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Cause of RS motherboard failure: the no-luck wheel.


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I’m not able to solidly follow the series of events and the issues that have arisen.

 Either way, in case you removed the motor covers, the rim and the stairs need to be perfectly aligned when putting the motor covers back. They are in charge of keeping the magnets and the coils of the motor separated and aligned.

If you have caused a short in the motor by assembling the motor covers without aligning the rim properly, it could fry the control board.

 The rim and the motor covers are made of aluminium, which as a material is not able to store tensions like that. If you indeed did change the bearings, there are several steps that could’ve gone wrong in their assembly as well.

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The motor is almost certainly not to blame. To convince yourself- The motor should spin freely when the phase wires are open-circuit. You should feel notable resistance spinning the motor

Haha. I was sure they were not. But my cobbled together spacer with a zip tie came out. (I picked a stupid time to have apparently ran out of tape...) Yes, two were, and now I don't feel so smart... I

Just as an update- you were correct. It hit failure mode. So I put in all 5 jumper cables to make measuring the voltage easier. It was a consistant0 - 3.3 volts for each hall sensor as the wheel rotat

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The EUCBROS have a great assembly video after a bearing replacement. They tighten the motor covers in several torque sequences. They use blue locktite on the motor cover fasteners because over torquing them will strip the holes. The pedal hangers have to be level with each other so the shell clearance is good all around. I referenced their video for my bearing replacement. I also repacked the bearings with marine grease. I have over 700 miles with no issues since reassembly. I used my euc stand to level my pedal hangers.

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1 hour ago, Unipilot69 said:

The EUCBROS have a great assembly video after a bearing replacement. They tighten the motor covers in several torque sequences. They use blue locktite on the motor cover fasteners because over torquing them will strip the holes. The pedal hangers have to be level with each other so the shell clearance is good all around. I referenced their video for my bearing replacement. I also repacked the bearings with marine grease. I have over 700 miles with no issues since reassembly. I used my euc stand to level my pedal hangers.

Thanks, I did watch that as well. Great video to get a feel of what you are facing taking it apart...

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Posted (edited)
13 hours ago, mrelwood said:

The rim and the motor covers are made of aluminium, which as a material is not able to store tensions like that. If you indeed did change the bearings, there are several steps that could’ve gone wrong in their assembly as well.

Thanks. I suppose that is true with the aluminum. I'm pretty much down to grasping at straws for a a reason for this whole thing. I've also kind of lost track of the issues and the order that they came up. I do know that this whole thing started when I decided to put a knobby tire on the RS. I still don't know how a simple tire change lead to where I am. But at this point, there does not appear to be much sense in asking that question...

 

 

They were aligned fine. A motor shop that does motors for everybody from Toyota, crown and tennant to oilfield rebuilds changed out the bearing for me while it was there... The thing is that it makes that "grinding" sound even when the wheel is not spinning at all. So it almost has to be electric. No sound when you spin the wheel by hand. No noise / feeling of anything being wrong when you roll it with no power. As soon as you turn it on and try to balance it even with no movement at all, grinding and whinging.

 

Anyhow, I really don't know what options there are aside from a new motor. If a new board has the wheel whinging like this, it almost has to be the motor. There are not may other components (aside from the hall sensors that appear to be good.) 

 

*I've also lost track of what has been posted. But here is the wheel "grinding" as soon as it is powered up with absolutely no movement. At least that part does not appear to be alignment. I did also take it back out of the shell and the covers are still bolted down firm, in the orientation that they came off in, no gaps, nothing to indicate any problems. I will probably take it apart completely one last time before giving up... Maybe there is something that I have overlooked...

 

 

Edited by DWOTR
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15 hours ago, DWOTR said:

But here is the wheel "grinding" as soon as it is powered up with absolutely no movement.

This symptom alone could be caused by a stuck tire/motor, or a shortcut in the motor. Badly aligned motor covers could do that.

If both motor covers were off at the same time, the incredibly strong magnets will pull the rim into an angle. Simply assembling the motor covers back on will not align the rim.

