Motor setups: #of turns and Gearing

[ovstebo]

Hello Yall!

Im reading up on motor setups, but cant seem to find a good answer:

What would be the preferred setup,
1. A high turn motor (eg 50T), no or little gearing.
2. A low turn motor (eg 5.5T), with an ultra low gear, GRU fitted (eg 50:1).

Dont know if any of you have tried alternative #2, as all posts Ive read have featured a high turn motor. In most of my cars, going real slow smoothly is a real problem as they have some sort of "minimum speed". This ruins most of the scale appearance as the speed appears "digital". So Im thinking about fitting a real fast racing motor and a GRU, and would like to know if it has been done (here) before, and what the results were?...

Im thinking on using a CC-01 as a base for this experiment, but I suppose the results will be of a more general nature, thus apply to other "slow" scalers.

What Ive currently ordered are:
1 CC-01
1 Ezrun 5.5T motor with ESC
1 5Ah Li-Po, 2S

My general idea is to fit the motor without GRU first, and measure the speed. The required GRU will then be calculated as a function of its top speed and my desired top speed.

Also, if it doesnt work, Ill use the motor in one of my fast cars"thumbsup"

 

[pantablo]

I run one cc-01 with a 4:1 rc4wd gru on a 55t motor and it has good slow speed control.
Here is video of what that looks like
http://www.youtube.com/watch?v=F0wH8sPPg3o


I run another with a HPI gru, which is 7:1 I think and a 65t motor. Its also good and slow, although the rc4wd unit seems to be better built, smoother and quieter.
Here's that one
http://www.youtube.com/watch?v=sjTSkBoZxYQ

 

[sivad]

I run one cc-01 with a 4:1 rc4wd gru on a 55t motor and it has good slow speed control.

x2 this is my set up to. i love it

 

[gapjr]

A cc01 with a 5.5T :shock:. Video please!!! Hope you've got some spares "thumbsup". Even with the gear reduction that will still be too fast for scale speeds. And...you'll probably tear stuff up....IMHO.

 

[ovstebo]

@ gapjr: Well, this is intended as an experiment, and mind you, Ive seen GRUs at 250:1, which would, if my understandings of what Ive read are correct, be equivalent to a 55T with a 25:1 gearing. That doesnt seem to far fetched.

Quite naturally I wont be conducting these tests offroad, and will go pretty easy on the throttle as not to ruin the gears.

Once again, this is intended as an experiment, as I cant seem to find any info regarding such a setup. And, the way we (electronic engineers) see things, problems can be solved three ways: mechanically, electrically or, if everything else fails, in software.

And also, Im tired of everyone doing like everybody else just because its the safe way. There are some really awesome hacks on this forum, and I intend to check what this one yields (and what downsides are to it).

The parts are still in the mail, will update when things happen..

 

[gapjr]

"thumbsup". Go for it man. Somebody has to be the first. I'd be interested to know the results. Good luck with it. I had one of those ezrun 5.5t motors in a losi desert truck and it was nearly uncontrollable.

 

[squatch71]

you didn't say what this will be used for??? my cc01 has a 60T and a 16T pinion in it..has all the speed I want and slow crawling I need for trails...are you racin yours with a 5.5T???

 

[ol puddin head]

65t in mine is way too fast for me. i'm looking for a used gru now.:mrgreen:

 

[ovstebo]

@squatch71: Im currently not using it for anything, as its still being shipped. If you read the previous posts you can see that its intended to be dramatically low geared, thus it will probably not be very fast at all. The intention is actually to have a very dynamic speed at near-halt-speeds.

Reason Im starting this thread before I even got the parts, is that shipping takes long time. That means if I forgot to order something, or should consider something, it will take 2-3 more weeks for the new package to arrive, and so on.

I have to order the GRU after assembly and testing of the 5.5T, as I will be using the setup to determine the needed gear ratio.

An update for now: I have acquired a GPS, which I hope can be used as a speedometer, a Garmin eTrex HCx. If anyone has any experience using this GPS for measuring speed, I would greatly appreciate some hints or tips

 

[Smoke&Mirrors]

I had a 45t with a 16t pinion in mine and it was a little too fast with too little torque. I swapped in a Novak 55t with the same pinion and it gives great torque with a nice scale wheel speed that is faster than I can walk and enough to bump or shoot it up over obstacles. I'd be interested to see what a 5.5t is like.

 

[ovstebo]

Well, now I've received most of the bits and pieces, but the motor is still being processed somewhere. Anyway, I have started building the cc01 chassis with a couple of precautions:

1. I will only connect the rear wheel drive. That way I hope to gain some speed when I measure, and I will ruin half as many gears if disaster strikes"thumbsup"
2. I will otherwise try and keep the chassis as stock as possible, with the obvious exception of a ball bearing kit.

Have received some awesome new mech. parts (some axles, bearings and joints) from technobotsonline.com, that I will consider for the V2 part of the project. When fitting a GRU, I will possibly have to move the motor slightly, in order to get it the way I want.

I have also done some thinking as to what the weight of the ideal scale model should be, and my theory is that it should be as close to 1/(scale^3). That a 1:1 weighing 2tons, should equal a 1:10 model weighing about 2kg. The power to weight ratio should also be the same as the original one, so this particular car should have 1 1000th of its original power. That way, 100HP 1:1 should map to a 0.1HP, or about 70W. That again should map to about 10A at 7.2V. SO: Most esc/motor kits are way to powerful for scale operation.

 

[ovstebo]

The motor and esc have just arrived, and was quickly added to the chassis. Have not been able to test it outdoors yet, but it is, as expected, way too fast. Just how much I want to reduce the gear is yet to be found out by trying it at full speed. Also there is a small forbidden area in speed between still and lowest speed, which I would like to be as small as possible.

 

[ovstebo]

The ESC and motor:

Mounted in the CC01:

 

[seabeejeep]

PLEASE GET VIDEOS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"thumbsup"