Savage XL outrunner conversion

*Update*

I received the outrunner today, and it is bigger than i thought.
But it fits pretty good actually.

I started to look for an aluminum motor mount and i finally cut an old rc chassis to fit.
I bent it and drilled the holes (there were holes before too )
And here are few pics:

Before:


Motor comparison: the can-motor used before and the outrunner



Then a picture after my work:



And some detail-shots:



The bending looks way more worse and it really is.

Thats all for now!

Regards, Andy

[Manne]

Intresting project for sure:). Just a question, I thought the outrunner would be at least as long as the can motor? and doesn´t grass and stuff get stuck in/on the motor?

Keep up the good work!

Yes, indeed i have to think about an appropriate dust protection and cooling solution.

at least as long as the can motor

Why did you think so?


Q: Would it be enough if i cut a notch into the shaft of the motor instead of a end-to-end drill-hole?

Thanks
Regards, DanteX

[Manne]

It just felt like with a directdrive system you would be in need of a HUGE amount of torque to get the rig moving without too much cogging, and i was thinking "longer motor, more torq" so I´ve got suprised when I saw how short it was

Next week i will see how it performs and then tell you if it worked :)

Happy Easter!

[Manne]

Sounds good. Happy easter on you too

[suicideneil]

If by notch you mean a flat spot to attach the drive cups, that'll work fine- maybe add a little dimple too for the setscrew to bite into.

Thanks, thats what i was talking of.

I will try it like you said!

WTF?!

Well, a few minutes ago i completed the reassembly of the savage and i did a test drive.

But this thing has no power. It can barely get speed.

If i let the wheels spin freely it balloons that much.

I think there was something wrong with the scriptasylum calculation.
I had to stop the test because the motor got almost too hot.

Any suggestions for improvement?

[Semi Pro]

Originally Posted by DanteX

*Update*



Motor comparison: the can-motor used before and the outrunner

we put that exact same motor in an emaxx, just some advise, take it apart and reshrink the stator leads and then ca them down, or the motor will eat them for lunch

[Semi Pro]

Originally Posted by Manne

It just felt like with a directdrive system you would be in need of a HUGE amount of torque to get the rig moving without too much cogging, and i was thinking "longer motor, more torq" so I´ve got suprised when I saw how short it was

its going to cogg

its not the length it the diameter that makes a big diffrence in torque with outrunners, to not cogg you would need an outrunnertwice that size

[simplechamp]

Originally Posted by DanteX

WTF?!

Well, a few minutes ago i completed the reassembly of the savage and i did a test drive.

But this thing has no power. It can barely get speed.

If i let the wheels spin freely it balloons that much.

I think there was something wrong with the scriptasylum calculation.
I had to stop the test because the motor got almost too hot.

Any suggestions for improvement?

The values you used in the calculations are correct, but physics makes the calculated speed impossible with this setup.

Look at your rollout values, they are over 6:1. This means for every 1 turn of the motor the wheel will roll 6 inches, which is WAY too much. Should be closer to between 1:1 and 2:1.

With that high rollout you will have no torque at all, even with a low-kv torque heavy motor, because there just isn't enough gear reduction. That would explain why if you pick it up off the ground and let it freewheel in the air the tires might balloon huge, but once the motor is loaded up with the truck on the ground it can't get up to speed. It would also explain why the motor got so hot.

[Semi Pro]

what kv motor did you get?


we were geared for 40mph and it spun the wheels all the way to 30 on 5cell..........just didnt last long

[simplechamp]

Originally Posted by Semi Pro

what kv motor did you get?


we were geared for 40mph and it spun the wheels all the way to 30 on 5cell..........just didnt last long

Was the E-maxx direct drive though? You probably had a pinion/spur and transmission which all lowered the gearing.

[Semi Pro]

Originally Posted by simplechamp

Was the E-maxx direct drive though? You probably had a pinion/spur and transmission which all lowered the gearing.

no it was direct drive, let me see if i can find pictures for you