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DIY RC Street Racing Car: One Week Classroom Project

by Banana_Science Feb 13, 2018
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If it is not too much trouble could anyone who has finished the project list how many of each nut, locknut and bolt is needed for this project?

Awesome! An additional question though: I'm looking at the Car Base Assembly, Standard RC Car Package and Deluxe RC Car Package blocks of information that all have different quantities of hardware in them and I don't quite understand the logic. Which of those applies if I'm following the "build guide" here on Thingiverse?

Ah sorry for the confusion. A lot of that data was put together and never used so I cleaned up the spreadsheet and this is all you'll need https://docs.google.com/spreadsheets/d/1UG9TA4e-daesGxKVQh-D9R9EstoqKRO_E86S95O0Opo/edit#gid=1458453795

Top secret information: we are working on a modified version 2 of this car which will be released in a couple of weeks if you can wait. You can see the in-progress designs here: https://cad.onshape.com/documents/5903c81732c76410354ded00/w/c32ba6e82f677c2851edf4c7/e/bede4aba97534eab18edd6ec

Basically it greatly improves:
-Simplicity and weight by eliminating unnecessary hardware
-Integrated wheel suspension system improves traction and performance across rough terrain
-Strengthened steering mechanism and bumpers protect against crashes better
-Autonomous capability (a lot more details on this part on the way but not for a while)

Thank you for the clarification and the link to the parts list for v1. One thing I noticed was that the in the summary under Thing Details M5x40 bolts are listed as necessary hardware for assembling the front axles but the parts list has M5x35 bolts instead - what is the correct spec or doesn't it matter?

As for the v2 it is great to hear that development is ongoing on what is already a very cool project in my opinion and since parts from China will take some time to arrive anyway I will most likely build the new version when all the details about it come out. Are you planning on creating a separate listing for v2 here on Thingiverse or modifying the v1 page? Also checking out the v2 Onshape document it seems that all the same non-printed components can be used besides the nuts and bolts - is that correct? Finally you have here in the comments indicated that the 7200kV motor is a bit overpowered and since a 5800kV version of the same motor listed in the project is also available would that be a better option?

M5x35 bolts will work for V1 but you will need M5x40 I believe for V2. We do plan to create a new listing since there's gonna be a lot more details with the autonomous "module" we are going to add on. All of the parts from V2 are actually compatible with V1 bottom plate. The only difference regarding the nuts and bolts hardware on the V2 is instead of countersinking M3 lock nuts into every 3D printed component, we use knurled insert nuts (insert by heating and pressing in with soldering iron) which make assembly and disassembly easier and everything overall stronger. I would go for a lower KV for improved low throttle control since the 7200kv is a little too overpowered.

Here's the type of knurled insert nuts we are talking about: https://rover.ebay.com/rover/1/711-53200-19255-0/1?mpre=https%3A%2F%2Fwww.ebay.com%2Fitm%2F20PCS-M3-x-4MMX5MM-female-threaded-knurled-brass-insert-embedded-nuts-M3P6%2F253374298838%3Fepid%3D9012565978%26hash%3Ditem3afe48fad6%3Ag%3A2GAAAOSwbWZaXqqM&campid=5337956198&toolid=20008

Alright thanks for all the info once again, hopefully there are no showstoppers and you can release the v2 shortly.

Yup. We just finished designing a first prototype and will begin testing this weekend

can i use 2s 18650 battery in this project

I'm struggle with the gearing, the motor just stutters. The motor can run free when there is no gear on the shaft or when i have the car in my hand. I build two of this cars and both of them have the same issue, so they are both non driveable. It's is like when the motor have to get soms ressistance, it just begins to stutter instead of driving. Do you have some suggestions? (i uses several gearing from PLa to all metal now)

Sounds like a motor torque issue of some sort. Can you easily turn the rear wheel with the motor installed? What motor and battery are you using?

Hello everyone, I have some problems with the gears. Does anyone have an example which one, besides the one from HobbyKing, works? or which module do the 3D gears have?

