One thing I noticed during the 3 runs I've done today, The motor being so low acts like a balast weight. I did some high speed turns and I didn't flip this truck once today. I'm very pleased with the center of gravity.

Oh No! The RCM Hybrid Diff's are out of stock!

I tried emailing about ETA but the mail bounced back because the mailbox is full. :oh:

I wonder when they will get them again?

lol yeah you should try to cover up the motor as much as possible:lol:

Does the setup have enough torque to wheelies at speed? What Kv. is your motor?

So you are talking stator dimensions, not the outside dimensions, correct?

One of those Scorpions looks larger than the Axi, 40mm stator, 25mm length.

I don't know what rpm the motor is hitting, but I know an outrunner should be hitting 6500-7000rpm to get 45mph in a Revo with moderate ballooning tires.

No it will not wheelie. The AXI 4130/20 is 305kv. It's the largest motor that produces the most torque that will fit the space and the stock transmission output shaft.

Yes I'm talking stator dimensions.

On 6S A123, I figure I'm hitting about 5500 rpms.

Okay, well how much does the motor weight?

I find that odd that it is not doing wheelies with that large motor... I think this outrunner business is going to be a little tricky at 'sorting' out what works and what doesn't.

The AXI 4130/20 weighs 14.4 ounces. The 4120/14 weighs 10.9 ounces.

It is tricky sorting out what works and what doesn't.

I can't wait for the new E maxx to come out. I have that outrunner setup pretty much perfected all the way to the point of blowing the transmission. The new Tranny is 2 1/2 times tougher? We'll see about that.

The Quark does well with the E maxx outrunner setup, but I think the cogging in this setup has to do with what Brian said. There isn't enough EMF back pulses at low rpm because of the high gearing.

At 2.85:1 gearing, the truck moves about 6.5 inches for each rotation of the motor. Wow! I just did the math on that. That's quite a load actually.

At 4.3:1, this drops to a little over 4 inches. Big Difference. Hmmmmm.......

There's definately a sweet spot to this stuff. I could change the tire size, but I really don't want to do that. It's a Monster Truck! LOL

I'm not giving up on this, but where can I get some of the Hybrid Truggy diffs? Even just the cases, I'll come up with some gears.

just as an experiment run it on rwd to see if the less resistance makes it go a little faster

you would only gain maybe 1mph? maybe ♠2? :whistle:

OK on to the next phase of this project. Hybrid Diffs. I can get the cases, but I have to come up with the gears.

The Hotbodies gears are compatible with the RCM Hybrid cases. In searching for parts, I found this http://www3.towerhobbies.com/cgi-bin...?&I=LXLGX2&P=7

It appears to have a 50 tooth spiral ring. Would this be compatible with the 10 tooth pinion? Here: http://www3.towerhobbies.com/cgi-bin...?&I=LXJBM3&P=7

This combination would give me 5:1 diff gear ratio which is even better IMO than the 4.3:1

With the Emaxx, from input shaft to tire the ratio's are:
1st gear: 5.62:1
2nd gear: 4.57:1

5:1 is perfect! Power it with a AXI 4120/14 at 660kv and watch it fly!

It seems there is another issue with the Hotbodies pinion. Here we have a 8mm shaft with no hole? What's the answer to this?

Maybe this? http://www3.towerhobbies.com/cgi-bin...?&I=LXFWS2&P=7

I could turn the cvd's around backwards and put the dogbone end at the diff. Are the two compatible though?

Hmmmmm.........I wonder.

It says the 50 tooth diff is for a LSP, so I'm not sure to be honest. Just use a standard LSP cup for the pinion.

Put this on the pinion and put the dog bone end into it. Cvd end can go on the motor shaft.

http://www3.towerhobbies.com/cgi-bin...?&I=LXJBE9&P=7

Mike sells the diff output shafts that can be used to put the stock silder style driveshafts on the hb diffs.

http://www.rc-monster.com/proddetail...d=RCMdiffshaft

Ok, here's my parts list that I plan on ordering.

