That's cool, you keep working, I can't wait to see this thing done!

I "got-R-Done"!
 

I've been told to "get-R-done!" So I got her done.:yes:

Last night, after installing the diffs, I tried it on 4S Lipo with the 4130. VERY smooth! The cogging is gone just like I hoped it would be. I mean don't get me wrong, this isn't a Rock Crawler.

I couldn't stab the throttle from a dead stop without it acting funny, but if it was rolling 2mph or more, any throttle setting was fine. WOT would top out VERY quickly. With the Phaltline tires, it's VERY quiet running.

The 4130 being 305kv, top end was still low, probably 30mph or so. This 4130 IMO is the ideal choice for a HV setup. I think performance would be amazing on 8S Lipo.

I ran it around for about 10 minutes, then came back inside to do the motor swap.

The motor change went well. I made another motor shaft for the 4120/14 (660kv). CVD spacing is easy to set on this. A test fit without the set screws in the endbell allowed me to perfectly center the dogbone spacing.

This morning I put on 2 Lipo packs that are 5000mah 7.4v 2S1P each. I started the stopwatch at the beginning of the run and had my temp gun in my pocket.

I ran it around in the yard, then up and down a long stretch of asphalt combined with some running in a grassy lot. The grass is about 4 inches tall there.

Top Speed is MUCH better. I don't have a speed gun, but it's doing 45mph+ I'm sure. This platform is very smooth, much more stable than the E maxx. The Phaltlines stick to concrete/Asphalt like glue. I spent alot of time doing high speed runs up and down the road, but jumping off in the grassy lot was fun too.

Acceleration is very good on 4S Lipo. I'm not seeing it flip over backwards from accleration like the E maxx will, but we are alot lower to the ground and a couple pounds heavier too. Brakes are good set to normal.

After several top speed runs, according to my laser temp gun, the ESC was 85 degrees. After checking several times, even after running in the grass, the hottest I seen the motor was 95 degrees. Ambient is 40 degrees outside this morning.

4S 5000mah lasted 32 minutes to the 3.0v per cell cutout.

Temps are very well in hand, I think we can crank it up. I see the 4120 handling 6S Lipo quite well. That's when we will see the torque/speed increase and it will become hard to control. I'm sure it will wheelie at speeds then.

I'm going to try a few other battery combinations. Then I will get some video with sound. It will show how quiet this thing runs. I like it, this is going to be alot of fun. :yes:

Sweeeeeet! Time to go buy some aluminum L for my 1/10th solid axle truck :D I have been using outrunners in cars for so long, seems that I should have tried this by now.

Right on Sikes!

At some point after you've had the opportunity to play with it for a while :) would you mind giving an accurate list of parts (#'s and source) for this conversion? I almost bought a revo roller 3.3 off ebay for $285, but I had to get my 4wd Academy SB V2 Pro first. ($268 after shipping from amainhobbies with a coupon :)

I am going to sell off all my nitro stuff >done with nitro forever!!!< and start persuing the DDR, so any info is important.

Thanks for sharing the build with us all, guy's like you are what make this hobby a blast.

That is so very true. Sometimes we need to see other people try stuff out before we can decide whether its a good/viable idea or not. Sike is a trend setter; saddly the planks on noob central couldnt grasp the concept and would rather play with titans or cheapo 600 motors- their loss!

I am totally in love with the concept. Who needs a stinkin gearbox when you have people like Sike? The weight savings would be HUGE! (rummages for 3032 outrunner)

Weight down low, no gearbox to fail, efficient, and soooo slick. What's not to love about it? (mabey the high voltage is a little pricy but you do get what you pay for) did I mention efficient and less stuff to break?

I guess that I should do some mods to the old direct-to-diff redcat and see what it can do. Need to find a lower kv motor, most likely a 600-650 would do. That will allow me to put some taller tires on it and it will be more off-rad capable.

The main benefit I found was that there was so muck more room on the flat chassis with out the center diff/trans there. Batteries could be placed on either side of the chassis and the balance was great.

Any ideas on a good out runner with 600-650 kv that would run 5s well and have a 5mm shaft? Here is the info on the motor I am currently using, would like to keep the same diameter if possible:

Specifications:
-Rpm(Kv): 833Rpm/V
-Continuous Currect: 50A
-Max Currect: 70A
-Watt: 980W
-Max Eff: 98%
-Recommended Rotor Prop: 8 x 4 to 15 x 8
-Weight: 150g ( Motor Net Weight )
-Total Length: 78.2mm (include Front and Black Shaft)
-Motor Body Diameter: 37.1mm
-Shaft Diameter: 4.98mm(Front and Back)
-Shaft Length: 15.1mm (Front) and 14.2mm (Back)
-Recommended Input Voltage: 8 - 23 Volt

looks like the dimensions of a 28mm stator motor. 980W for a 6ish ounce outrunner? Certainly not constant, and the efficiency looks fishy too.

