Custom Outrunner Setup

[Takedown]

The whole purpose of this project is for less stress on the outrunner. I dont care if their is power loss or anything of that such. I just want a healthy outrunner at all times possible. Plus this is something new and I decided to give it a shot.

[brushlessboy16]

Originally Posted by Takedown

DrKnow is exactly correct. The reason I want low stress on the outrunner is because I dont want the front bearing to blow and because i dont want anything like the grub screws etc popping out while driving. "That wouldnt be a good situation to be in while doing speed runs".

You say that u want to save ur motor, but wouldnt running all 1800watts of power through two ends of the shaft.. guessing around 900w on each side.. but with this setscrew u have all the power going through one.

[Takedown]

Thats double the stress on the outrunner. Thats what Im trying to eliminate.

[_paralyzed_]

Guess i beat you to it paralyzed :D

d'oh!

[_paralyzed_]

Thats double the stress on the outrunner. Thats what Im trying to eliminate.

Either %100 stress on one side or %50 on both sides, it's not more stress, adding more components adds more stress, K.I.S.S. Keep it simple silly

for all the forementioned reasons you are adding stress, I'm not sure on the thinking on this one????????????????????

[BL_RV0]

Originally Posted by _paralyzed_

balls

..............

[_paralyzed_]

you bustin' my balls BL_RVO?

[brushlessboy16]

lol wow, STOP BUSTIN BALLS Rv0! lol

[BL_RV0]

Plausibly...

I feel as though I should contribute to this thread via a "balls" joke...

Anyways, interesting idea Takedown, but I would say it is a bit inefficient as others have said. Inefficiency can lead to more stress sometimes too, so I think your idea may, at the very least, need some tweaking. DrKnow's idea about getting that one drive shaft parallel to the chassis is a start (which I see you noticed and are considering his suggestion).

Something about two center diffs that are locked just doesn't seem like a good idea either. Maybe you should just use two spur gears to achieve the same effect but with far less rotational mass?

[DrKnow65]

here are some constructive links...

First sikes outrunner e-maxx http://www.rc-monster.com/forum/showthread.php?t=9493 A real good guy to follow if you are looking into an outrunner. He's played with Direct drive revo's and outrunners galore. He even has hand wound an outrunner to make it perform better.

A link to the tamiya (thanks to five-oh-joe) http://http://www.tamiyausa.com/product/item.php?product-id=43532 a good demonstration of how-to.

You guys should offer advise, but keep it constructive and positive. Takedown is obveously a thinker, he's come here and thrown out an idea, asked for help with it, and even drawn us a diagram of the parts so we can see what he's saying. He could have come to some good conclusions on his own given the time and the encouragement. Every successful inventor has built on an idea that failed and was evaluated as to why. More attempts were made and failed again. The process repeated until the awnser was found, then it was something to behold.

That said, there is merit to only using one end of the outrunner, you eliminate the torsion of having the front end inertia fighting the back end inertia. How many outrunners have you seen that actually snapped the output shaft from it's own torque?


I would think that the most stress free outrunner/ center diff setup would be an open center diff with some insanely thick fluid, a pinion gear mounted directly to the outrunner via a slipper clutch, you could add a secondary bearing support on the outer part of the pinion gear shaft, and of course overbuilding and underusing every component. That's me and I may not see something Takedown might. He might throw out something and not see something I do. If we're going to help, we should.

I, personally, would like to drill out the shaft of a large outrunner (mabey an 8mm shaft) so that I could put a 4.5mm shaft through it. I would then put it directly in line between the center diff and the rear end. Connect the motor shaft (8mm with a 5mm hole in it) directly to the diff case (via a slipper) and let the rear diff output go through the 4.5mm shaft to the rear end. The outrunners mass would be low and centered, the center diff would keep the front and rear ends from fighting, and the slipper would keep the gears happy. Use KV and voltage to tune the setup like sikes did with his DDRevo.

Now look at the little blue writing at the bottom of my post to figure out why it's only an idea.

[lincpimp]

Ok, correct me if I am wrong, but the purpose here is to reduce the load on the bearings and shaft of an outrunner motor?

The gearing will not be used to alter the ratio?

If so I have a much simpler idea to help the bearing stresses on the outrunner. If your outrunner has an 8mm shaft, mount it in the chassis with a std mount from the non rotating end. (just like any direct to diff outrunner would mount.) Then make a pair of bulkheads that fit on either end of the motor, and are mounted to the chassis. Place large bearings in these bulkheads that have an 8mm id to support the shaft of the outrunner. Then just place some sort of outdrive on the shaft and use dogbones to connect with the diffs. Motor is mounted low, no addl gearing to fuss with, less rotating mass, and the shaft is fully supported by the bearings in the bulkeads, not by the outrunner bearings. All the outrunner has to do is fight the rotational torque, and a decent motor mount can handle that. Plus the bearings in the bulkhead can be big, and wide. You may need a longer motor shaft to get everything to fit, but that is easy to find/make.

[DrKnow65]

I believe that the bearings are a concern Linc, I'm thinking he is also concerned about the rotational torque as well. I would think keeping a center diff is important. Looking back to sikes DDRevo it seems that killing diffs was a problem, the motor shaft was not the weak link, the diffs were.

I think sikes nailed it pretty good with the outrunner-maxx (3 diffs and a slipper). Only thing is, no extra support for the outrunner bearings, which seems just fine so far...

[DrKnow65]

I geuss could have just said "essentually putting the rear dogbone through the motor shaft of the outrunner" but there's alot involved.

[brushlessboy16]

But its still the samme load on the motor, and if td mounts it correctly Directly inline with the diffs then there will be no extra stress on the diffs