Towerhobbies order

Hotbodies Output Joint Cup(pinion cup)
Stock #LXJBE9 (order 2) ($3.39 each)
Note: Tower is out of stock-Ebay has them

DuraTrax Metal Set Screw Asst. 4mm (12)
Part # LXTW57 ($3.39)

THS Racing Center CVD Set Revo 3.3
Stock # LXRLN4 $37.99

2 - Hot Bodies Spiral 10 tooth pinion
Stock #LXJBM3 ($13.99 each)

2 - Hot Bodies Front/Rear Hardened Diffs (43 tooth spiral ring type)
Stock #LXLGXO ($41.99 each)

Pinion Shims
Stock #LXGPC9 ($3.89 each)

AXI 4120/14 Outrunner Motor (660 kv)
Stock #LXPPX8 ($129.90 each)

Total $279.92


RCM Order

2 - V2 Revo Hybrid Diff Cases $80 each
includes the 6mm output shaft conversions

$160 Total

As you can see, RCM's drop in Hybrid diff is alot cheaper than gathering all the parts. I wonder when he will have those back in stock? If it's soon, I will wait. If not, I'll go this way.

SuicideNeil's post is very helpful on building Hybrid diffs. Thanks Neil!!

http://www.rc-monster.com/forum/show...ht=hybrid+diff

wow you really went all out on that purchase eh.


I can't wait to see the new results.

http://www.greathobbies.com/producti...d_id=EFLM4060A

Have you considered the E-Flite outrunners? I hear they are very well received and have awesome power.

I don't get it, how can you be using a 650kv motor on 6s2p? This SHOULD be getting you over 50mph then?

E Flite outrunners look VERY well. They have caught my eye for outrunner setups. Opportunity just presented a deal and I picked this New AXI 4130/20 for $100 shipping included. I thought it was the right thing at the time.

There is a ray of hope for this setup with the lower gears. First I'm going to test the 4130 further. I expect to see the cogging go away, gain some really good low speed driving. It should have explosive acceleration, but not much top end.

The 3520-7 with 650kv does get me over 50mph in the Emaxx with a 4.57:1 final reduction ratio. I once installed a 3530 (don't know how many turns), but on 6S2P A123. It was VERY impressive!! Too bad the drive dog stripped on the transmission output shaft in the very 1st run! I got about 2/3 of the charge out, and it went out. Acceleration was crazy fast and the tires ballooned so much, I never really seen it's top end. Very hard to control, if over anxious with the trigger finger. Top Speed on it had to have been in the 60's. I have another brand new 3530 waiting on the New E maxx to tame.

I decided to shrink my Lipo's in Blue. Now they closely match the Revo Chassis. They are made from 5000mah 10C cells. Each pack 2S2P will give up 100 amps Continuous and allow me 150 amp bursts. I think this 4S Lipo setup will give me all the amps I'm going to pull and more, plus some healthy runtime.
http://i160.photobucket.com/albums/t...m/DSC06658.jpg
I should be working on making it lighter.

how much does it weigh RTR?

Without Batteries, it weighs 9lbs 8 ounces. This is a little heavier than I would like for it to be.

There is alot of material on the battery compartment sides that can go. I think it would be cool to draw out some lettering there that says "E Revo", then remove all the material except the lettering and a border. The compartment bottoms I will leave solid. It's a battery shield and worth the extra weight IMO.

There is some material on the bottom mount that can be removed. Let's not get too carried away though. We don't want it to flex.

The ESC mounting plate can lose some weight. We will leave it solid directly under the ESC to retain the heat sinking.

Each 2S2P 10,000mah Lipo weighs 16.7 ounces each. Isn't this about the same as alot of 7 cell Nimh batts weigh? This puts the truck at 11lbs 9 ounces.

I have a 4 Series 4000mah Lipo setup that weighs 14 ounces for the pair. RTR it would be 10lbs 6 ounces.

Hmm, it is a little heavier than I would have expected, but then again those are huge lipos, and that motor is definately a lump; but a nice lump! Where did the battery heatshrink come from, I would like to find some large diameter thin stuff, rather than the really thick stuff Im currently using (traps too much heat from the Nimh cells).

I found a supplier that has a color assortment, but the least you can get is 100 foot rolls of the stuff. PM me for the contact information.

I ordered 4 rolls of the stuff. Red, Black, Yellow, and Blue. The shrank thickness is 4 to 5 mils. It's close to Industry Standard I think.

The flat width is 3 1/4". I was thinking about adding this to my Ebay products. Anyone interested?