Sorry for the late reply! The gear has a module of 1.25 and can be easily customized (if necessary) from our public Onshape document simply by changing one number then pressing export. As an alternative to the HobbyKing pinion gear, I've heard others have been successful with this one. I hope this helps and please don't hesitate if you have any more questions!

Thanks a lot for your answer. I am going to try the one you suggested!

I have a question concerning the tyres: if I am not mistaken, the front tyres are bigger / higher than the rear ones. Is there a reason for this?

Hmmm... the front and rear tires should be the same diameter but the rear tires should be wider to increase traction.

thanks for your quick respond !I am going to check it again!

Hey, I've printed the model out and it looks AMAZING, but I was wondering if you had any .stl of a cover for the top to make it look cleaner?

Yup, this will make it more looks like a car. Regardless i'm not a designer....

I just have an .STL for upper plate but sadly no full cover. If you like though, you could easily design one by simply making a copy of our [public Onshape document] (https://cad.onshape.com/documents/5903c81732c76410354ded00/w/c32ba6e82f677c2851edf4c7/e/467fdf2a13bda55d8d40fc77)

Some quick notes on my build to share with the community...

I tried printing the bottom base plate on my 3D printer, but its a bit warped. Laser cutter is still on my wish list, so I had Ponoko laser cut a couple it in the mean time.
(They are good folks, so I'm happy to give them the business.)

Placed three orders with them, one has come in... great price, just plan on 2-4 weeks for parts to arrive. (I thought they'd be a little quicker.)

I'm experimenting with the infill on some of the parts. I figure the front wheels will be under less stress, so I printed them with three passes on the circumference, and then 20% hexagonal infill. They are very soft and still seem really strong. (I'll let you know how they do... perhaps they will wear out quickly.) Printing rear wheels at 60%.

Still just a pile of parts at this point, more soon...

Lovely project! It is on my shortlist (things to print). I already ordered the motor/esc, pinion etc... But as the metal pinion i would like to use a metal gear also, but all the metal gears i found, the have a round heart. Do you have any recommendations regarding a metal gear?

Thanks! I've only ever used plastic 3D printed gears with this project which have held up surprisingly well so I'm not sure what metal gear would work best. If you do find a metal gear though, you could possibly print a very tight insert to convert the center axle hole into a hex hole that would fit over the rear axle nut. I'm sorry I can't help you more but if you ever do find a good metal gear, would you be able to send me a link so I can include it in the post for others with the same question? Thanks again!

I just ordered this aluminium gear (80 and 85 T): https://www.aliexpress.com/item/1pc-J167-80-85T-Delicate-Aluminum-Alloy-Gear-0-5-module-for-DIY-Model-Making-Free/32755347956.html?spm=a2g0s.8937460.0.0.1d9a2e0e5aG59F
I will 3d print a conversion nut for it when i have all the components and will share it here.

cool i ordered one too :)

Building this over holiday break... but the battery is out of stock. Any recommendations on an alternate? Not sure which specs can vary... (not voltage or 2C, but...)

Also, and recommendations on a good charger?

Capacity (Milli Amp Hour) can vary (larger mah rating = larger capacity = larger physical size). C refers to the rate at which the battery can be discharged. To get the discharge rate, take the C rating then multiply it by 100th the mah rating to get the maximum constant amps (eg: .550(550mah/100)x75c = 41.25a capable discharge). Since this RC car doesn't require extreme power from the battery, any battery 25c or above should work fine. The one thing you really don't want to change is the battery cell count. LiPo batteries are made of multiple cells wired in series to add their voltages together. You need to use a 2 cell battery for this car as the motor won't turn on one cell and may catch fire on three cells. Here's a good battery that's in stock: https://www.banggood.com/custlink/3mDK37Qs7n In terms of charging, to keep things simple and cheap, I would just get a charger like this one: https://www.banggood.com/custlink/GK3v3fbbf2

Hope this helps and let me know if you have any other questions!

Other question : in witch position did you print the side guard air intake??

