[WIP] RC (not IR) Racecar

[z3_2drive]

By popping out I mean they come apart under torque. The U-joint is made of 3 pieces and these separate under stress, but you can put them back together. They aren't 'aligned' but there's no room for them to come out that way. As for 8880 suspension It may be a good idea but I am not sure if they are strong enough (the shaft and sphere gear) and very hard to come by in US BL stores...

[AndyCW]

You have to use 8880 wheels, but numerous tires fit on them. His u-joints are failing. The center piece "pops" out of either end. They are staying put because there is slack in them and they can compensate for little differences. v/r Andy

[750ACE]

I wish there was a way to reinforce the u-joint other than strong tape or string; a metal replacement would be great.

[tibivi]

That's right, I had those problems too.

What are you going to do with the weight distribution? 50:50, 45:55?

Are you using RTC steering or caster?

Look forward to pics, keep on building

Tibivi

[z3_2drive]

That's right, I had those problems too.

What are you going to do with the weight distribution? 50:50, 45:55?

Are you using RTC steering or caster?

Look forward to pics, keep on building

Tibivi

weight distribution...well I don't know exact ratios but I tried to get it to have slightly more in the back but not too much or else the front would have no grip. Having slightly more weight in the back ensures it's easy to control but fun to kick out the rear under throttle I'll make some pics and hopefully a video before I start the re-build. The steering is proportional return-to-center as in all hobby RC cars, it works like a dream Edited September 1, 2013 by z3_2drive

[z3_2drive]

UPDATE: I built V2 but I didn't like it at all, so I ordered the old Red U-joints along with 8880 suspension parts from Germany, so the car will go through another re-build. Something I'm thinking of implementing is a swaybar, since a car of this size may need it for better handling, and I know how to implement it. In the meantime here are some pics of the old V1:

[efferman]

how did you control the lego servo with the third party remote?

[z3_2drive]

how did you control the lego servo with the third party remote?

You have to connect it to the motor controller in the correct fashion. We couldnt get it to work at first but then got it right after seeing this:

Then you can switch polarity and adjust it to your liking depending on what Remote/receiver you have.

Edited September 7, 2013 by z3_2drive

[efferman]

thanks ,but you have not automatic return to center or iam wrong?

[z3_2drive]

thanks ,but you have not automatic return to center or iam wrong?

I do have return to center, and proportional

[efferman]

sorry if i dont understand what are you describing, but you have connected the lego servo to a rc speed controller or to a custom controller or simply to the rc receiver like a standard RC servo? more details please

[z3_2drive]

sorry if i dont understand what are you describing, but you have connected the lego servo to a rc speed controller or to a custom controller or simply to the rc receiver like a standard RC servo? more details please

Here is a photo to explain.

The black rectangle is the receiver and the green board is the motor controller. The receiver is connected to the motor controller with two channels. One is for drive and one is for steering. The four wires from the buggy motors connected to channel 1 on the motor controller (wire is coming in from the right) and the servo is connected to channel 2 (black pf cable coming in from the left). The motor controller powers the servo based on commands from the receiver, which receives signal from the transmitter inside the remote.

[efferman]

and the motor controller is interpreting the position control in the lego servo into signals like the potentiometer of a rc servo?

[z3_2drive]

and the motor controller is interpreting the position control in the lego servo into signals like the potentiometer of a rc servo?

yes, which allows for smooth steering

[clarkdef]

Montana is eyeing you up xD

[efferman]

cool! have you designed this controller yourself or is it somewhere to buy?

[Alasdair Ryan]

The electrics look cool,but the chassis seems two long...

[pint14]

I can wait to see the video, but why are the chassis so long?

Edited September 8, 2013 by pint14

[z3_2drive]

The remote is hobby RC standard with 3 channels, two for drive+steer and one for accessories like lights, it is made by the company Futaba and came together with the receiver. The motor controller was bought separate, and is made by a company called Polulu. Yes I noticed the chassis was quite long but if you compare it to a real car the dimensions are relatively normal. V3 may have a slightly shorter wheelbase

[CTgeek]

Hmm. I trying to look at the pics but they don't show. Have you removed them? I'm a bit new around here but have been trying to decide on if I should buy a RC car (because of distance) or see what people are doing with lego (as range on both bluetooth and IR are limited). Thanks!

UPDATE: I built V2 but I didn't like it at all, so I ordered the old Red U-joints along with 8880 suspension parts from Germany, so the car will go through another re-build. Something I'm thinking of implementing is a swaybar, since a car of this size may need it for better handling, and I know how to implement it. In the meantime here are some pics of the old V1:

[pluto7443]

Hmm. I trying to look at the pics but they don't show. Have you removed them? I'm a bit new around here but have been trying to decide on if I should buy a RC car (because of distance) or see what people are doing with lego (as range on both bluetooth and IR are limited). Thanks!

I know, I can't see them either. :(

[Alasdair Ryan]

Brickshelf is down again,the picture are hosted through Brickshelf.

Edited September 13, 2013 by Alasdair Ryan

[Dreadredbeard]

Everytime I see a build with the buggy motors I get sad that they are ~$50/ea in the USA :( I would love to build a 2 speed rock buggy with 4 of them.

[camaudio]

could the electronics fit in a gutted battery box?

[Hrafn]

The remote is hobby RC standard with 3 channels, two for drive+steer and one for accessories like lights, it is made by the company Futaba and came together with the receiver. The motor controller was bought separate, and is made by a company called Polulu. Yes I noticed the chassis was quite long but if you compare it to a real car the dimensions are relatively normal. V3 may have a slightly shorter wheelbase

The wheelbase looks long to me, too. Most cars seem to have a wheelbase approximately equal to 4 wheel diameters; this looks more like 5 or so. But if it's what you want (and if it turns OK!) then it's not an issue.