A2B ultramotor axle size? and thread

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whereswally606   100 kW

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A2B ultramotor axle size? and thread

Post by whereswally606 » Aug 19 2018 10:20am

I recently snagged a bargain motor off ebay. I have since replaced the bearing and taken out the busted internal controller.

It only came with one nut (a bit like hitler/lance armstrong) anyway the one it came with doesnt seam to fit. The flats measure from 9.80 to 10mm across the flats and a smidge under 12mm is the od of the threads.

Anyway i think the axle thread may be damaged so i may need some one with a lathe to help fix the threads. Are ultramotor axles oddball threads because the one nut it did come with never really threaded on right?

I feel i am making progress slowly but surely. have not tested the actually motor electrically yet but it looks fine.

Anyone have any experience with these, what replacement nuts to i need?
Distributing "Lebowski" FOC Controller PCB (Through hole) since 2016
Moped: Emax 110s 2009

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eee291   10 kW

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Re: A2B ultramotor axle size? and thread

Post by eee291 » Aug 19 2018 11:52am

I just measured it, you need M12x1.25 Nuts
Last edited by eee291 on Aug 19 2018 1:54pm, edited 1 time in total.

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amberwolf   100 GW

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Re: A2B ultramotor axle size? and thread

Post by amberwolf » Aug 19 2018 1:13pm

whereswally606 wrote:
Aug 19 2018 10:20am
Anyway i think the axle thread may be damaged so i may need some one with a lathe to help fix the threads. Are ultramotor axles oddball threads because the one nut it did come with never really threaded on right?
AFAICT, the UM I have from a Stromer uses the same axle nuts as my geared motors by Fusin, which are 12mm. Don't know what thread pitch that is, but probably whatever the default coarse thread for that size is.

They spin on easily by finger, until down to teh dropouts and tightened.


Regarding the damaged thread issue, there are posts over here:
viewtopic.php?f=2&t=95905
that discuss some easier ways of fixing that besides a lathe.


Almost certainly there is nothing wrong with the motor other than the internal controller, and even that may actually work if you could command it to do things. ;) At worst, a hall sensor might be bad, but these things appear to be really well made, and I expect the failures that do happen are probably caused by heat over time causing premature aging of components like capacitors, more than anything else. Hard to tell since the controllers are potted, and proprietary in operation and control systems. :/

I'd guess that if you could take a Lebowski brain board and use it to drive the powerstage inside that controller, it would work just fine. ;)

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eee291   10 kW

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Re: A2B ultramotor axle size? and thread

Post by eee291 » Aug 19 2018 1:51pm

It's not a Standard (Coarse) 1.75mm pitch it's a Fine 1.25mm. like I said, I just had that checked.

Same thing goes for all the other hubs I had until now, (MXUS,9C clones,etc..) they always have the fine pitch.

Ianhill   100 kW

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Re: A2B ultramotor axle size? and thread

Post by Ianhill » Aug 19 2018 3:15pm

I've got an a2b axle, nuts, torque arm, matching alex rim and spokes, I would give it away for free but I have asked about the lebowski board and got no where and ended up buying a inferior vesc,
I asked about an emax scooter you had for sale saying I was after a cheap hub and you assured me you was not giving it away and thing is I pay my way and offer help to many not to be scolded for nothing so if my face don't fit then neither does my nuts, torque arms or rims.

whereswally606   100 kW

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Re: A2B ultramotor axle size? and thread

Post by whereswally606 » Aug 19 2018 6:02pm

Ianhill wrote:
Aug 19 2018 3:15pm
I've got an a2b axle, nuts, torque arm, matching alex rim and spokes, I would give it away for free but I have asked about the lebowski board and got no where and ended up buying a inferior vesc,
I asked about an emax scooter you had for sale saying I was after a cheap hub and you assured me you was not giving it away and thing is I pay my way and offer help to many not to be scolded for nothing so if my face don't fit then neither does my nuts, torque arms or rims.
So when did you ask about a lebowski board?
Sorry if you felt I've scolded you?
I will say that I've been very busy with babies the last couple of years so my projects have taken a back seat. I remember one chap on the phone who responded to a gumtree ad I had going. That may possibly have been you I guess. All I remember about the conversation was that I wasn't happy selling a perfectly good road legal scooter for it to be made into something that wouldn't be able to be used legally on roads. If that was you Ian. I remember you being quite abrupt and rude about it. I totally agree that people can do whatever they want with something after they have bought it with their own money but it is my opinion that it doesn't help our planet to take working well built machines and turn then into projects.

Thanks to everyone for helping. I think I measured the threads to be 1.15mm but since that's not a real metric thread I can believe if mismeasured it.

Lastly Ian if that wasn't you on the phone then I apologise. If it was, well then I'm sorry you feel the need to be rude to strangers.

Regarding Lebowski boards I have a stock of the pcbs you can order the chip from Bas. It never earned me much doing the selling. I do it to ensure there was lower bar to entry to allow others to get a single pcb cheaper than ordering lots and having to find a home the the extras. So I think if you are blaming me for you not having a lebowski controller then it's odd because anyone has always had the access to gerbers, project files and lebowski himself. If you still want a through hole board then I can sell those, pm me. The surface mount stuff I haven't had a chance to work on. My second son is only 8.5 weeks old and the first is not yet 2.

Sorry to make this so OT not my intention.
Again thanks for the help chaps
Distributing "Lebowski" FOC Controller PCB (Through hole) since 2016
Moped: Emax 110s 2009

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