If I remember correctly, I think I did it vertically.

indeed, it worked well :) thx

Do you think this pinion can do the trick?
ABWE Meilleur Vente 2 Pcs 48DP 3.175mm 14 T Moteur Pignon pour RC Voiture Brossé Moteur Brushless

Hmmmm... I would give it a shot for only $2. Seems like it might work but I can't tell for sure. I'm no professional when it comes to gears.

Hou hou hou!!! Thank you so much! i'll give a try :)

Well, I didn’t start the assembly yet but here is some pics of the 14t pignon gear on Ali I ordered https://s.click.aliexpress.com/e/cHiuQe9a

1/it is a little bit loose on the motor but since there is a screw to secure it, it should be fine. I hope... I have to source the screw btw.

2/I tried to print a gear included (61t if I remember correctly) but it doesn’t match well. I think more teeth will be good—like 80—and may match with the pignon gear.
However, I ordered a metal one on Ali too cause I think it is complicated to print one with a good accuracy plus plastic vs high torque metal I’m skeptical...
If the combo work I’ll notify everyone. :)

Could I size files down to 1/32 rc scale for a micro car ?

Coud I size files down to 1/32 sacle for a micro car ?

That might work but the fittings might be a bit small as the tolerances are for the current scale.

Can you tell me what scale this rc car is, if I want to buy the axles , wheels and tires ?

It wasn't designed to be a specific scale but I would try 1/10.

Thank you for this thing! Thumbs up to you!

  • Posted with 3D Geeks Thingiverse Browser App

Finally my "DIY RC Street Racing Car" project is done and the car is working as showed in the video. I had problem to source the 14T 2mm Pinion Gear from hobbyking.com. Printing it from the STL model (found in the forum here) lead to gear a meld down disaster. I finally found a solution with following parts:

  • 14T 2mm Pinion Gear: "Wltoys L959 RC Car Spare Parts Motor Gear 14T L959-34"
  • 61T gear from "51004 Tamiya TT01 G-Parts"

I had to drill a 2mm hole into the rear axle to fix the gear with a bolt.

Comments deleted.

For people who have issues with the printed pinion gear (I could not make mine stick to the small 2mm shaft) and as Hobbyking one is out of stock - I found https://www.amazon.com/gp/product/B00A29ACPW/ref=od_aui_detailpages00?ie=UTF8&psc=1 and it works nicely.

Nice! I'm sure that'll help a lot of people! Thanks!

Comments deleted.

Thank you for this thing! Thumbs up to you!

  • Posted with 3D Geeks Thingiverse Browser App

Thanks for supporting us!

I noticed the rear driven gear would strip after even one run - motor torque on the drive gear is awesome.

You will have to do some scaling of the driven gear to ensure good meshing. Another option is to make the upper motor mounting hole a slot so gear engagement can be adjusted.
I scaled up my gear 103.5% and got good engagement, but the length of the gear was less than the length of the drive gear. Since there was room, I first beefed up the gear by making it wider so that in all cases it would mesh with the drive gear. That helped, but that instant torque could strip the gear in seconds.
So I played around, and I ended up with a 3-piece design. I wanted to absorb the torque shock on the teeth so I could run it for more than a couple of minutes!
I made a three piece unit - center hub in PETG or PLA, outer gear in PETG or PLA, and the body of the gear in PU Flex. Seems to hold up much better.
I have a dual head printer and printed all at once, but it does not turn out as well as printing the items separate and pressing together. Also, if the outer gear is damaged or stripped, simply pop off the old one and press on a spare - see pic of the first one made - a little rough but works.

Hmmm... what pinion gear are you using? Some other pinion gears with the same 2mm 14t spec can be a different diameter and cause the rear drive gear to strip easily. We've designed this car around the pinion gear linked in the description so that we've never had to replace a rear drive gear at all. If you want, you can easily change the tooth count, diameter, and more of our rear drive gear to make it fit better by simply changing a few variables in our public Onshape document. Nice job coming up with that nifty fix though ;) Hope this helps!

