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Jeep Wrangler Rubicon

April 20th, 2010 Leave a comment Go to comments

Jeep Wrangler Rubicon
My second 2010 Truck Trial vehicle, and the first vehicle designed for this competition other than a truck. Features 4×4 drive, pendular suspension, lights, modular body design and an openable bonnet. Update: a complete set of instructions added.


Completion date: 18/04/2010
Power: electric (Power Functions)
Dimensions: length 47 studs / width 24 studs / height 23 studs
Weight: 1.224 kg
Suspension: pendular, stabilized with 2 shock absorbers per axle
Motors: 1 x PF Medium, 1 x PF XL

After the disappointing failure of my Tatra T815 truck, I was left with less than two weeks time until the next race. Re-using Tatra was out of the question, so my only option was to build some simple and small 4×4 vehicle. Since our current rules allow this type of vehicle into competition, I decided to model the iconic Jeep Wrangler in the acclaimed Rubicon version. It was built in roughly 4 days.

The basic rule of this construction was to keep everything as simple as possible and to reduce the weight to minimum. This is why the body was built with the new Technic panels, which provide the best combination of stiffness and lightness. Both front and rear axle are built entirely with liftarms, but the frame that connects them is built with Technic bricks. The reason to use bricks was that I wanted to build a roofless version of the Jeep in order to obtain low center of gravity, and since the sides of the cabin are made of single panels, the whole model had to be kept together by the cabin’s floor. Therefore there are bricks in the floor, that provide excellent stiffness and robustness while keeping the floor thin.

The chassis, which weights just 0.75 kg, consists basically of the studfull frame connected with studless axles. Since there is very little space in front of the front axle, both drive and steering had to be transferred to the front axle from behind. This was achieved by placing a 16-teeth gear with a clutch on the driveshaft – this gear works as an idler gear between two other gears, thus transferring the steering independently to the drive. Front axle is compact but massive, strong enough to handle much heavier vehicle, and it’s bottom is entirely covered with liftarms to prevent it from getting stuck on an obstacle. It should be noted that both axles use knob wheels instead of differentials, and both are portal axles with an integrated 3:1 gear reduction. Each axle is stabilized by a pair of short shock absorbers located between the axle and the frame for maximum structural integrity. In order to minimize the effect of central driveshaft’s torque tilting the body, which occurs when only pendular axles are used, the axles are stabilized with the hardest shock absorbers available. The rear axle is built around the 7×5 liftarm frame and is not covered from below.

The model is driven by a single PF XL motor with a total 5:1 gear reduction, and the motor’s location is strictly related to our current rules. Our rules state that every model has to be equipped with a piston engine whose set-up and location are consistent with the original engine. This rule, however, can be omitted if the drive motor is located exactly where the original engine is. This is Jeep’s case – the PF XL motor occupies exactly the same place that is taken by the original engine in a real Jeep, hence there is no need for the piston engine and the model can be simpler and lighter. You can see the top ends of the front axle’s shock absorbers next to the motor. It should be noted that the PF XL motor actually touches the front axle, but because it’s located in the center of the chassis and because it has a round shape, the axle can still oscillate under it. Such a trick was necessary to fit the XL motor under the bonnet.

The steering is controlled by a PF Medium motor with a 9:1 gear reduction. The motor is located between the seats in the cabin, and the steering wheel is connected to it. The cabin has a safety cage built on top of it, which is strong enough to survive a turnover without any damage. Finally, there is the 8878 rechargeable battery box and the IR receiver located over the rear axle, as a counterweight against the PF XL over the front axle.

One special feature of the bodywork is a droppable modules design. The obstacles used in our races are often larger than the ones the real vehicles are designed for, so the usual practice to handle this difference is to increase the model’s ground clearance. I wanted to avoid it, however, to keep the Jeep’s center of gravity as low as possible. It meant that some parts of the body are very likely to touch the ground e.g.  when the approach angle proves to be insufficient. Therefore I designed a number of body elements as independent modules that would fall off when stressed, on assumption that it’s better to drop something than let it get the whole vehicle stuck. The list of droppable elements includes front and rear bumper, rear spare wheel and front mudguards. The sides of the cabin are somewhat elastic too. This design is also helpful when the front wheels’ steering lock makes them collide into some parts of the body.

The model turned out to be pretty stable, with a well performing suspension and an excellent amount of torque available. It was my goal to prefer the torque over speed, since I did not want the model to get stalled under any circumstances while its speed didn’t seem crucial. This is second model of a Jeep used in our races, and it’s much different from its predecessor, the Jeep Willys built by Atr. Among other things it is heavier, larger and slower. Observing the two models compete against each other and comparing their performance will be certainly a great experience.

The main disadvantage of this model is its size. The standard scale used for vehicles in our races is 1/13. I was in hurry while building the Jeep, so I picked up the wheels I found most suitable and scaled the whole model accordingly to their size. Eventually it turned out to be in 9/1 scale which is much different from the required one, and will probably result in letting this model race outside the official ranking (in a so-called ‘open class’). Still, building and testing this model was a valuable experience, and driving it in a race will be so too. It was also acclaimed by other builders and race contestants for its look, its authenticity and its performance. If it turns out to be successful in the race (meaning that it suffers no fatal malfunction and doesn’t end up last), I will prepare and publish a complete step-by-step instruction for it, as well as schemes of front and rear axle along with their individual instructions.

Update: since the Jeep performed well at the race, the instructions are under the photos.


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Full instruction with parts list:

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Photo-instruction for the whole model:

001.jpg 002.jpg 003.jpg 004.jpg 005.jpg 006.jpg 007.jpg 008.jpg 009.jpg 010.jpg 011.jpg 012.jpg 013.jpg 014.jpg 015.jpg 016.jpg 017.jpg 018.jpg 019.jpg 020.jpg 021.jpg 022.jpg 023.jpg 024.jpg 025.jpg 026.jpg 027.jpg 028.jpg 029.jpg 030.jpg 031.jpg 032.jpg 033.jpg 034.jpg 035.png 036.png 037.png 038.png 039.png 040.png 041.png 042.png 043.png 044.png 045.png 046.png 047.png 048.png 049.png 050.png 051.png 052.png 053.png 054.png 055.png 056.png 057.png 058.png 059.png 060.png 061.png 062.png 063.jpg 064.jpg 065.jpg 066.jpg 067.jpg 068.jpg 069.jpg 070.jpg 071.jpg 072.jpg 073.jpg 074.jpg 075.jpg 076.jpg 077.jpg 078.jpg 079.jpg 080.jpg 081.jpg 082.jpg 083.jpg 084.jpg 085.jpg 086.jpg 087.jpg 088.jpg 089.jpg 090.jpg 091.jpg 092.jpg 093.jpg 094.jpg 095.jpg 096.jpg 097.jpg 098.jpg 099.jpg 100.jpg 101.jpg 102.jpg 103.jpg 104.jpg 105.jpg 106.jpg 107.jpg 108.jpg 109.jpg 110.jpg 111.jpg 112.jpg 113.jpg 114.jpg 115.jpg 116.jpg 117.jpg 118.jpg 119.jpg 120.jpg 121.jpg 122.jpg 123.jpg 124.jpg 125.jpg 126.jpg 127.jpg 128.jpg 129.jpg 130.jpg 131.jpg 132.jpg 133.jpg 134.jpg 135.jpg 136.jpg 137.jpg 138.jpg 139.jpg 140.jpg 141.jpg 142.jpg 143.jpg 144.jpg 145.jpg 146.jpg 147.jpg 148.jpg 149.jpg 150.jpg 151.jpg 152.jpg 153.jpg 154.jpg 155.jpg 156.jpg 157.jpg 158.jpg 159.jpg 160.jpg 161.jpg 162.jpg 163.jpg 164.jpg 165.jpg 166.jpg 167.jpg 168.jpg 169.jpg 170.jpg 171.jpg 172.jpg 173.jpg 174.jpg 175.jpg 176.jpg 177.jpg 178.jpg 179.jpg


Media reference:

AutoMotto, GadgetSin

Categories: Cars, Truck Trial Tags: , , ,
  1. Sariel
    August 2nd, 2015 at 17:23 | #1

    @Myeong Mo Kim
    I think it’s the most accurate I was able to find, but probably not a perfect one.

  2. Myeong Mo Kim
    August 2nd, 2015 at 06:23 | #2

    Sariel, Is that blueprint in the instructions accurate? I found the same one in here(http://www.the-blueprints.com/blueprints/cars/jeep/20701/view/jeep_wrangler_rubicon_/) and found out that some of the wheel sizes are different(e.g. spare wheel and wheels attached to a axle). I’m searching for a accurate jeep wrangler blueprint in the internet and its quite hard…

  3. Pablo Salamanca
    February 20th, 2015 at 18:45 | #3


  4. Sariel
  5. Pablo salamanca
    February 5th, 2015 at 16:41 | #5

    Hi can anyone tell me how are called the yellow “gears” he used for the differential because I can’t find them on Bricklink.

  6. Sariel
    December 18th, 2014 at 09:19 | #6
  7. Mario
    December 18th, 2014 at 03:03 | #7

    Hello, Great build. What is your advise in getting all these parts? Is there a current kit that has most of them? I want to build this! What was the cost if you don’t have the extra parts? Thank You

  8. Sariel
    December 3rd, 2014 at 19:08 | #8

    No, it’s 1:5.001 to be correct. I even made a tool for you to calculate it, to be correct: http://gears.sariel.pl/

  9. EV3fan
    December 3rd, 2014 at 17:22 | #9

    Thank you. I thought it was different because you wrote 5:1 but it’s 5.5 and something : 1 to be correct.

  10. Sariel
    December 2nd, 2014 at 18:38 | #10

    8t -> 24t + 12t -> 20t.

  11. EV3fan
    December 2nd, 2014 at 17:31 | #11

    Just a little question: Do you remember how the 5:1 reduction was achieved here? With an 8-tooth gear connected to a 16 – tooth gear and an 8-tooth gear connected to a 24-tooth gear or else?
    Thank you!

  12. TecHUNic
    October 30th, 2014 at 17:46 | #12


    Thanks for the clarification. You are right, probably GP sucks here. Will try with proper 1.2V batteries (I’ve just got my hands on 6xAA Eneloops and a 8881 Battery Box) before buying a 8878 then.

    Btw, watching your indoor video above again, just realized that my Jeep is way too slow (even with the 6x AAA 1.5V alkaline) compared to yours. Maybe I got some gear problem, it does not seem to run smooth all the time. My speed is about 10-11 cm/sec, and looks much less than yours.

    Anyway, here is a picture of my original black version: http://i.imgur.com/uWzQ3sU.jpg


  13. Sariel
    October 30th, 2014 at 00:10 | #13

    No, this is the exact opposite of what I told you. Torque is always the same, no matter what batteries, no matter what voltage. It’s only the speed that gets higher with higher voltage. So 8878 will be slower than 1.5 V batteries, but with the same torque. Like I said, your GP batteries are probably worn down, the same happened to mine. GP sucks, that’s why I switched to Eneloops.

  14. TecHUNic
    October 29th, 2014 at 23:03 | #14


    So you say that 8878 drives this beauty at least as fast as the 88000 with 1.5 V batteries? Torque is crazy when using 1.5 V (climbs ANYTHING in its way), but honestly I did not test it with the GP rechargeables as whole Jeep was like a dead turtle.

  15. Sariel
    October 29th, 2014 at 20:05 | #15

    The voltage does not affect torque, only speed. The problem must be your GP batteries.

  16. TecHUNic
    October 29th, 2014 at 19:24 | #16

    Hi, Sariel! I’ve just finished building this awesome Jeep WR in black with light bluish grey accent matching gears, pins etc. Super cool when it is about displaying but had to mod chassis it a bit to get smoother steering (front bumper and side front panels were in the way when turning wheels near the end points). Maybe it was just me sucked at following instructions. Anyway, I’d like to ask you about the best solution to power this badass Jeep with. I’m currently using 88000 AAA Battery Box with 1.5 V alkaline batteries. Putting in 1.2 V Rechargeable 900 mAh GP batteries is a complete failure (barely moves the Jeep)! Is this possible that 7.2 V gives not enough power for moving this beast? If so, how can it be, that the 7.4 V Rechargeable 8878 can drive it well (I assume you used 8878 int he videos you shared). Watched your Battery Box comparison video, but did not help to decide. I’m about to buy a 8878, but don’t want to find it useless. Thanks for any response in advance!

  17. Bridger
    October 23rd, 2014 at 21:17 | #17

    Ok thanks so much! U love this jeep and your hamsters!

  18. Sariel
    October 23rd, 2014 at 21:15 | #18

    Smaller wheels will improve performance.

  19. Bridger
    October 23rd, 2014 at 21:13 | #19

    @Sariel ok an is there any way to give it more torque?

  20. Sariel
  21. Bridger
    October 23rd, 2014 at 20:41 | #21

    @Sariel ok I’ll get smaller tires and thanks

  22. Sariel
    October 21st, 2014 at 09:34 | #22

    You must have done something wrong. Sounds like you used different, larger wheels.

  23. bridger
    October 21st, 2014 at 02:24 | #23

    hi! i built this and i have problems with my tries getting stuck inside the wheel wells. also not having the power to climb things like the stuff in your video.

    thanks, bridger

  24. Sariel
    July 19th, 2014 at 09:50 | #24


  25. Jeff
    July 19th, 2014 at 01:31 | #25

    Hi sariel!
    Im considering building this model but im wondering if there is any gear cracking or ‘slippage’
    Is there any?

  26. Sariel
  27. Zach
    January 24th, 2014 at 13:37 | #27

    What part number tires are you using?

  28. Sariel
    January 20th, 2014 at 09:09 | #28


  29. Zach
    January 19th, 2014 at 23:32 | #29

    Could you change out the rechargeable battery pack, the one running it, with the battery box

  30. Sariel
    January 19th, 2014 at 03:57 | #30


  31. Zach
    January 18th, 2014 at 22:59 | #31

    Could you change the rechargeable battery with the cheapest one you can buy?

  32. Sariel
    January 4th, 2014 at 00:19 | #32


  33. Zach
    January 3rd, 2014 at 23:42 | #33

    Do you know a place where I can buy individual pieces for this like the red body plates

  34. Zach
    January 3rd, 2014 at 20:59 | #34

    Wow! Awesome job sariel. I’m a big fan

  35. Sariel
    October 8th, 2013 at 11:27 | #35

    Sure, thanks.

  36. October 8th, 2013 at 10:20 | #36

    Hello Sariel,

    I just came across your MOC on Rebrickable. I really like the look of it, and thanks for making instructions available.. I know how much time is involved in creating those. It’s appreciated. I’ve downloaded all the individual PNGs and turned them into a single PDF, for ease of use. Are you OK with me distributing this PDF to people who want to build this model? With all credit to you, ofcourse.


    Jantjeuh (from Eurobricks)

  37. gabry
    January 1st, 2013 at 15:29 | #37

    Oh, now I understand what you are talking about! But I’ve built some different mudguards, they can’t touch the wheels anyway. However I think to destroy it and build a new truck. I’m sad now. “Bye bye Jeep” ;(
    I take this occasion to thank you for inspire and help me often, Sariel. I hope to meet you someday, if you’ll come to Italy… Keep calm, I’m joking!

  38. Sariel
    January 1st, 2013 at 15:17 | #38

    Turned so far left or right that it’s not possible to turn more in that direction.

  39. gabry
    January 1st, 2013 at 15:16 | #39

    The steering system is OK, but what do you mean with “wheels turned to maximum”?

  40. Sariel
    January 1st, 2013 at 10:35 | #40

    No. Are you sure this doesn’t happen when the wheels are turned to maximum? Or perhaps the 16t gears responsible for steering between the axle and the chassis come apart?

  41. gabry
    December 31st, 2012 at 19:23 | #41

    Hi Sariel! I used the axles of your great Jeep Wrangler Rubicon in my custom Jeep Wrangler Sahara, and sometimes, while the car meets an obstacle and sometimes when the front axle is steered, I hear some alarming “Clicks” and other noises. At first I tried to locate the cause of these noises but Ididn’t find it, so I disassembled a part of the model to check the gears: everything was in its place (and I followed all the tips given by your book). Now I suspect that there is a problem in the hubs of the rear axle. Did you have any problems with your jeep?

  42. Sariel
    December 12th, 2012 at 11:44 | #42

    I have no idea.

  43. jeremy
    December 12th, 2012 at 10:52 | #43

    around what cost would this take to buy all new parts from LEGO??

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  1. June 27th, 2013 at 15:51 | #1