A 3026 would be close http://www.innov8tivedesigns.com/pro...products_id=80 and you could do a custom wind.

Trend Setters.
 

The good thing about trend setters is that they lead the way for others, which in turn creates a market for the parts involved in a conversion poject like this one. So hupefully within a reasonable amount of time this can bring the price of this conversion down. Then more of us can afford to bring our trucks to the same level without breaking the bank for a hobby truck. Creating a group of vehicles that can race at that same level with less weight, less broken drivetrain parts, and increased efficiency, not to mention a much cleaner experience all around and less frustration unlike Nitro. Way to go Sike for going all the way with this project:intello:.

It kind of reminds me of the aspects of the NASCAR organization which sets things up so that having vehicles that are vitually identical creates the situation which means that winning any race is soley in the hands of the driver and his crew (the human factor). This has the looks of a very sucessful build Sike. Thank you for sharing it with all of us and keep up the good work.:yipi: I for one look forward to the completion of this one so we can all learn from your work.:lol:

Yah, a $70 motor that's 90% efficient is a real good place to start.

I've got a thread about CF parts open now, I'd love to see a bolt in chassis that has integraded battery trays, motor mounts (mabey a motor that runs well on 6S when the MMM finally shows up) all the misc. bit and pieces and the diffs in a kit to make the ultimate e-Revo conversion.

I would spend money on that, and I think the guy's that see it would too. Especially the guys that are dealing with the nitro dissapointment and already own the revo.

This "Direct Drive to Diff" method definitely has plenty of advantages. But to keep everything in perspective, there are also disadvantages:

-harder on diffs, due to lack of torque control (slipper clutch) or a way of transferring power (center diff). But since the vehicle should be lighter this way, that means less mass to move.
-battery placement - I like to run a single pack on the opposite side of the chassis from the motor. However, unless you have a Losi 8 or 8t, the motor will need to pretty well centered, which can disrupt battery mounting on narrow truggy/buggy style chassis.

For my MT2, the chassis is way too narrow for the diameter of my motor to run a battery on each side of the chassis, along with the servo up front on one of the sides. So, I'm gonna offset the motor to the left, and stand the steering servo up (on the left). That way I have maximum space on the right for battery mounting. There will also be the brake servo and maybe the ESC at the left rear, behind the motor.

I considered the clutch idea, I may have to look a little better into that. Was thinking for cogging issues (if one were not to mod the diffs) but I could see where having it for drivetrain insurance is smart too.

I think a clutch between the motor and each diff (two clutches total) would work.
The idea I have come up with is more or less a ball differential with no gear and one of the outdrives will be replaced by a part that mounts to the outrunner's shaft. One problem I can see is getting this slipper clutch-thingy able to handle that much torque - normal slipper clutches spin at higher RPMs so the torque is less, but here, the RPMs are lower so the torque is greater.

Then, a one-way could even be used after the front slipper clutch to give us rear-wheel braking only, allowing us to pitch the rear end in turns.

Also, it turns out that the shaft that came on my motor will work to mount the dogbone cups to with only slight modifications! And the 6mm shaft I have is about 0.0015in. larger in diameter than the shaft that came on the motor (doesn't fit).

Videos!
 

I put the E maxx Tires on with 4S Lipo. Here's a taste of what it's doing. :yes:

http://i160.photobucket.com/albums/t.../th_ERevo2.jpg

http://i160.photobucket.com/albums/t.../th_ERevo1.jpg

Second vid looks scrunched. I think the aspect ratio got changed somehow.

I think I need to shim the rear diff, pinion to ring. I believe I heard it pop a few times. It sounds like the pinion is skipping a tooth when I jump and land.

What shims do I use?

I think the aluminum diff cup is a good idea also. The plastic one must be flexing and allowing this to happen.

Bullet Proof Diffs are a must. I won't run it on 6S until I get this fixed.

Overall, it seems to be working very well. :yes:

cool vid... I really like the sound it makes... it's so quiet...

