RC4WDs New Micro Crawler

[Aeronuclear]

Hi all,

I have been trying the double motor set up, only half way through. but I am stuck on the drive shaft pin. The motor fit nicely but I can't figure out how to fixed the shaft of the reduction motor to the drive shaft. Tried drilling a hole in the motor shaft but it's damn hard. Broke my drill bit with only a shallow hole.


Any idea guys? Thanks

Sorry double post. And I can't seems to be able to attach photo

[Aeronuclear]

Found some suitable size screws to grip the drive shaft now.. All is good plenty of torque as I am connecting the two motors in parallel. But as soon as I turn the steering the two front wheels become jerky and stop the truck. As soon as the steering is straight then all smooth again.

I am not electrician but does it means there is not enough current? This is on stock ESC.

Will try connecting in series later and see what happens...

[Shape_Shifter]

Originally Posted by Aeronuclear

Found some suitable size screws to grip the drive shaft now.. All is good plenty of torque as I am connecting the two motors in parallel. But as soon as I turn the steering the two front wheels become jerky and stop the truck. As soon as the steering is straight then all smooth again.

I am not electrician but does it means there is not enough current? This is on stock ESC.

Will try connecting in series later and see what happens...

Yes, your servo is sucking too much current. It may be binding, or over travelling, or just suck in general. You may need a BEC.

[Aeronuclear]

Originally Posted by shape_shifter

yes, your servo is sucking too much current. It may be binding, or over travelling, or just suck in general. You may need a bec.

bec?

[Shape_Shifter]

Just try to adjust your steering end points first. If your transmitter does not have that function, you can do it mechanically with the servo horn. Just make sure the servo isn't binding or pushing against the natural limit of the axles' steering travel.

You'll have to research what a BEC is in the world of RC vehicles. Almost all ESCs (Electronic Speed Control) have a built in BEC (from the ancient Tamiya Language; Battery Eliminator Circuit) which takes the higher voltage from your main power battery and regulates it to a lower voltage that your radio equipment needs - thus eliminating a need for a separate battery pack for the radio/servos.

We would need to see (clear) pictures of how you have everything wired to be any more help.

[Aeronuclear]

Originally Posted by Shape_Shifter

Just try to adjust your steering end points first. If your transmitter does not have that function, you can do it mechanically with the servo horn. Just make sure the servo isn't binding or pushing against the natural limit of the axles' steering travel.

You'll have to research what a BEC is in the world of RC vehicles. Almost all ESCs (Electronic Speed Control) have a built in BEC (from the ancient Tamiya Language; Battery Eliminator Circuit) which takes the higher voltage from your main power battery and regulates it to a lower voltage that your radio equipment needs - thus eliminating a need for a separate battery pack for the radio/servos.

We would need to see (clear) pictures of how you have everything wired to be any more help.

You are spot on, if I turn down the steering trim to about 50%, everything went smoothly. I can't seems to attach photo, haven't got the option, maybe I am new here, less than certain number of post? I am connecting ESC positive to first motor positive then to second motor negative and so on.

I am inclined to rule out binding as everything was fine at full lock when using 1 motor. Physically I can't see any obvious touching.

Does the ampere increases as you increase the steering angle?

[Shape_Shifter]

Originally Posted by Aeronuclear

You are spot on, if I turn down the steering trim to about 50%, everything went smoothly. I can't seems to attach photo, haven't got the option, maybe I am new here, less than certain number of post? I am connecting ESC positive to first motor positive then to second motor negative and so on.

I am inclined to rule out binding as everything was fine at full lock when using 1 motor. Physically I can't see any obvious touching.

Does the ampere increases as you increase the steering angle?

Amps will increase as anything binds. This means the servo and/or one or both of the drive motors.

Im confused - did the steering travel adjustment fix it for you or not?


Edit: with two motors , you probably need an external BEC.

[Aeronuclear]

Originally Posted by Shape_Shifter

Amps will increase as anything binds. This means the servo and/or one or both of the drive motors.

Im confused - did the steering travel adjustment fix it for you or not?


Edit: with two motors , you probably need an external BEC.

The steering travel did fixed it but I have 50% less angle. Looking closer, if I increase the steering angle to full again, when moving, the whole front end (axle, side links, and drive shaft) is jerking up and down. Sounds like a 'mechanical' problem. The rotating motion from the drive shaft seems to be causing it, the more I turn the steering the worse the jerking.

[Aeronuclear]

I managed to mount an N20 gear reduction motor on to the rc4wd original gearbox, with a bit of minor mod. I still can't post picture but will try and explain in words.

Basically, I filed down the 3mm shaft from an N20 200rpm motor to take the original rc4wd pinion, which has a 1.5mm shaft hole. This bit is not easy and my filed down shaft definitely does not look pretty, but it does the job. Then I made the two original holes on the gearbox fixing to the rc4wd motor wider/more elongated, allowing me to fix the existing holes of the N20 onto the gearbox. For comparison, the holes on the original rc4wd motor are 11mm apart, and those on the N20 motor are 9.5mm apart.

Results, well the downside is it is very slow, proper crawler speed, but, the torque is amazing. I can climb all sort of things in the house and garden. But very very slow.

Before this I tried the double motor set up but didn't like it. Connecting in series, the power is low. Connecting in parallel, the torque is good but too fast to control.

Sorry the bottom of this page says I can't post attachment. Would like to share some photos otherwise.

