Converting a hubmotor to a middrivemotor

Discussions related to motors other than hub motors.
This includes R/C motors, botttom bracket, roller and geared drives.

Re: Converting a hubmotor to a middrivemotor

Postby crossbreak » Wed Dec 19, 2012 10:44 am

Hi Black Arrow,
this would be an expensive setup. A belt drive will weight more for the same power and it will be larger. Why do you want to throw away something that is already perfect?

If you dislike the clutch just weld it and use your own freewheel on the outside ;)

fechter wrote:It may be possible to remove the freewheel and flip it over and reinstall it to reverse its direction.

With my bafangs this is not possible. Also it would not make much sense, since then the heat sink would then be on the right, where space is already limited.
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Re: Converting a hubmotor to a middrivemotor

Postby Ariane » Wed Dec 19, 2012 11:35 am

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Re: Converting a hubmotor to a middrivemotor

Postby bØb » Wed Dec 19, 2012 11:53 am

BlackArrow wrote:Hi B0b,

Thank you I'm seriously thinking to uncork my Mac motor from its original planetary geared drive system.I will replace the sun gear on the MAC for belt gear to make something that look closer to the GNG drive system if the system box is open.

But with a more torquey belt for more power output that the gears can handle. This system will be in an enclosed box to protect it against debris, dust and water, to make at the end a silent, light and small mid-drive unit.

It's about the main idea I have in mind, good day!
Black Arrow


Hi BlackArrow,

I understand that you want to remove the planetary gear reduction from a MAC geared hub motor. If you would start another topic like "De-Gearing the MAC", I would be happy to share what would be a simple and killer method to do this. I just don't want to hijack this thread again. The resulting motor would be square (easy to mount) and at least 1-3/4" thinner than a MAC geared hub. Could even be air cooled if you want, since there are no gears to protect from grit. The motor would have only 1/5 the torque as a hub motor or 1/6 the torque of the hub motor converted to shaft drive. You would end up with a low~med speed high torque motor.

PC010438.JPG
This piece will run just like it is if you hook up the wires, controller and battery
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Re: Converting a hubmotor to a middrivemotor

Postby Ariane » Wed Dec 19, 2012 1:12 pm

.....
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Re: Converting a hubmotor to a middrivemotor

Postby crossbreak » Wed Dec 19, 2012 1:51 pm

The MAC will get horribly inefficient pushing more than 2000Watt input. Calculated a lot. This was on page 5 or so. The GNG has more power.Read the second post also
The only advantage I see is that it is narrow. With a belt on it is not narrow anymore. Planets are ~10mm wide belt would be at least 15mm :(

this is what my bike looks like ATM BTW, did not make any progress last sunday. next one i wont also, guess this will go on next year.
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Re: Converting a hubmotor to a middrivemotor

Postby Ariane » Wed Dec 19, 2012 2:30 pm

.....
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Re: Converting a hubmotor to a middrivemotor

Postby mr.electric » Wed Dec 19, 2012 4:18 pm

crossbreak wrote:
BTW, did not make any progress last sunday. next one i wont also, guess this will go on next year.

I am trying to be on the road before new years. Christmas parties , kids off school and family visits have made this an aggressive goal.
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Re: Converting a hubmotor to a middrivemotor

Postby StudEbiker » Wed Dec 19, 2012 6:15 pm

BlackArrow wrote:Hi Crossbreak,

I didn't bother you anymore :x :x i have erased my post, good day!
Black Arrow


Am I missing something, or are people being overly sensitive on this thread?? :?
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Re: Converting a hubmotor to a middrivemotor

Postby StudEbiker » Wed Dec 19, 2012 7:03 pm

I am attempting to remove the rotor from my Ezee motor and I want to make sure I'm doing this correctly. I searched high and low for pictures of doing this part correctly and couldn't find any.

Is this the way I am supposed to do it?

