Skip to content

Mk Ultra - 3D printable 1/10 4wd buggy

Creation's quality: 5.0/5 (14 votes)
Evaluation of members on the printability, utility, level of detail, etc.

3D model description

This is the Mk Ultra. A high performance belt driven 4WD 1/10 scale buggy. It is very sophisticated and capable. The car can withstand plenty of abuse, and is easy to repair and maintain.

You can ask questions and read about the car development here:

Here's a good source of hardware like bearings and fasteners for the car in one place:

Here's a great video by Elias F showing how he assembled his MK Ultra and even adapted some of his hardware to fit:

More videos:

Driving during development:

How to install and remove the body:

Free option parts:

The prototype runs with a 13,5T brushless sensored motor.

-Uses easy to find belts from Schumacher K1 buggy.
-Can use CV axles from multiple brands (Kyosho, Tamiya, Schumacher, Basher, Quanum, FTX and more).
-Wrap around body is held on without clips or velcro and keeps dirt out.
-Super precise steering thanks to ball bearings in all hinges.
-Small turning radius.
-Radial shock positions ensure minimal height change with shock adjustment.
-Printable high strength gear, sealed gear or ball diff option.
-Supports FS Racing steel gear diff with adapters.
-Printable 48dp pinion and spur gears.
-Printable slipper clutch option.
-Sway bar option front and rear.
-Two body styles to choose from.
-Many adjustment possibilities.
-Designed to comply with ROAR regulations.
-Easy to use shorty battery mount without clips.

Wheelbase: 283.3-289.3 mm (adjustable with different rear arms)
Width: 249 mm (With quanum Vandal front CVD's and zero camber)
Front and rear track: Adjustable with different hexes.
Final drive gear ratio: 2.125:1 with 16t layshaft. 2:1 with 17t layshaft
Chassis length: 358.5 mm

Assembly notes:
-Option parts to use FS racing steel gear diff (Part 511687) can be made, though they aren't needed in my opinion, as the printable gear diff has not caused problems for me at all. The pulley part replaces the outside bevel gear on the FS diff and the spacers are used inside the 12x18x4 bearings on each side of the diff. This diff works with CVD shafts that have <2 mm pin and <6mm ball on the dogbone end.
-The Spindlefront02-Ackerman and Steering02-Ackerman steering and spindle pieces add more ackerman-compensation than the stock parts.
-Universal adjustable 110-120mm CVDs can be used now. The option files have spindlerear and spindlefront 110-120 names. The rear one needs to be filed and shortened slightly, but this is easy to do and takes seconds with a file and bolt cutter. Look at the added photo for examples of the work.
-If you can't find CVD axles of the right length then it's possible to order ones that are too long and then cut them shorter and silver solder/braze or weld together. I have done this myself with vintage cars that don't have parts available any more. If you don't have the ability to braze you can use a shaft coupler like this:
-CVD axles with short wheel axles can use the file "Option - Spindlerear-shortaxle.STLOption - Spindlerear-shortaxle.STL" instead of the regular rear spindles. These are only 10 mm thich from bearing to bearing.
-The sealed diffs are the strongest. They use 20 inner diameterx2mm O-rings to keep the grease in. They are not intended to be filled with silicone fluid, but rather made to keep the grease in.
-Removing the support pieces from the diff parts easily:
-Do not over tighten any screws. Screws threaded into plastic only need to be snug. Stripped threads can be refreshed with a thin layer of CA glue, or just reprint the parts. That's the cool thing about printed cars.
-A PLA motor mounting plate can deform if the motor gets hot. If this is a problem, print the motor plate from PETG, ABS or nylon, or another more heat resistant material.
-The middle piece of the motor mount assembly has two small holes for mounting a small 25 mm fan. It will aid with motor cooling by circulating air inside the body and directing it over the motor.
-I recommend using a gear diff in the rear if it's difficult to avoid slip. If the ball diff screw comes loos while driving I recommend adding a drop of thin CA on the end with the nut after tightening to the correct tension. The nature of PLA is such that it can deform over time and loosen the diff.
-Ball diffs must not slip noticeably. If they do the pulley part of the diff will deform from heat. To adjust the diff tension loosen the camber link on the side where the bolt head is, insert an allen wrench and turn the opposite wheel to tighten or loosen.
-If the ball diff tension loosens, add a drop of thin CA to the nut end of the diff after adjusting.
-Gear diffs spin more freely than ball diffs. Use this info to tune the car. A good starting point is gear in the rear and ball in the front. The gear diffs are called Gearediff. The gear diffs should not have a lot of side to side play in the seats in the chassis, or they will break. Print "Diffspacer.STL" to adjust this play. Diffspacer.stl canbe scaled in the Z-axis to make it thicker.