Thought.
 

it is so quiet that it almost makes you want to put a sound system in it that makes the sound of a nice muscle care to match the awsome power that it has. Maybe a Shelby Msutang GT, or a Dodge Viper RS:yipi:. That really is a cool setup though Sike:yes:. Where to go from there?? That is the question??:lol:

@Metalman:

Please share your ideas if you come up with something concrete on the shaft/slipper thingie. I believe in a Monster Truck, a clutch assembly ONLY on the rear shaft would give you the results that you're pondering.

The rear diff is the one that takes most of the abuse. This would retain full braking power with the front diff.

On the shaft material that you have, cut it to the length you need, stick it in a drill press, then sand it down with the chuck spinning at a good speed. Do a little at a time and check it. You might be surprised at how well this cuts. I always used a motor bearing to check the diameter as I went.

This type of setup is hard on the diffs. That's why I've went to the lengths that I have to insure diff toughness. I think if a diff is tough enough, it should be able to withstand jumps with full throttle landings. Or at least, I think that should be the goal.

I ordered the Aluminum cups for the diffs a few minutes ago. A little extra insurance against internal flexing.

I also took out the rear diff and redone the shimming. I wanted to tighten it up, so instead of 3 (.2mm) shims behind the pinion, I now have 4 there. I also put one between the ring gear and the bearing to move it over just a tad.

When I put the diff back together, it spins freely with no pinion play at all. There was some play before.

Where to from here? The only way to go is UP. :lol:

Up in voltage. I'm going to be playing around with this setup for awhile before I get the money for a HV ESC. I want to try it on the 4S A123 setup. I really like the A123's.

I also feel more confident now about the diffs, so we can proceed.

HV ESC choices that I'm considering are either the Jazz or the MGM.

The truck will get really crazy on HV. On HV, I might decide to go back to the 4130/20. It will have more torque than the 4120 does and get all kinds of crazy since HV will spin it up very well.

Glad to see how well this turned out with the proper rollout. I picked up a 4ft section of L channel today. Time for more "research" into this. Got any taller tires you could throw on your rig to test a higher rollout ratio?


Maybe I missed it, but what ESC did you use in the vid? Sounded like a quark to me.

Did you find it at Lowes?

I would really like for you and the other guys that plan on doing a Direct Drive to Diff conversion to share our findings with each other. I think if we compare notes along the way, we can all learn from it.

In remembering our conversations about Wye and Delta windings, I think you will have a vantage point in building your conversion. I suspect the Wye Termination wound with fewer turns to match the Delta kv rating would work better with this. MUCH more torque.

I tried the Phaltline tires that are 5.5" tall, then I put the E maxx tires on that are 5.75" tall(same as the Revo). They both work well. I don't think I would want to go any higher geared than this.

Even an outrunner needs to spin up a certain degree to make it's power.

With the 5.75" tall tires, roll out is 4.2" per revolution of the motor. Think about that. That's alot.

I think this helps to confirm the statement that "An outrunner motor makes 5 to 7 times the amount of torque as an inrunner does".

Increasing the ratio would just bring back cogging on startup. This cogging could completely be eliminated by the creation of a custom sensor based outrunner setup OR possibly be improved with some internal mods to the ESC. The resistors in the feedback leads could be changed to ones of less resistence.

Most ESC's on the market are designed to work well with a wide variety of motors, inrunners and outrunners alike. I really think startup routines AND Anticipated spool up speed of a motor are based on a curve that is a rough average of how most motors perform. I don't think this "curve" fits every application ideally.

I'm using the 80amp Quark ESC on this right now.

I went back and read over the "red cat" post and studied the pictures a bit more.

Can you get shorter CVD's for that setup?

I'm with John on his recommendation. The Scorpion 3032 motors would work well also. There are two ways to increase starting torque with a motor change. Increase stator diameter OR increase stator length. All the Scorpion 30xx motors use the 5mm shaft.

Thanks for the recomendation. I can always cut and weld my center dog bones to the correct length if needed. A longer stator would be the best bet for this setup as it needs some more torque. Does axi make a similar sized motor to the scorpion 30xx motors? Which scorpion/axi would I want to use? Thanks a bunch for the advise, I have plenty of inrunner experience, but not a wholelot of outrunner testing under my belt!

What does the Redcat weigh?

This motor looks pretty good for the specs you gave.

http://modelmotors.cz/index.php?page...e=12&line=GOLD

That is AXI's website. They make alot of different size motors.

PS. A little off topic, but was there a special bearing that you used on the 1/8th diff pinions? I know you were having trouble getting them to hold up

Thanks Sike, may have to scare one of those motors up. On the weight issue, the redcat is very light, maybe the weight of a rustler sans motor and esc.