002.JPG
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003.JPG
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I put it on like this and tried some pressure, but it didn't come off "easy" like the gears did. Crossbreak warned in an earlier post not to force this so I want to make sure I am am correct before I apply any more pressure.
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Re: Converting a hubmotor to a middrivemotor

Postby fechter » Wed Dec 19, 2012 7:47 pm

That looks right. I think you need to remove a circlip from the rotor first though. Once you get the rotor about a cm past the stator, the force will be much less. It's easy to bend the rotor spokes. The magnets should be the only thing you're fighting against.
rotor clip.jpg
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Re: Converting a hubmotor to a middrivemotor

Postby bØb » Wed Dec 19, 2012 8:03 pm

I don't think I would proceed with the gear puller from what I can see. Can you post a wider shot of 003.jpg? You don't want to put any pressure on any of the magnets. You can pop them loose or chip them very easily. If you damage the coating on the magnets, they will corrode and fail. Is there a snap ring on the axle in front of the sun gear? The rotor that the magnets are glued into is not very stout and would be easy to bend. Why do you want to take it off?

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Re: Converting a hubmotor to a middrivemotor

Postby bØb » Wed Dec 19, 2012 8:17 pm

fechter wrote:That looks right. I think you need to remove a circlip from the rotor first though. Once you get the rotor about a cm past the stator, the force will be much less. It's easy to bend the rotor spokes. The magnets should be the only thing you're fighting against.
rotor clip.jpg


fechter,
You are looking at a different motor in the picture here. That is a picture of my MAC in my hand. Yes you do remove the circlip first :) After that I put a 1/2" nut on top of the shaft and put the cap back on with 2 screws to push the rotor off the stator a short distance to measure the thickness of the laminations. I never took the rotor all the way off. No need to.
I'm pretty sure StudEbiker's motor is different.

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Re: Converting a hubmotor to a middrivemotor

Postby StudEbiker » Wed Dec 19, 2012 8:18 pm

Well, it looks like I frocked this motor up! :oops:

Damn it!

Haste makes waste.

As for why I needed to take this off, I thought I need to do this to get the axle out to reduce it's diameter to turn freely.

Boy I'm pissed.

I saw no other clips on here (opposite side shown in pic7), so I still don't understand why this happened. :evil:
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Re: Converting a hubmotor to a middrivemotor

Postby StudEbiker » Wed Dec 19, 2012 8:22 pm

It seems like it may still be salvageable as it seems like the part with the magnets was only pressed onto the other part, but it still is upsetting. :(
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Re: Converting a hubmotor to a middrivemotor

Postby bØb » Wed Dec 19, 2012 8:42 pm

Can you turn the sun gear with your fingers?

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Re: Converting a hubmotor to a middrivemotor

Postby StudEbiker » Wed Dec 19, 2012 8:50 pm

Yes.
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Re: Converting a hubmotor to a middrivemotor

Postby bØb » Wed Dec 19, 2012 9:11 pm

OK. Under the hub (that is probably part of the sun gear) is that the outer race of a ball bearing I see in the picture? If so, I think the axle may push out of the stator holder from the opposite side.

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Re: Converting a hubmotor to a middrivemotor

Postby StudEbiker » Wed Dec 19, 2012 9:28 pm

I'm not quite getting what you're seeing. I don't see any outer races. There is a small gap between the ID of the sun gear and the OD of the axle, but I don't see anything that looks like it's part of a bearing. Obviously since the sun gear is spinning there's a bearing in there somewhere though. Here is a better picture.

008.JPG
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Re: Converting a hubmotor to a middrivemotor

Postby bØb » Wed Dec 19, 2012 10:42 pm

There has to be a bearing with it's outer race attached to the hub you pulled the stator off of. The hub and the sun gear are probably made from the same piece. The inner race of the bearing is on the axle. The stator carrier (aluminum piece with holes in it) is keyed and pressed onto the axle. If you press the axle from the side that you can see the key (the opposite side in your last picture) and support the stator carrier on the side shown in your last picture, it should come out of the stator carrier and have the bearing and hub still on the axle. There is also the possibility that the bearing inner race is around a tube attached to the hub and sun gear and the outer race is supported by the stator carrier. If it is you would press from the side in you picture and the axle would come out, leaving the sun gear, hub and stator carrier together. This is the best I can deduce from the pictures thus far. I only have experience disassembling a MAC. I think the motor crossbreak is using is more like yours than a MAC. After proof reading this I think the second method might be the best to try first if you don't get any information from crossbreak. You may be able to move the axle with a soft face mallet,just be sure to support only the stator carrier.