This width works for alot of popular sizes. Batteries in the picture from left to right are: A123 4S1P, 6 cell Nimh, 7.4v 2S2P 10000mah lipo, 11.1v 3S1P 4000mah lipo, and the one on the right is 7.4v 2S2P 8000mah lipo.
http://i160.photobucket.com/albums/t...m/DSC06656.jpg

SuicideNeil, you have a PM :yes:

I could go for a little of the black...

i could go for some of the blue....

I think you should put a little time into "blending" your bottom motor mount. It looks as though it could easily be an impact spot as low as it sits. I'd hate to see you bend it up. I wonder if there is a way for you to attach the stock Revo tranny guard to it?

I didn't get the chance to page back to the beginning of the thread, but did you cut out the motor opening at all? If not, you may be able to do this, and raise the motor just a few mm's (or not!).
Otherwise, great job!

Hmm, it seems like getting hold of that heatshrink will be very difficult since I in the Uk- they do ship overseas, but the prices for the rolls big enough for what I want are rather high..... I wouldnt mind some of that blue, 2 metres should be plenty. PM time me thinks.

SuicideNeil, You have a PM.

For you other United States Peeps, I posted the Auction. I'll fix you up.

Thanks.

Neil... there MUST be shrink tubing in UK, just keep looking.

It would probably be cheaper, over seas shipping is pretty expensive.

sikeston34m what auction? where?

Go to Ebay, type in "battery shrink" in the search box. I'm the colorful guy at the bottom. :lol:

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.

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 :)

Patrick del Castillo told me it was 10% of the kv. With a rollout of 6.5 inches that would put this rig at a min speed of .3 mph or so, but I would at least double that figure or more to be conservative. The startup speed of the ESC is not the same as the minimum sensing speed however, so it might be trying to start the motor up much faster. Once you put the new diffs in your startup issues should go away, especially when you volt up.


Volting up right now might even help the startup, if only making it more abrupt and violent.


I really dig the build, I love how low and clean it looks. I still want to try this, but I sold my revo a while back and the emaxx isn't getting parted out yet. I have a 3032 I want to try, should be about like a 4020

Aaaaaaaah, so there's some confirmation about what's going on here! I'm VERY sure that with lower gearing, this thing is going to be a BEAST! :yes:

The reason why I want to switch to the 4120/14 is the higher kv to work with the Quark. It will have more than enough torque to work with the lower gearing.

I'm wondering something about the new 4120 motor. It's 15mm shorter than the 4130. Is there enough room to put the mechanical brake back in there and go with a HV forward only ESC? An ESC like the Phoenix HV 110amp version might be a good choice then. The Voltage could be cranked up as high as motor temps would allow. I think that would be pretty high, since this setup gets rid of the heat well. Is there such a bracket for the brakes though? Before it was mounted on the transmission, which is obsolete with this setup.

Thanks for your compliments. The low center of gravity that this has, REALLY sticks it to the ground. It's gonna high speed corner VERY well. I know on gravel, I could turn the wheel sharp at 30+ mph and it would just go round and round like it was on ice, instead of tripping/flipping over it's front tires. LOL

I don't think I like the Revo tires very well. Will prolly be changing out to something else. The E maxx's gator tires grip really well for off road.

John, I'm sure you are looking at the Scorpion 3032, correct? I put a 3032/10 in a Direct drive to transmission setup in an E maxx. It was a great performer for the first pack.

You gotta think about how much we are pushing, jerking, and tugging on that stator with this type setup. I ripped the stator from the bearing holder. In other words, the stator spun loose and ripped the windings from the power leads.

At the factory, sometimes I think they don't loctite the stator on both ends. This appeared to be the case. Even on the AXI 4130 that is in this one. Same thing. A prop doesn't have brakes like we use constantly or the resistence of acceleration that we are asking.

I used Red Loctite between the stator and the bearing holder on the endbell side. I had to slow "bake" it at 100 degrees for about 6 hours to get it to set. Green Loctite is the Better choice. It weeps into the microscopic holes and sets quicker with no temperature increase. I would make a puddle there and it would soak in, then I would do it again. About 3 "puddles" soaked into that crack, so I think the void was completely filled.

I know you plan a custom wind, I just don't want you to learn the hard way like I did. Let me know how it works out.

:party: Waahhooooooo Mike is gonna build me some Hybrid Diffs!

Seems like the 4.3:1 ratio was the least in demand, so he thinks he has some gears laying around and he's gonna check on the rest.:yes:

Me thinks this project won't be held up for long. :yipi:

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.

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.