 But you are right, if there’s nothing you can see wrong with the motor assembly when disassembling, and it makes a sound like that, a new motor seems to be the only way forward.

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21 minutes ago, mrelwood said:

If both motor covers were off at the same time, the incredibly strong magnets will pull the rim into an angle. Simply assembling the motor covers back on will not align the rim.

Hmm. Did you have another practical method in mind, for installing the covers while keeping the stator centered?

Thx

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7 hours ago, RagingGrandpa said:

Hmm. Did you have another practical method in mind, for installing the covers while keeping the stator centered?

Thx

I try to avoid getting both motor covers off at the same time. But if it can’t be avoided, you can center the rim with regular game cards (from a deck of cards) evenly laid out around the wheel:

- First try two cards on top of each other at noon, 3, 6, and 9 o’clock positions. Make sure the cards reach the other edge of the magnet, but not coming out from the other side.

- Add a card per pile until they no longer fit. Remove cards to make the piles even height, if necessary.

- Make sure the bearing is as deep in the motor cover as possible. Carefully hammer it in all the way if necessary, using a block of wood in between.

- Fix the stator onto a vice, cards pointing down.

- Install the motor cover as far as it goes by hand. If any edge of the cover remains higher than the rest, push from that part to make it even.

- Using the block of wood on top of the bearing area, carefully start hammering the motor cover in, little by little, always at the highest point.

- Try to rotate the motor cover every now and then. When it’s getting close to not being able to rotate anymore, rotate it to a position where the bolt holes align the best.

- Continue hammering until the motor cover is all the way in. Once done, go through an extra round just in case.

- Screw in the motor cover bolts so that the bolt heads do not yet touch the cover. Go through the seam between the cover and the rim to make sure the gap is the same size throughout the edge.

- Tighten the bolts so that they just barely touch the cover. Start going through the bolts in a star formation, tightening only a little at a time. Once all bolts are sufficiently tight, check that there is no gap anywhere between the cover and the rim. Then go through all of them once more.

- Turn the motor over on the vice, and remove the cards. Do not tilt the rim in relation to the stator, as it will easily tilt and start pulling out the bearing.

- Slowly rotate the rim to a spot where the gap between the stator and the magnets is as even as possible all around the perimeter.

- Install the second motor cover the same way you did the first one.

- After both covers are installed, I like to go around both bearings once more, hammering them all the way in with a block of wood in between.

- Check that the rim runs straight as you rotate it by hand.

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It's a complete shot in the dark, but are there any cracks in the plastic around where the L hangers mount to the shell? Even just a couple of very thin cracks can cause a mechanical disconnection between the motor and the board and thus cause vibrations. I had this problem on my 14s and I initially thought it was the motor or the board. This could also happen if the motor or board are not mounted tightly to the shell. My 14s's vibrations were more violent and less buzzy than what you have, but it could be worth checking anyways. Did it buzz like this before you opened it up?

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Posted (edited)
1 hour ago, mrelwood said:

I try to avoid getting both motor covers off at the same time. But if it can’t be avoided, you can center the rim with regular game cards (from a deck of cards) evenly laid out around the wheel:

- First try two cards on top of each other at noon, 3, 6, and 9 o’clock positions. Make sure the cards reach the other edge of the magnet, but not coming out from the other side.

- Add a card per pile until they no longer fit. Remove cards to make the piles even height, if necessary.

- Make sure the bearing is as deep in the motor cover as possible. Carefully hammer it in all the way if necessary, using a block of wood in between.

- Fix the stator onto a vice, cards pointing down.

- Install the motor cover as far as it goes by hand. If any edge of the cover remains higher than the rest, push from that part to make it even.

- Using the block of wood on top of the bearing area, carefully start hammering the motor cover in, little by little, always at the highest point.

- Try to rotate the motor cover every now and then. When it’s getting close to not being able to rotate anymore, rotate it to a position where the bolt holes align the best.

