Jurgen Krooshoop

Small Yellow RC-car

17 posts in this topic

For the instructions scoll to the bottom of the post

Hello !!

Ever since I took part in

races at the latest Lowlug meeting,

I've become addicted to racing with self-made LEGO-racecars. First I made a very simple RC chassis x2

(which was really ugly), and improvised a race-track in my own attic. There I raced against my brother

until the batteries were completely empty.

So I just had to make small racecars that would also look nice. This is the first in a series of at least 2 small racecars:

The drivetrain is derived from my E.R.T.W.D..

And in contrast to my previous RC car, the Little Devil, it features return-to-centre steering

which makes the car more controllable. It uses the

technic axle connector rectangular triple spring-loaded to return the steering axle to neutral position.

m5117671.jpg

Although it was built as small as possible, I did manage to include quite some features

of which the rotating steering wheel is my favorite. It also has working frontlights and rearlights

m5117675.jpg

The doors can be opened. But they have a small lock, so they won't open during driving.

The trunk opens as well, giving a nice view of the drivetrain.

m5117679.jpg

Since it has to endure some racing-abuse, it was made as strong as possible.

And to protect the front, the bumper was fitted with shock-absorbers.

So driving this thing and crashing into something (which happens regularly) is pretty safe.

m5117681.jpg

The choice of wheels was a consequence of a number of aspects: initially all the wheels

were of the 62.4 x 20 S type, but this resulted in weird-looking cars with wheels that were to big.

So I switched to model team wheels for the front. But I kept the big rear-wheels because smaller wheels

would require more gearing in the drivetrain. Eventually the big wheels give it a powerfull look.

m5117678.jpg

Some technical data:

Lenth: 38 studs

Width: 17 studs

Height: 14 studs

Number of parts: 728 (including the remote controller)

Drivetrain: XL-motor with 3:1 speed increase.

m5117673.jpg

Instructions

I've made complete step-by-step building instructions just as I did for my Little Devil.

The instructions can be downloaded on my website www.jurgenstechniccorner.com

aayellow_racecar.jpg

Hope you enjoy it. Feel free to comment.

Edited by Jurgen Krooshoop

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That is awesome! I love the small RC cars because you can really zip them around.

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Small but furious! The bigger rear wheels sure add a lot to its attitude. Did you think of replacing knob gear for something smoother, like normal gears? Another tip, you might wanna put another beam between motor and gears, so you dont dmage the Xl motor's hole.

Edited by Zblj

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Small but furious! The bigger rear wheels sure add a lot to its attitude. Did you think of replacing knob gear for something smoother, like normal gears? Another tip, you might wanna put another beam between motor and gears, so you doont dmage the Xl motor's hole.

The knob-gear was specifically chosen over bevel-gears and IMO it runs pretty smooth with it. And I don't understand where I should place that extra beam. The XL-motor is already secured with 3 pins on the same side as the output and 2 pins on the side.

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This is an awesome car. I was going to say "little", but it really only seems to be little. I love how fast and how cleanly it drives. The return-to-center steering obviously makes a big difference. This is yet one more model to add to my "must build" list.

Thanks again for making the instructions. I know how much work it is and you did a great job.

Voila!

racecar1small.jpg

racecar2small.jpg

Edited by Blakbird

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@Blakbird:

Wow, your renders look soooooo nice, much better than mine, thanx !!

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@Blakbird:

Wow, your renders look soooooo nice, much better than mine, thanx !!

As long as you keep making cool models, I'll keep rendering them. Seems like a good arrangement to me!

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Cool car + great render = awesome post.

I really like the car, although I'm curious to know how those wheels behave in bends at speed.

Thank you for taking the time to create instructions for your model!

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Cool car + great render = awesome post.

I really like the car, although I'm curious to know how those wheels behave in bends at speed.

Thank you for taking the time to create instructions for your model!

Although the rubber of front wheels is quite stiff/hard, it turns very nicely. The differential and the weight (still approx 700 parts for a relativly small car) give it good driving capabilities. It is quite manouverable, I tested it on my improvized race-track in my attic. Unfortunately my attic is too dark for my camera to make nice footage, which I would have liked to include.

Edited by Jurgen Krooshoop

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Very, very nice. It's great to hear you've also caught the ACC bug, seeing this makes me want to build a new one again :) The huge rear wheels really add attitude to the car.

There's one suggestion I'd like to make to improve the steering; if you replace the 8z gear with 14z gears and place the gear rack directly on the steering beam (removing the jumper plates), your wheels will steer at a much larger angle, improving maneuverability. I've done it right here as well:

sneakerinside3

Edited by mahjqa

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Very, very nice. It's great to hear you've also caught the ACC bug, seeing this makes me want to build a new one again :) The huge rear wheels really add attitude to the car.

There's one suggestion I'd like to make to improve the steering; if you replace the 8z gear with 14z gears and place the gear rack directly on the steering beam (removing the jumper plates), your wheels will steer at a much larger angle, improving maneuverability. I've done it right here as well:

Thankx for the suggestions, I will definately try it. A very good reason to get those old bevel gears out of the box, cause they haven't been used for years, as the newer 12-tooth bevel gears are stronger.

Edit:

OK, I tried the idea, and indeed it improves the steering-lock a bit, but it also causes the return-to-centre to work less good, just as changing the gearing from the motor to the steering-axle does. So it makes it more manouvrable, but more difficult to control.

m5117670_800x600.jpg

Edited by Jurgen Krooshoop

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What could be the problem is the direction of the gears. The gear rack needs to slide on and off the gear, and one direction is smoother than the other. reversing the gears might lower chances of the gears getting stuck on the gear rack.

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What could be the problem is the direction of the gears. The gear rack needs to slide on and off the gear, and one direction is smoother than the other. reversing the gears might lower chances of the gears getting stuck on the gear rack.

You're right, so I reversed the gears, and corrected the wrong orientation of the first gear (which was offset 90 degrees, you can see in the picture). Now the steering works noticably better making the car more controllable.

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Nice model!

And nice of you to provide instructions!

As I see you have created another red car, hope we will see its introduction, too!

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Refering to my other thread about studful and studless construction, this model shows the main advantage of studless b.s., the possibility of including a lot of function in small places, this is a fine example :thumbup: . It's so cool :wub: ...

Edited by Plastic Nurak

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Nice model!

And nice of you to provide instructions!

As I see you have created another red car, hope we will see its introduction, too!

Yes, it will be published ASAP. (I like it even more than this one). I'm working one instructions now, but they won't be ready before the end of next week. Even for a small model like this, it's a lot of work. And after that, a video must be made ... so it will take a bit of time before you'll see it here.

Refering to my other thread about studful and studless construction, this model shows the main advantage of studless b.s., the possibility of including a lot of function in small places, this is a fine example :thumbup: . It's so cool :wub: ...

It would have been practically impossible to make this out of studded Lego. Parts would even come off while racing. I did use a little bit of studded Lego though, and added studs to beams using small pins.

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Awesome RC Car! I'm not into Technic, but seeing this makes me wanna try building one. Great job Jurgen!

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