I think it is worth a try to press the rotor back on the hub. Just get it straight and use Red Locktite on it. I would help if you could put it in a Lathe or between V-blocks to track it straight.

The picture that fecther posted tonight with the note about the circlip is of my MAC motor. The bearing is between the sun gear built on the hollow tube and the stator carrier. You take the clip off and the only thing holding the stator is the magnets. The sungear/hub/tube is a slip fit to the bearing inner race. If you connected the wires , controller, battery and held the motor up by the hollow shaft, you could run it in your hand. This is why I think a MAC may be easier to convert than some others.

In a few days I am going to try to start a topic about MAC motor conversions and try to leave this thread to deal with bafang or similar motors. It is becoming confusing to follow :roll: bØb
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Re: Converting a hubmotor to a middrivemotor

Postby StudEbiker » Wed Dec 19, 2012 10:51 pm

Okay bob, I got the axle out. From by hitting the axle from the end opposite the sun. Thanks. :) Should the bearing on the sun gear feel completely smooth? This one has noticeable drag and rough spots.
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Re: Converting a hubmotor to a middrivemotor

Postby bØb » Wed Dec 19, 2012 10:59 pm

It should turn smooth. What kind of bearing is it?

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Re: Converting a hubmotor to a middrivemotor

Postby StudEbiker » Thu Dec 20, 2012 1:45 am

It looks like a sealed bearing.

011.JPG
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Re: Converting a hubmotor to a middrivemotor

Postby crossbreak » Thu Dec 20, 2012 4:53 am

hey StudEbiker,

hope your magnets took no damage :? Maybe the pics on page 8 shows the problem? Also this page here: http://www.ebikessf.com/disassembled-bmc-motor

Maybe one should not separate rotor and axle on a BMC when doing the conversion. I ask myself how ebikessf did. I have a guess, look at the pic below. This does not seem to be as simple as I thought.

Just for our interest: Now that you got the axle out already, can you pull off the bearing and hub? There can not be any hidden snap rings anymore I guess.

My bafangs seem to be different from both BMC and MAC :? if I remove the two outer snap rings, there is just the magnet force which holds the rotor on the axle. But you can not push out the axle if the sun gear and the rotor are not pulled off first, since there is a hidden snap ring between sungear and rotor. The sungear can be simply pulled off by hand.

All the best!
-cb
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Re: Converting a hubmotor to a middrivemotor

Postby StudEbiker » Thu Dec 20, 2012 11:42 am

I think the magnets are fine.

Yeah, it was that exact picture on ebikessf that I couldn't quite figure out what they were doing. I guess you have to support the stator through the openings in the rotor somehow and then pound out the axle from the side opposite the sun gear. So yeah, the rotor and axle will not separate on a conversion of an Ezee motor.

There is another snap ring on the back side of the hub that you can see in my last picture. I'm not sure what would happen if I take it out. I have just placed an order with ebikes.ca so I may contact them about getting another bearing for the hub as it seems like this one is not turning as smoothly as it should be and maybe I can find out from them about how to remove the hub from the axle, but as far as this type of conversion goes on an Ezee motor, removing the hub is not something you should normally need to do.

I think it is good that we are getting quite a few different types of motors in this one thread with the same goal in mind. And I like what you have done on page one showing a synopsis of what's been done "so far" as each of these motors seem to have slightly different designs, I think it's good to have them all in one place for anyone that is thinking about doing this in the future.

I am still very excited about this type of conversion and I appreciate your work developing this new type of drive! :D
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Re: Converting a hubmotor to a middrivemotor

Postby bØb » Thu Dec 20, 2012 11:45 am

StudEbiker wrote:It looks like a sealed bearing.

011.JPG


StudEbiker,

Sorry I missed this post last night. I checked several times for a new post and then retired to bed.

At this point, can you remove the key from the shaft, smooth any burrs and push the shaft from the bearing (left to right in .011.jpg)?
Has that snap ring in 001.jpg been rubbing on something?
Does the bearing feel dry when you rotate it? Heat from the stator could cook the lube out of the bearing. Especially if the motor had been overheated.
This is the "Achilles Heel" of geared hub motors: getting the heat out of the stator. I'm sure that not news to anyone though :|

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