Direct Drive to Diff E Revo Build

[sikeston34m]

Originally Posted by DrKnow65

Congrats, you just made the "favorite sellers" list.

Back to topic, if this setup is requiring gear reduction, what KV motor would you have gone with instead? (interested for a someday revo, more interested in a tomarrow kind of direct drive hyper7) or would these be two entirly different KV needs???

Thank You!

I feel like I chose the best KV available that would fit the space/shaft size.

The lower the KV rating, the more torque they are supposed to have. This AXI 4130 is rated for up to 8 Series Lipo in an airplane. On a HV (8 series or more) setup with the 4.3:1 gear ratio diffs, I think this setup would absolutely scream. The plastic shafts would snap quickly, severe tire swelling, hard to control, good things like that. LOL

The problem with the higher gearing is, the ESC isn't reading the EMF feedback properly because there isn't enough feedback from the motor at low rpm's. I feel like this is the source of the cogging. I think Brian, (a very intelligent person) is right about this.

I wanted to try this with the stock diff gearing. I have at least learned something about the lower rpm threshold for EMF feedback and sensorless control.

On 6S2P A123, the motor, is on the lower end of it's recommended voltage range. Maybe 18 volts loaded. On 8 Series Lipo (around 30 volts loaded), it would be much stronger. But this exceeds the voltage limits of my Quark and I don't want to blow it.

It looks like this project is stalled waiting on the Hybrid diffs for now. But when I do get them, I will first try the 4130 again before switching to the higher kv 4120 motor. It should be interesting and hopefully show more about the behavior of these motors.

[DrKnow65]

Ohhhhhhh I see, I missed the whole 8S-6S thing... and never put togeather the gears with the cogging (feeling like I need to go back and re-read the thread) I have watched it for awhile and read all the posts but I must have been too busy looking at the photo's :)

[johnrobholmes]

Yes, I am talking about the scorpion motors. I have a few built ones and a single kit here. I was planning on changing the magnets around and seeing how it would act at about 2000kv, but the ring bearing won't like the high rpms. 1000kv or less would be the ticket, it should really be ran close to 6s lipo instead of the 4s max that they are wound for.

[sikeston34m]

Originally Posted by johnrobholmes

Yes, I am talking about the scorpion motors. I have a few built ones and a single kit here. I was planning on changing the magnets around and seeing how it would act at about 2000kv, but the ring bearing won't like the high rpms. 1000kv or less would be the ticket, it should really be ran close to 6s lipo instead of the 4s max that they are wound for.

I have a 3032-12 on hand with the ring bearing. Is the ring bearing a press fit?

I didn't wanna just put it in a press without knowing, and break something.

[johnrobholmes]

Yeah, the ring bearing is a press fit into both the can and the faceplate. It takes a hammer to get the motor apart once it is together. You have a bearing press? Also, the rear of the can is just pressed onto the backside fan plate in some cases, make sure to check that and seep some locktight in.

[sikeston34m]

Originally Posted by johnrobholmes

Yeah, the ring bearing is a press fit into both the can and the faceplate. It takes a hammer to get the motor apart once it is together. You have a bearing press? Also, the rear of the can is just pressed onto the backside fan plate in some cases, make sure to check that and seep some locktight in.

I use a drill press with a 4 or 5 mm rod. Just prop it up in a vise the way I need it or use blocks.

I can put quite alot of pressure on one this way.

[johnrobholmes]

That is how I press motor shafts in and out, with my drill press and a 5mm flat punch.

[sikeston34m]

All the New parts are on their way

RCM 4.3:1 Ratio 1/8th truggy diffs
Center CVD's
AXI 4120/14 outrunner motor

Hopefully this build will get back "in gear" when they arrive.

[johnrobholmes]

I will be waiting! I have a solid axle truck that wants to be converted direct drive too :D

[DrKnow65]

Dont forget my hyper7 wants direct drive too :)

[rschoi_75]

just got done reading the thread. Bravo Sike. Well done.

She is a beauty.

[sikeston34m]

Got a little bored waiting on parts to get here. So I decided to enlist the Revo in a weight loss plan!

She went from 9lbs 8 ounces, without batteries, to 9lbs 1 ounce. When I change motors, another 4 ounces will drop to make the weight 8lbs 13 ounces. I'm thinking about maybe trying the Badlands tires/wheels, so that might shed a little more weight.

I decided to get rid of those gawdy "sideboards". I shaved them on down. This allows me to lay my Lipo's down for an even lower center of gravity.

Ok, maybe 4 Series 10,000mah Lipo's are a bit bulky. How about 4 Series 5000mah Lipo?

OR, if I can settle on a HV ESC that I like, How about 8S1P A123?

I also trimmed and slimmed up the motor mount some.

My Tower Hobbies order should be here tomorrow. The rest of the parts will be here either Tuesday or Wednesday. I'm ready to get this thing going.

This is a very cool project. It is really tempting me to try something like this... Also, how heavy are your 8s1p a123's? I'm thinking of dumping my 4s 8000mAh and going HV...

Bye

[sikeston34m]

Originally Posted by cemetery gates

This is a very cool project. It is really tempting me to try something like this... Also, how heavy are your 8s1p a123's? I'm thinking of dumping my 4s 8000mAh and going HV...

Bye

8S1P A123 is 1lb 6 ounces. What ESC will you be going HV with?

[sikeston34m]

Do these Wheels and Tires look funky? Good for Asphalt Speed runs I think.