-Suggested setting for links. Measured on outer ends:
Front camber links: 67mm
Steering links: 69 mm
Rear camber links: 77 mm
I suggest starting off with the link in the innermost and uppermost holes.
-The option parts contain various rear spindles and pivot blocks for changing the rear anti squat or toe in. The amount is marked on the parts and should be visible after printing.
-I suggest starting with the shocks in the center holes on both top and bottom.
-The shock adapters allow the use of aftermarket big bore springs with the suggested shocks below. The stock springs are too hard.
-The printable shock pistons are an upgrade from the ones included with the cheap shocks. I suggest one hole and ~550 CST shock oil for starters. It depends on your track and temperature.
-The shock covers fit over the top of the rear shocks and screws and protect the shock from damage, while also protecting the track surface from damage.
-The rear belt tensioner pushes up on the belt to tension it. It is accessed by a central screw from the underside of the chassis.
-The printable wheels have the same offset and width as competition Schumacher wheels.
-The body can take some practice to install. The trick is to tuck the nose in first, flex the front edges of the bod around the steering posts and then it will go on quite easy. There is no need to cut to make it fit. Check the video I posted above of installing and removeing the body.
-Body01-02 is the cab forward body
-Body03-04 is the futuristic body

List of required purchases. Many links contain my affiliate code so that I get a small kickback from your purchase on the sites. It does not cost extra because of this, but helpsme out a lot:

-Minimum 2 channel transmitter and receiver. Cheap:
This is better:
-Your motor and ESC of choice? 13.5T sensored recommended.
Or the cheap option:
-A good servo:

-Spur gear. For example
Associated 48Dp:
-Servo saver. I recommend this one:
-Schumacher k1 120t and 132t belts. Also available via Ebay:

-Universal CVD's:
-Also needed are one 10x15x4 ball bearing per axle:

-Quanum vandal Front CV axles or BSR BZ-444 front CV axles (clones like FTX Vantage fit as well):

-BSR BZ-222 rear CV axles or BSR BZ-444 rear CV axles (FTX Edge, clones and other rear competition buggy CVD's should fit as well):

-Optional steel diff:

-90 mm front shocks (~81 mm eye to eye center):
-100 mm rear shocks (~91 mm eye to eye center):
-40-45 mm long 3mm tie rods for the adjustable option. Threaded rod can be used in a pinch. These fit perfectly:
-4x 18x25x0,5 washers for ball diffs:ø-6-100-mm-Shim-ring/262968954788
-30x 3mm hardened steel chrome or ceramic balls for ball diffs:
-Slipper clutch spring:

-2x 30mm diameter steel washers for slipper clutch.
-8x 12x18x4 ball bearings.
-12x 3x7x3 ball bearings.
-12x 5x11x4 ball bearings.
-2x 3x6 thrust bearings.
-2 mm piano wire to make pins.
-1.5 mm piano wire to make pins and sway bars.
-3x15 mm brass tube for rear tensioner.
-2x 3x20 mm brass tube for gear diffs.
-2x 3x28 mm brass tube for rear spindles.
-2x 3x26 mm brass tube for front spindles.
-3x34 mm brass tube for slipper clutch shaft.
-2x 3x48mm brass tube for rear suspension arms.
-2x 3x45mm brass tube for front suspension arms.