So all things can be put back to original but the gearbox holes holding the motor will be wider/more elongated, which is a one way ticket.

I managed to put some photos up in another discussion:

http://www.scale4x4rc.org/forums/sho...15#post1045915

It's the post posted at 4:13pm by aeroelastic

[Aeronuclear]

Some videos on the tube with my N20 reduction motor:

Bill if you are here, yes I bought this from you and modded it... Videos are for sharing, Hope you are cool.

This first one was taken by my little boy so...

https://m.youtube.com/watch?v=jn-GVowxC64

Next two climbing up and down steep ledge:


https://m.youtube.com/watch?v=TvTQPAL82Aw

https://m.youtube.com/watch?v=SztLOeiZAmU

Last one, indoor reversing up steep board, can't go forward as it will flip over (centre if gravity). Note the drag brake from the motor, enough to hold the truck:

https://m.youtube.com/watch?v=F33yT7f1gFw

[Brake Weight]

With it geared that low, you can see/hear the slack getting taken up in the drivetrain.

[Sparks1337]

Sweet

Can you give some more detail on filing that shaft? I thought about doing this but couldn't figure how to cope with the flat - I was worried I'd end up with an off-centre result.

Since you've proved it is possible there is no reason not to try this with a bigger gearmotor, and experiment with different ratios. The N20 is tiny and a bigger can would allow a higher ratio box/higher wheelspeed with just as much or more torque. I suppose you'd lose some of that fine control though.

Identical - looking but 16GA (losi size) motor/gearheads are plentiful on ebay as well as longer can HBX type ones - the highest ratio I've seen is 300rpm. I went hunting for 130/180 size ones but can only find them by the 1000 on alibaba

[Aeronuclear]

Originally Posted by Sparks1337

Sweet

Can you give some more detail on filing that shaft? I thought about doing this but couldn't figure how to cope with the flat - I was worried I'd end up with an off-centre result.

Since you've proved it is possible there is no reason not to try this with a bigger gearmotor, and experiment with different ratios. The N20 is tiny and a bigger can would allow a higher ratio box/higher wheelspeed with just as much or more torque. I suppose you'd lose some of that fine control though.

Identical - looking but 16GA (losi size) motor/gearheads are plentiful on ebay as well as longer can HBX type ones - the highest ratio I've seen is 300rpm. I went hunting for 130/180 size ones but can only find them by the 1000 on alibaba

It took me like 2 hours to filed it down, with my wife sitting next to me laughing away, so got a bit determined.

I started filing the non flat bit of the shaft, just with normal hand chisel, with the original motor next to me, comparing them now and again to make sure that I don't overfiled it. While it's about the size I want, I connected the motor up with a 6v supply from my old mini z and start fine tuning i.e. Run the motor shaft and work out where to rub to give the best trueness. Try at own risk..

To be honest, mine ended up a bit off centre too but it works...

The original pinion is 10T with 0.3M pitch. About 4.5mm overall diameter. 1.5mm hole in the middle. So if some one can find a 3mm hole one with similar pitch it will bolt right on the N20. But I doubt if this motor exists, with 3mm shaft you have almost no more space for gear teeth for a 4.5mm overall diameter.

Although it drives very slow, I like the fine control and I can crawl on a lot of things Indoor. Even my little boy find it easy to control.

The N20 fit just into the original space, but I have to reverse one of the link bolts to clear the rear end of the motor.

Putting the whole gearbox back in is tricky, as it is a tight fit. I ended up removing the rear steel bumper to release things a bit to fit the gearbox bolts in.

I am looking at crawler tyres now, I like the softness of the stock tyres but the thread are not rough enough to pull the truck up small vertical ledge. The closest rc4wd tyres I can find here in the UK are the Interco swamper, anyone tried these before? The rest of them are from the States or China, which take ages to arrive. I like the Rok Lox but again not available in the UK...

[Sparks1337]

Cool thanks for sharing. That's some dedication! The swampers are great - same dia as the stock grabbers but a lot more bite. I'm running them on mine - if you cut all the smaller lugs off they're even better

Sent from my GT-I8190N using Tapatalk

[Aeronuclear]

Originally Posted by Sparks1337

Cool thanks for sharing. That's some dedication! The swampers are great - same dia as the stock grabbers but a lot more bite. I'm running them on mine - if you cut all the smaller lugs off they're even better

Sent from my GT-I8190N using Tapatalk

Thanks..

You have any photos of the swampers on the truck?

[Sparks1337]

Originally Posted by Aeronuclear

Thanks..

You have any photos of the swampers on the truck?

I do, and I'll take any excuse to whore them around ;)

[Clingman]

Those look great. The blue is a nice choice, too.

[Aeronuclear]

Very nice truck you have there!

Does the front tyre rub the fender at full steering turn? As they are slightly wider than stock.

Are you using full foam in the tyre?

[Sparks1337]

Thanks lads Using full foams and they do rub a bit at the front. Thought I'd need to trim the arches but it is more the inner arch where they rub and they don't catch, so I'm happy enough.

Rok lox are also a good choice. Worth the wait from china for a more scale look and they have decent bite. Smaller diameter means the pumpkins drag more tho

Sent from my GT-I8190N using Tapatalk

[chevy55]

29:1 gru with a 70t 130 can. Plenty of power now.



2s test run:

https://youtu.be/Z05PTb7GGAI