- Continue hammering until the motor cover is all the way in. Once done, go through an extra round just in case.

- Screw in the motor cover bolts so that the bolt heads do not yet touch the cover. Go through the seam between the cover and the rim to make sure the gap is the same size throughout the edge.

- Tighten the bolts so that they just barely touch the cover. Start going through the bolts in a star formation, tightening only a little at a time. Once all bolts are sufficiently tight, check that there is no gap anywhere between the cover and the rim. Then go through all of them once more.

- Turn the motor over on the vice, and remove the cards. Do not tilt the rim in relation to the stator, as it will easily tilt and start pulling out the bearing.

- Slowly rotate the rim to a spot where the gap between the stator and the magnets is as even as possible all around the perimeter.

- Install the second motor cover the same way you did the first one.

- After both covers are installed, I like to go around both bearings once more, hammering them all the way in with a block of wood in between.

- Check that the rim runs straight as you rotate it by hand.

I will break down this evening and will check it out. I would like to believe that it was assembled correctly- I have used the same shop for a decade now with no problems from a complete rebuild on a 250HP motor to a tiny steering motor. But there is always a first time- and I'm sure that this was the first EUC motor he would have seen.

 

Just the same, I am still holding out hope. This is a very useful guide and should be stickied somewhere. I will follow it step by step (probably bring the unicycle back to work where I have a little more bench space...) Good thing I have a million old decks of cards. 

 

*Edit: I just really want to thank you again for not only that post, but your support and help through this whole process. 

Edited by DWOTR
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6 minutes ago, Menace said:

It's a complete shot in the dark, but are there any cracks in the plastic around where the L hangers mount to the shell? Even just a couple of very thin cracks can cause a mechanical disconnection between the motor and the board and thus cause vibrations. I had this problem on my 14s and I initially thought it was the motor or the board. This could also happen if the motor or board are not mounted tightly to the shell. My 14s's vibrations were more violent and less buzzy than what you have, but it could be worth checking anyways. Did it buzz like this before you opened it up?

Thanks- I will check. It did not buzz before being opened. There was bearing noise developing- but nothing like this. But when I took off the shell, a couple of the pedal hanger bolts had been put in cross threaded (one head snapped off when taking it out- another one or two were almost impossible to get out without that problem...) I will check it out.

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2 minutes ago, DWOTR said:

It did not buzz before being opened

The outer shell provides structural rigidity as well, so removing the outer shell could have removed the last bit of structrual ridgidity needed. It was like this for me, my 14s only started vibrating after I opened the wheel to clean some dirt out of the trolley and I turned it on while open. It is easy enough to put the outer shell of the RS back on real quick, maybe try that as well, even if you don't see any cracks. Good luck.

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  • 3 weeks later...
Posted (edited)

I may as well give what should be a final update to this...

 

I actually finally got around to deciding I was going to bite the bullet and take the thing apart (again.) Life got in my way for the last few weeks. When I went to remove the shell, I noted on the side that had the pedal hanger problem that I had two of the bolts a tiny bit lose. I think I mentioned it earlier in the thread- but the pedal hangers were crossthreaded from the factory to the point that one of the bolts snapped while being removed, and two of them took the threads with them when I got them out. So I didn't want to over tighten what little was left holding on the shell.

 

Ironically, one of the bolts that I tightened tonight (it was one of the ones that took lots of the thread with it) striped out. So now the shell is held on by three bolts total on the one side.

 

Long story short- after reefing down on the ones left, it is not an issue. I will be ordering new hangers (or possibly checking if I can get them under warranty being as there is no reason for a bolt to break coming out the first time you take things apart- and I know I had sent pictures in an email long ago.)

 

So, thanks to everybody for their help. And I honestly hope this thread helps somebody searching the internet in the future. There was lots of very useful information provided by the members in the search for an answer... The last thing left for me it to remember to patch that new hole under the main board that I had to open up to get the black board to fit, and to splice a few inches of wire in the headlight wires for length...

Edited by DWOTR
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