-4x M2x6 + M2 washers.
-6x M2x8.
-14x M2x12.
-10x M3x8.
-23x M3x12.
-10x M3x16.
-1x M3x20.
-2x M3x25.
-2x M3x34.
-1x M4x16
-11x M3x12 countersunk.
-5x M3x20 countersunk.
-6x M3x25 countersunk.

-15x M3 nyloc.
-4x M4 nyloc

New option parts will appear as new free items on Cults3D.

3D printing settings

Use 100% rectilinear infill, 0,2 mm layer height and two perimeters for everything except for the body and tires. The car will be very underweight for its racing class if it's not printed solid.

The slipper gear needs support.

The wheels need support on the inside. This support is easiest removed by twisting it after printing. This usually leaves a clean surface.

Use 5% infill and one perimeter for the body. The body needs support under the rear area.

I suggest 10% infill and three perimeters for the tires. Your mileage may vary as printing elastoemers is an art.

Use maximum 0,1 mm layer height for the links and balls and test fit and calibrate the printer accordingly. They will need pliers to click together the first times and should be slop free with only slight tightness at first.

My faviourte material for the rear wing is PP (Polypropylene). Use brown packaging tape on the bed for adhesion.

3D printer file information

  • 3D design format: STL, TXT, and ZIP Folder details Close
    • Armfront01.STL
    • Armrear01-SWB.STL
    • Battery01.STL
    • Body01.STL
    • Body02.STL
    • Body03.STL
    • Body04.STL
    • Chassis01-New.STL
    • Chassis02-New.STL
    • Chassis03-New.STL
    • Chassis04-New.STL
    • Chassis05.STL
    • Diffspacer.STL
    • Geardiff.STL
    • Idler01.STL
    • Layshaft16t.STL
    • Layshaft17t.STL
    • Links01.STL
    • Motormount01.STL
    • Ni-MHBody.STL
    • Option - Armrear-LWB.STL
    • Option - Armrear-MWB.STL
    • Option - Balldiff.STL
    • Option - FSdiffpulley.STL
    • Option - FSdiffspacer.STL
    • Option - Hexes.stl
    • Option - Pivotrear.stl
    • Option - Shockpistons.STL
    • Option - Slipper.STL
    • Option - Spindlefront-110-120mmAdjustableCVD.STL
    • Option - Spindlefront02-Ackerman-110-120mmAdjustableCVD.STL
    • Option - Spindlerear-110-120mmAdjustableCVD.STL
    • Option - Spindlerear-frontaxle.STL
    • Option - Spindlerear-shortaxle.STL
    • Option - Spindlerear.STL
    • Option - Swaybar.STL
    • Option - Turnbuckles.stl
    • Part description.txt
    • Pinion22t.STL
    • Pinion28t.STL
    • Pivotfront01.STL
    • Pivotrear01.stl
    • Rearshockcover01.STL
    • Servomount01.STL
    • Shockadapter01.STL
    • Shocktowerfront01-New.STL
    • Shocktowerrear01-New.STL
    • Spindlefront01.STL
    • Spindlefront02-Ackerman.stl
    • Spindlerear01.STL
    • Spur87.STL
    • Spur92.STL
    • Spur97.STL
    • Spuradapters01.STL
    • Steering01.STL
    • Steering02-Ackerman.STL
    • Tensionerfront01.STL
    • Tensionerrear02.STL
    • Tirefront01.STL
    • Tirerear01.STL
    • Wheelfront01.STL
    • Wheelrear01.STL
    • Wing01.STL
    • Wingmount01.STL

    Learn more about the formats

  • Last update: 2021/12/27 at 04:50
  • Publication date: 2017/09/15 at 21:07





Norwegian inventor/designer/cat owner.

Please don't ask for original design files or parametric files.

If you ask a question about a design, ask under the design so that I can answer there.

Issue with this design? Report a problem

Makes created by the community

Best sellers of the category Various

Add a comment


is there supposed to be a arm_front_LWB? i onlysee rear_LWB

Hello, the download link not working, it say error

Some hardware purchase links have failed, such as - spur gear pinion servo Saver - 90 mm front shocks - 100 mm rear shocks - 4x 18x25x0,5 washers for ball diff. Can you tell me which motor gear is used? I can only buy a single one here, which is very expensive!!!, And the belt can you tell me his details? I can't buy it in my place. I can only look for alternatives,

I added it. Mirror the part in your slicer to get the opposite side as needed.

@TAHUSTVEDT, thank you. Could you also do a version for the file Spindlefront02-Ackerman.stl, please? :)

You need to download the option spindles for 110-120 adjustable CVDs. Redownload the file set if you don't have them.

@TAHUSTVEDT, how do you get the universal CVD's to fit the front hubs? Are you able to design a front hub to accommodate them?

I have built one and have been running it for a while. Happy to help you along if you PM me on Facebook/here.

Man, what a fantastic project!
Honestly I would really pleased to pay some money for a detailed instruction manual (how to print, how to assemple, etc).
Do you have something like this?

@TAHUSTVEDT Takk for det! I have a further 3 questions:

-The 3mm brass that outer diameter?
-I can't find the Associated 9605 spring for sale here any more. Is there another that will fit?
-Do we need a clutch plate of some sort for the slipper clutch?

@SST99PRO I added a TXT file with part descriptions.

Heisann! Have you a document that explain what each of the STL's are? You did this with your Lynx buggy which was very useful!

The Yokomo YZ-4 SF/SF2 65mm CVDs work as rear axles for this car. The drive shaft pins that go into the outdrives are a little snug, but the axle lines up with the spindles. You just need to use the low-profile wheel nuts to secure them.

Note that these are 65mm driveshafts and 100mm in total length, so they ONLY work with the printed outdrives. If you use the metal FS Racing differentials, the outdrives are too short and will require some spacers or other modifications to the CVDs to allow them to reach properly.

I will test them and see how they work but I am just now ordering parts to assemble chassis so it will be a little bit, also great design and do you have any full assembly instructions or maybe where all the bolts go?

If they don't fit directly let me know what doesn't fit, or give me a photo with dimensions, and I'll make the new parts that make them fit.

I haven't tested them but the designer said they should work in an earlier comment and judging by the specs they should.

I am also trying to find some CVDs (and maybe alternate gear diffs) in the US. If you find any, please post here and I will do the same!

Do you have any specs or alternate for rear cvd. Looks like those listed are sold out everywhere. I am in the US and they look like impossible to get

Yes I did but I think there is a problem with that specific seller and it is very difficult to find those belts. ( I have been searching in many webs and I did not find anyone with stock.

Did you use the links to the belts in the description above? Did you try searching for more sellers?

I can not buy schumacher 120T and 132T (U4186 and U4187) because they are out of stock.
Do you know any other brand to fit ?

normal or countersunk head, on your car I see several types of screws would it be possible to say where they go exactly.

I use screws with socket allen heads. The steering bellcrank can benefit from button heads if clearance is an issue.

hello what typ of head screw are you using?

-4x M2x6 + rondelles M2.

-6x M2x8.

-14x M2x12.

-10x M3x8.

-23x M3x12.

-10x M3x16.

-1x M3x20.

-2x M3x25.

-2x M3x34.

-1x M4x16

-11x M3x12 contrepercé.

-5x M3x20 contrepercé.

-6x M3x25 contrepercé.

Des noix :

-15x M3 nyloc.

-4x M4 nyloc

Just brilliant!

I've added parts now to adapt an FS Racing steel gear diff (FS part number 511687) for use with this car. The diff works together with CVD shafts or dogbone shafts with <2 mm pins and <6 mm ball on the dogbone end. A printable pulley replaces the external gear that the diff comes with, as pictured in the photo with the bag.

