20 degrees, whilst this model has a max steering angle of over 30 degrees. Universal joints are prone to breaking, but with the power from the BuWizz, CV-joints are even more likely to slip and eventually deteriorate, as the male half gradually drills a hole in the female half. The newer CV-joints from 42099 are better though. At least the U-joints don't slip, so they are fun until they break. CV-joints slip fairly easily, so they give much more annoyance. I added silicon bands around the bushes of the U-joints to prevent them from breaking. It really helps, but the weak section remains to be the center of the U-joint. After I finished this model I only broke 1 U-joint so far.
  • 9 months, 2 weeks ago willem205 Level 3
    Hi there,
    Great moc! I'm planning to buy your instructions, but since there are 2 buwizz units in it which have to work at the same time I have a question. Currently I've improved the red crane truck with 2 buwizz units as well, but it seems they can only be controlled after one another, it's not possible at the same time. I'm using an Iphone and heard this could be the problem (apple instead of android). Do you know of this problem? Your buggy needs controlling both buwizz units at the same time, so.. Hopefully you can advice me in this. Greetings,Willem
    • 9 months ago Jorre79 Level 16 PRO
      Hi,
      It should be no problem to use both BuWizzes at the same time when you use the Crane profile in the BuWizz app. Then you can customize the control panel. I use an iPhone 5 and an iPhone 7; it works fine with both of them!
    • 9 months ago nigel1975 Level 24 PRO
      I had issues with the iPhone XR, both BuWizz will connect, but one or the other will keep loosing connection. Seems unable to maintain continuous signal to both BuWizz at the same time when powering all four motors. I have to keep restarting the app but only get 5-10s at best. Would be interested to here if anyone else has issues. Do not have this issue with 2x SBrick and four motors.
  • 9 months, 2 weeks 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 DiegoCola Level 9
    It looks amazing, thank you very much for your work! :)
  • 1 year ago Slim Level 5
    SO I bought the plan recetnly even though I dont have the necessary parts. At the moment Im trying to build it via Stud.io and so far I must say that the plan is perfectly done. Hope I get enough cash soon to buy the parts and build it.
    • 1 year ago Peto98 Level 4
      I don't have parts too I'm wondering if it's worth to buy plan and try to rebuild it with own parts
  • 1 year, 1 month ago GymmeFyve Level 6 PRO
    He has become really great! I especially like the suspension very well done. Already close to the normal RC model. Keep it up!
  • 1 year, 1 month ago Rockpoint Level 8 MOC Designer
    This is a superb piece of engineering, well done! I want to study your connects and construction, it answers many of the questions I have about the optimum design for this kind of application. 

    Congratulations!
  • 1 year, 2 months ago rho76 Level 10
    Does your MOC also run on a a standard battery box (16511)?
    I know it will not be as fast and I'll have to swap batteries quite often. But I'm afraid the power available won't be enough to get it even moving.
    • 1 year, 2 months ago lego_rules Level 14
      The buggy motors will trip the protection on that battery box after a very short distance.
      • 1 year, 2 months ago rho76 Level 10
        This MOC has 4 L motors. Not the buggy motors.
        • 1 year, 2 months ago lego_rules Level 14
          Yes, of course.  My apologies.
          there is a video someone did showing 2 L motors can also trip the Lego battery protection as well.  Also keep in mind that battery box is much much heavier than a buwizz so it will change the weight distribution dramatically if you use two of those battery packs.  This also assumes you can find a place to mount them.

          You might be able to get away with two Li-PO battery pack which Lego makes but these can also trip the battery protection.
          • 1 year, 2 months ago rho76 Level 10
            Aha, OK that makes sense.
            I didn't know the Buwizz is so light-weight.

            Thanks for the explanation. :)
  • 1 year, 2 months ago grzegorz Level 9
    finished built last night...it is thing of beauty :)
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