I use the std HB bearings that came with the diffs. I had an issue with a stock revo pinion bearing that the race came apart and the balls made their way into the ring and pinion gears. All of my revos run stock diffs at the moment, I was building a killer maxx / racebomb truck and it is currently in a box at work awaiting time and interest from me!

It's funny you mention the averaging of an ESC startup to fit most motor types. That is how it was described to me by Pat @ Castle. Having different settings for slotted, slotless, and high pole count motors would give the best performance.

Im glad you brought back up Wye vs Delta winding. I need to look back into that. I have an empty 3032 stator sitting here ready to wind.


Lpimp- The 3032 is almost 8 ounces. It will be plenty of motor for most any smaller builds, and very robust from the front ring bearing. Think of the motor weight about the same as an inrunner. You would want 6 ounces of motor for a stampede, so stay with that same heft and maybe add a bit since you will lose gearbox weight. Motor weight is a pretty good indicator of how much power it can produce.

Ok, but I would like to have a lower kv motor, somewhere around 600 - 650kv, so that I can power it with 5s and run taller tires. Not looking to do 70mph, something in the mid 40s with good low speed driveability and less heat production than the current motor.

Choose the 12 turn then, or wind your own for even higher voltage handling. They come in kits too. I don't think changing the Kv will change the max usable height of tire either, only the motor size and voltage used. Time will tell on that though.

http://www.innov8tivedesigns.com/pro...products_id=83

The winding does have alot to do with how much torque she makes.

In comparing this, think about the "turn" ratings on brushed motors. The fewer turns meant you had a high speed motor. If you have many turns, then you have a low speed motor that makes more torque.

A "Race" motor in the 540 size might have as few as 4 turns. But a Lathe motor for a rock crawler might have as many as 30 turns.

Remember the "wrap the wire around the nail" experiment? How did the number of wraps affect amp draw and how strong the magnet became?

What are you going to use to lock the stator to the bearing holder?

Scorpion uses 30awg wire to wind their motors with. What Ga. wire are you planning to go with?

I've asked some questions and did some research on winding wire size. Lucien told me they use 30awg because it's easier on the workers fingers. :whistle:

There is only so much room between the stator arms for wire. IMO, a larger wire size might be better. Something like 24 Ga or 22Ga.

If you look at the amp chart for wire sizes. Winding wire is really being pushed to it's limits, but the coating is high temp so it works.

There is an entire science to motor winding. I do want to try it. Maybe get a kit from Lucien, and fix the stator to be removeable. I could wind it, try it, then take it back apart and re-do it. Recording results like this could be very educational.

The reason I say Kv probably won't have an effect on tire size is this: we are working within a fixed stator size and copper saturation for any given motor. Whether it produces 1200 watts with amperage or voltage is up to the wind count and matching voltage. For your nail example, if we fix the weight of wire to wind around the nail we shall get different wind counts based on the AWG used. At least for a fixed voltage, the larger AWG wire will have a stronger magnetic feild.

I do know that kt is directly relational to kv, but as kt goes up the amp draw of the motor goes down too- making torque guessing impossible without actually testing.

Not sure where I am going with this really, I think I have convinced myself that wind count might actually change how hard you can gear the motor :lol: I do know for a fixed voltage a higher turn motor can be geared a bit higher, but that is based on heat and wattage loading of the motor from my understanding.


I ask this: do you think a 10t on 20v or a 5t on 10v would have any startup differences assuming the cells and ESC can deliver the power? In my time I have messed mostly with gearing and voltage and kept wind count constant.


As for building the 3032, I was gonna fix the stator with 30min epoxy or green locktite. The 3032 isn't something I want to take apart multiple times as the ring bearing is pressed in. My plan was to use 24awg wire most likely, I have a 5lb spool of it. Another thing we could mess with is magnet count and arrangement. Probably want to stick with dLRK or 12 slot /16 pole ABCx4 construction for direct drive.

Yes, the larger AWG wire will have a stronger magnetic field because of what? Total Power output as far as watts goes, depends alot on the total resistence of the winding. What affects this? Total wire size used,(multiple strands even), and length of the run.

If you try a Wye Termination winding, just remember total run length is about twice that of the Delta. The thing that intrigues me about it is, it is pulling on 8 magnets at a time instead of 4. This gives a torque bonus at the expense of kv. That's why I was suggesting using fewer turns on each pole.