I ordered the pinion on the list. Regardless, the gear tooth size is small enough that .1-.2 mm variation in center to center distance (3d printer variance) would reduce engagement. My first gear stripped before the car traveled one foot; this prompted me to look closer.

Just sayin’. Some adjustment might help some builders. I noticed you mentioned having extra gears printed for the class since they do wear out after a while.

This project has been fun!

That's good to know! Thanks for the advice. We have just uploaded 6 other gears of slightly differing tooth counts to make it fit better for different printer tolerances.

Makes sense. Change the tooth count and change the pitch circle.

Do you have better durability with the PLA or PETG.

I haven't tried PETG yet but I've been running the same PLA gear for the past four months (like 50 batteries). PETG is definitely worth a try though.

Hi. This thing looks frickin amazing! I need to give my dad a list of the parts and the prices so I was wondering what the quantity of the non printed parts. Are they all one each?

Thanks! For most of the non 3D printed parts besides the bolts and nuts, you only need one.

I'm having trouble sourcing some of these parts in Canada. The one motor I found was this: https://www.amazon.ca/abcGoodefg-Brushless-Accessories-Quadcopter-Helicopter/dp/B07D546LXK/ref=sr_1_3?ie=UTF8&qid=1533097136&sr=8-3&keywords=rc+motor+with+esc

Would this work? I've also had a hard time finding the pinion gear in Canada, are there any alternatives?

Hey, sorry for my late response, I read your message and forgot to respond. I don't think that motor will work unless you do some gnarly modifications. I would get this motor instead. The key thing is to get a 2430 7200KV 4P brushles motor since that is the motor the car was designed to fit. I'm not sure what parts are available or not in Canada so I'm not sure how much of a help I could be in that regard. If you have a question whether or not a part will work or not, feel free to contact me and check though. A lot of other people are also having trouble sourcing the pinion gear since they seem to be out of stock but I think another Thingiverse user designed a 3D printable pinion gear and posted their .STL in the comments here somewhere...

Comments deleted.

Thanks so much for this project... I love that is has both CNC and 3D printed parts. I have the car built and for the most part working and have learned a ton along the way. I am having an issue with the pinion gear and the drive gear that I was hoping to get some advice and/or a suggestion on how to fix. The pinion gear and drive gear don't touch. To make contact I put a shim in to pivot the pinion gear toward the drive gear, which works but tears up the main gear. I am wondering if I purchased the wrong pinion gear (https://www.amazon.com/gp/product/B000BQ5AYY/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1) or if this issue has been seen by others? I feel my options would be to make a slightly larger main gear or try to drill out the mounting holes and move the motor back towards the drive gear. Is the source file for the main gear available for me to make modifications? Also if I opted to drill out the mounting holes will the screws be able to hold the motor in place, or will they most likely slip?

Again, great project!

Yeah it looks like you might be running the wrong size of pinion gear. I would get the one from Hobbyking when they come back in stock as that was the one we designed the car around. If you want to make some super easy changes to the 3D printed gear to make it fit your current pinion gear, just change the tooth count variable in the gear part studio within our Onshape document and everything should reconfigure itself. I would not recommend moving the motor or jerry rigging any motor mounting solution because even the slightest bit of slip on either gear will cause them to totally shred into nothingness. Just change the tooth count and print a slightly larger rear gear.

We also happen to have a crap ton of motors, pinion gears, and ESCs left over from the 2017 Inventing Reality Summer Program which we would be happy to ship to you if they would be of any use. You just gotta pay postage. We just have no need for 12 extra cars ;)

Hi there, I would love to get some of these parts from you if you have some available still. Having a hard time finding the pinion gear and motor in Canada.

I got the wrong pinion gear as well, so I would definitely pay postage as well as be willing to make a donation to your program for future projects you do if you're willing to send some parts! I will send you a direct message regarding this.

However, I also wanted to confirm the STL for the bottom plate that's posted is the updated version for 3d printing, correct? I wanted to print a new one with correctly sized holes.

Yup the STL labeled for 3D printing can be printed with the slightly larger holes.

Thank you for this thing! Thumbs up to you!

You're welcome!

I've finished printing everything in resin, thought you might be interested in a picture of all the parts pre-assembly. They still need a small amount of sanding to get rid of some of the bumps left over from supports, but they're ready otherwise.


There are so many design flaws with this. There are no assembly instructions, so I had to just figure it out on my own. The sides don't fit properly into the baseplate, so I had to drill the holes to make them bigger. And when I finally finished building it, it stoped working after about 15 seconds. The smaller gear was so stripped and utterly destroyed that you couldn't even tell what it was supposed to be anymore. The only reason I'm still trying with this is that it still looks like a lot of fun to drive.

Sorry to hear that! Did you 3D print the bottom plate? It's sized so that it needs to be laser cut or the fittings will be very tight. I'll work on a 3D printed version tonight to fix that though. I'm not sure what happened with the rear gear though. I would check that everything is tight and you are using the right size pinion gear. If even one of the motor screws are lose, the rear gear will grind down quickly. I've owned my version of this car for over six months and have only had to replace the steering servo a few times after hard crashes. Additionally, we guided almost 20 6-12 graders to build these thing last summer and never had any problems with the fittings or gears over the course of the week. What filament are you printing with? The tolerances on this car are such that it's ideal to print in PLA.

I 3D printed the bottom plate. I did figure out the problem with the gear though. It was on but not quite all the way, so it was only barely touching the other gear. Guess I'll just have to shove it on harder. Yes, I am using PLA. I guess I was just a little irritated when I posted that, but now I've calmed down and fixed most of the problems. To be honest, it was a little fun figuring out how to build the car on my own instead of using instructions.

One other question though. How long is the battery supposed to last? Should I charge it after every use, or just once in a while?

XD Glad it worked out. I know how frustrating a poorly put together tutorial can be especially after you spent $65 on parts! Really sorry about that. Hopefully my updated bottom plate should help. Sorry for not thinking of that earlier and uploading a modified design for 3D printing. With an 850mah 2s it should drive for like 15-20 minutes of continuous driving based on my very limited testing. I would charge it every time...

Okay so I just updated the bottom plate so that it should fit when 3D printed without having to drill out any holes. I hope this helps!

Oh no! I had just finished 3d printing the bottom plate in tough resin! I hope I can easily fix the holes

nooooooooooooooooo!! Resin is so expensive as well! Sorry about that!

I'm going to try to still use the one I already printed since it looks really nice - What modifications need to be made? Do the holes just need to be a little wider?

All you will have to do is drill out a few of the holes. The holes should only be .5mm too small so you might just be able to self-tap the screws in and avoid drilling all together.

This is awesome, thanks for posting this. My daughter and I have been going through the onshape tutorials to design the parts there are tutorials for and we've started printing and almost have everything printed, so we'll start building soon. I think I didn't print enough of some of the pre-designed smaller parts, though. There's the list in the main details of the 3d printed parts, but I don't see a quantity of how many you need for some of them. Is there a consolidated list somewhere?

I also took a slightly different approach and have only printed one part in PLA (the ruler). Everything else has been printed in a form2 SLA printer in durable, tough, and flexible resins.

Wow! It’s good to see somebody using our tutorials again! Sorry for not including the quantity of parts required I’ll add hat in tonight when I get back home. It’s going to look super clean after being printed on a Form2 compared to just an FDM.

Thanks, I appreciate it! I also saw a tutorial in the folder for the micro quad copter - we were going to try that next! I was new to OnShape and my daughter is pretty young, so it was a learning curve, but she got the hang of it. She enjoys TinkerCAD a bit more since it's easier and colorful. I saw some of the items in the "Project Ideas" for TinkerCAD in your Drive share, but didn't see associated tutorials like the OnShape ones. If you have any and willing to share, I'd love to see them. Thanks for sharing those, they are great!

We have three other projects we taught at the Inventing Reality camp including: brushed micro quadcopters, fully 3D printed model rockets, and compressed air marshmallow blasters. We’ve been really busy recently but will try to make an effort to list the remaining three projects on Thingiverse ASAP. I’m not sure if we also shared our tinkercad slide decks as well but we also have a few tutorials on the basics of tinkercad as well. Thanks!!!!!!!!

Hi there. Any chance you could help us with the wiring the jst connector to battery. I have built the car but no idea what wires to cut to plug into other wires. I cant see any details in your photos. Any help here would be appreciated. Thanks

Sure! Sorry for not including any wiring photos. Here's a photo of how all the wiring should look outside the car. Just let us know if you need any more details!

How do you power the receiver? from the ESC? or you need a connection to the battery?

Actually scrap that last comment. I figured it out. I bought the battery from amazon and it came with a XT30 plug so I need to get an XT30 female for the ESC I believe.

Yup an xt30 would work great

That helps us a lot thank you. The battery in the photo looks different to the one you link to. Is the photo above a T connector connected to the ESC, because that's what connector comes with the battery already. In your instructions you say to change it for a JST socket. I'm still a little confused. So I potentially need to buy a T connector for the ESC not a JST connector perhaps ?

Sorry I just haven't converted those connectors yet in the photo. That battery in the photo is also not the correct battery. I just used it in the photo because I couldn't find the correct one ;)

The total cost of non 3D printed parts including everything such as bolts, nuts, and connectors is $62.74.

Ok thanks for the reply , and awesome job you and your students did :)

Comments deleted.

hey , will the engine mount except any other type of motor (size) ? Ty

I'm not sure. I've only tried one size but it would be relatively easy to update the design to fit a different motor.


What temp settings did you use for the printing of the Ninja flex ?

Whats the total cost of all the non 3d printed parts and about how many printing hours does it take?

The cost of non 3D printed parts including everything such as bolts, nuts, and connectors is $62.74. I never thought to time the printing but if you were to do the hybrid TPU/PLA wheels it would probably be around 50 hours

Very simple design and well explained in words and pictures. I am trying to learn how to build something like this and your post helps a lot. Thank you.

Why didnt you pick the GT2B remote. That one has work really well for small projects like this. Especially for electric skateboards. It's cheaper too. Just wondering?

This remote just happened to be a little cheaper I guess.

Awesome, i wonder if a lower KV motor may be better looking at the traction and speed.

Comments deleted.

Definitely. The car suffers from an overpowered motor and poor traction due to its light weight. It works really well on old, roughed up asphalt though with the current setup.

Can you please comment on both front and rear axles how many nuts, where they are located and what type? I think i've figured out the rear axle but just want to check. Trying to figure out front now.


Sorry about not making it more clear. Here are some screenshots from our Onshape design. If these screenshots aren't enough, you can easily copy our document and orbit/pan/delete parts of it to see how it all fits together. Just let us know if you want an exploded image of the rear axle.

Awesome, thanks!! My bearings should be arriving today so i'll be able to assemble the car! I'll post some pictures when i'm finished!

Do you have any video for it? Looking forward to make it with my grand kids. Thank you for sharing.

I just finished a quick driving video: https://youtu.be/rkeiZ0WCqgk Sorry it took so long (lots of homework)!

Looking good. I made 2 of them already. The only difference from your original build:

  1. 3D printed all parts (no laser cut).
  2. Motor pinion gear is out of stock, made 3D printed with set screw- working great, can provide .STL file if needed.

Can you post pinion gear stl??
Thanks :)

Awesome, Thanks!! What size set screw did you use?

i used 3mm x 5mm regular screw

Thanks for that file! Mind if I upload it this listing and credit you in the description?

No problem at all.

Wow! A 3D printed pinion gear! If you could post an .STL that would be great! I know those gears are always out of stock and it would help a TON of people if they could just print their own. I'm glad you like the design!

I don't have an official video yet, but I'll film a quick something this afternoon for you.

Great, Thank you! I started printing plastic parts. Will post some pictures when it done.

Sorry, but I ran out of time this weekend. I'll try my best to get something quick filmed ASAP.