I have also researched different CVD brands to find suitable ones. It looks like many can be used. Schumacher CAT CVD's, Kyosho ZX6 CVD'z, Tamiya Top Force CVD's and probably many many more seem to be suitable. There might be a need to shim slightly, but that's easy to do with printable shims like the one that is used for BSR BZ-444 rear CVDs. Custon CVD's can also be made easily by cutting the length and brazing together, or even using boat shaft adapters to hold the two ends together after cutting. It's a DIY car after all. Being able to make and adapt parts like this is a valuable skill in the model world.

Thanks. The only real weaknesses of the design is the low temperature resistance of printed plastics. The diffs, motor mounting plante and slipper can overheat and deform when printed from PLA. I'm hoping a new wonder material comes around soon that has the stiffness and ease of printing of PLA and the heat resistance of ABS.

Update: I have ordered some cheap steel diffs and CVD shafts from Banggood which I will try to see if I can integrate into the design as an option.

this is the only r/c car that has true racing performance that I have seen on any 3d printing site. I think you might be wrong about your saying that you don't think you could make a better car then the big boys ( Losi *TLR Racing, Associated, Etc...). I raced for Mugen Seiki and Airtronics about 5 years ago is when other things took my focus out of racing. But given that I haven't built the Lynx, but thought it was a very well 3d Printed buggy for all intensive purposes, if this one is as much better as it looks to be, it could very easy be converted from just a 3d Printed buggy to a injection molded and aluminum or carbon chassis. I believe you have a very very good base product to which you can make yourself and some other people an amazing vehicle for racing, maybe not at a World Championship level just yet, but I do believe that with a couple of pro or even am drivers this thing could be turned into an every weekend winner at all levels. I am broke from the holidays but plan on getting this so I can have a look at it. I also have all the other companies last gen and am starting to get the files from them on the current generations, and would love to see where this matches up with them. Based on the pictures it looks like it is a much better layout then the 22-4 and the B44. But I will have to compare files to see where it can be potentially helped. If you are interested in getting any kind of feedback from a random stranger, I am more then happy to show you what I think could make it better if its at all possible, keep in mind I haven't yet gotten the files from here yet. Thank You for posting this up here for sell and I hope you are getting as much business as I feel you should. Posting the last buggy for free was awesome too. I thank you for that as well. It seems that the making community for the most part doesn't thank the creators enough, especially the ones who are working countless hours to make something and give away source files for free, but the same people will post the pictures of them making the projects next to a handful of Redbull's and Starbucks, but couldn't even tip the designer. So thank you for your contribution

Thanks for the inspiration! I’m on the verge to print my own RC Buggy, BUT...

I have a very fast LRP S10 Blast, but it is heavy and constantly breaks - it is driving me nuts. What I could replace by aluminum I have done, but even the short metal axes snap. And the last damage was that the rear end broke off as the rear diff split in half. The thing is too powerful and jumps too far ;) On top of that, the model is very outdated and sources of supply are drying up.

After looking at many RC car designs and video's I think that a light RC Buggy might be the way to go and that it could possibly survive big jumps and rolls, but I’m not alone on the track. I cannot imagine that this/your great design would live when a 1/10 Traxxas is hitting you or lands on top after a big jump.
How do you see this? can your design (or basically any 3D printed RC car) withstand the rough environment of racing & jumping & banging on the track?

Again, thanks for your work and I’m looking forward to your insight!

Would you like to support Cults?

You like Cults and you want to help us continue the adventure independently? Please note that we are a small team of 3 people, therefore it is very simple to support us to maintain the activity and create future developments. Here are 4 solutions accessible to all:

  • ADVERTISING: Disable your AdBlock banner blocker and click on our banner ads.

  • AFFILIATION: Make your purchases online by clicking on our affiliate links here Amazon or Aliexpress.

  • DONATE: If you want, you can make a donation via PayPal here.

  • WORD OF MOUTH: Invite your friends to come, discover the platform and the magnificent 3D files shared by the community!