"I ask this: do you think a 10t on 20v or a 5t on 10v would have any startup differences assuming the cells and ESC can deliver the power?"

I think idealy they would start the same if the strand count was such to make the resistence equal. The 5T would make more heat and draw twice the amps. The 10t would run cooler and be more efficient.

I looked for the Green Loctite at a local "O Reilly" Auto parts store. They had the Permatex brand. Come to find out, Permatex Green isn't exactly the same as the Loctite Green, because it's medium strength. Where can I find the Loctite Green?

I do believe there is a magnet/winding configuration that will work better than these "out of the box" Delta Outrunners. I hope you find it.:yes:

I just did a run with 6S1P A123. I forgot to change the low voltage cutout though. With the LVC set at 3.0, the run lasted 11 minutes.

Performance is good. Temps are well in check. The Batteries got up to 120, but the ESC and the Motor remained cool. ESC at 97, Motor at 95 degrees.

A123 with only 1P, the voltage seems to sag ALOT under a load.

I'm gonna try 5S1P 4000mah Lipo next. :yes:

I have the permatex green, didn't realize it was medium penetrating. I will probably stick with epoxy then. Only place I know that carries loctite brand would be online retailers.


The conversion from Wye to Delta is 1.7 winds, so a 10 turn Delta is equivalent to a 10/1.7 turn Wye - almost 6 turns. This keeps kv constant. The conversion from a 10 turn D at 980kv to a 6 turn Y is as follows: [10T/1.7=5.88T] [980kv x (5.88T/6T)] = 961kv with a 6T Y termination. Substituting the 6 for any other wind count will give kv with Y termination.

Looks like the 3032 with a 6Y on 4s lipo will be pushing it pretty hard. 15k rpm, don't know how well the ring bearing will take it.


One thing I didn't think of for startup is the length of wire and the inductance on a coil. The ESC will sense a higher strand count coil better, so maybe this could cause lower kv motors to start up better. Not a product of motor torque as much as the ESCs increased ability to see a higher wind motors position? The issue with total motor power always gets me when thinking of startup. To me any 1000watt motor should start up the same unless the wind count is on the extreme end of things. Probably not the most accurate assumption.

Oh yes, the scorpion stators are keyed. If you had the means to mill a keyway into the bearing tube you could easily have a removable stator.

I ran the 3032/10 in an E maxx. It was running pretty warm. It would start good and had great acceleration though. The 3032/10 is 823kv. You might want to back down from the 980kv some.

The 5S1P 4000mah run lasted a little less than 20 minutes. These are older 10C cells. I've ran them pretty hard all summer in the E maxx, so I doubt they are quite putting out 4000mah anymore. I bought these batteries in Feb.

Battery temps are 120 degrees. Motor is at 100 degrees and the ESC is 115 degrees. All still well within range.

The 5S Lipo setup runs exactly like the 6S1P A123 setup. I couldn't really tell any difference as far as performance goes.

I'll try 6S 4000mah Lipo next. We should see some real gains then.:yes:

What's Amps is that motor rated for?...

The 6S 4000mah Lipo run lasted 22 minutes. Motor is at 105 degrees. Batteries are at 102 degrees and the ESC is at 115 degrees.

I think the Monster Pro 125 would suit the 6S setup better. I believe I seen the 80amp thermal while running WOT in the grass. First time for this, I was a little shocked and puzzled.

This is harder to control. Severe Tire Swelling and a large increase in Top Speed. I believe we have surpassed the 60 mph mark. I was running on the outer road by the interstate. I can almost keep up with traffic! :yes:

It will wheelie at speed now, especially in the grass. It will spin all 4 of them on the asphalt.

I'm very impressed with the motor temps. The fan seems to be working to keep temps low. Seeing the fan as an option is alot of the reason why I decided to go with AXI. I think this motor can do well even on 7S Lipo.

I love the Revo. It handles so much better than the E maxx especially at high speed. The suspension is so much better.
:yes:

Here are the specs from the Manufacturer's website.


4120/14 Specifications
No. of cells 12 - 16
4 - 5 Li-Poly
RPM/V 660 RMP/V
Max. efficiency 85%
Max. efficiency current 20 - 40 A (>82%)
No load current / 10 V 2 A
Current capacity 55 A/60 s
Internal Resistance 41 mohm
Dimensions (diameter. x lenght) 49,8x55,5 mm
Shaft diameter 6 mm
Weight with cables 320 g

The addition of the cooling fan increases it's current handling ability I believe.:yes: