Stand up faggio EV 3.7kw 16s

Lightweight / Folding / Portable EVs - seats optional
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Ianhill
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Re: Stand up faggio EV 3.7kw 16s

Post by Ianhill » Nov 01, 2016 3:34 pm

Fairplay to Amazon got a replacement set sent out within 24 hours and only wanted the faulty lever returned so ive got a full spare set all bar the rear lever thank you amazon and I will recommended these levers and to shop at amazon good customer service and second levers are perfect.

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Re: Stand up faggio EV 3.7kw 16s

Post by Ianhill » Nov 07, 2016 4:46 pm

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Before I started my rewind of this motor I wanted to understand its limits and its weak spots so I can come up with what I believe is the best way to add power.
The stator core seems to become saturated with eddy currents around 7000rpm or 1.05 khz for the inverter the motor will go faster but beyond this point massive heat will gather.
Reason
The laminates are broken into 9 sections in a circle that look like jigsaw pieces that link together to make a circle and then stacked. So there's small leakage phase to phase with the Separation in the laminate but the thickness in the stacking is not thin so large Eddy's circle and after 21khz under heavy load, break out and gather in the core so the leakage leaves a high hysteresis on each phase so when the opposite half of the wave is applied the first bit of energy is applied to the core to rectify the left over field and efficiency drops as well as the heat gather too.
The windings The windings used are multiple thin strand this in effect minimizes heat within the conductor like Eddy's lots of small path are better than one large, But controlling heat dissipation is impossible keep all strand touching the core so across the coil there will be hot spots and the end turns will get very hot as theres no core touching them only air which has very poor heat transfer property's, They have also used a plastic sleeve between the coils and core adding more thermal barrier to the copper I can understand they were trying to stop vibration damaging the enamel but plastic was not the best choice as a thermal conductive material.
Rotor The rotor is a laminate structure with a dovetail joint holding the magnets in again giving a path for eddy currents to get around the magnet and create heat within the rotor at high speed I'm not sure on what quality neodymium is used but Ive had it at 80°c with no noticeable torque loss so I'm assuming a n42 strength with no manufacturer markings.

How to improve
My plan is not to spin any faster but add more torque and make it faster through gearing. So I will rewind the motor with rectangular winding wire single core similar to below.
Edgewise_Coil_Square_634528376947358074_5.JPG
Edgewise_Coil_Square_634528376947358074_5.JPG (51.65 KiB) Viewed 1949 times
This way I can get the max amount of copper possible on each tooth and have good surface contact for heat dissipation, I will remove the plastic sleeve on each tooth and use a heat transferring epoxy to dip the finished stator in and then build up a thick layer around the end turns giving them a thermal path back to the the stator that's better than air. The can again is silver and smooth worst possible combination so I've seen a trick Tesla use to add fins within an extra can external of the motor for more heat conductive mass and channeled air flow across the fins helping massively to cool the motor I can not do this across the whole motor as it will not mount in the frame no more but I can pull it off on the section that contains the stator underneath I will keep the fins silver and spray both outer cans matt black.
Last edited by Ianhill on Nov 09, 2016 10:35 pm, edited 1 time in total.

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Re: Stand up faggio EV 3.7kw 16s

Post by Ianhill » Nov 08, 2016 2:35 am

stupid moment
Seems I've overlooked the most major aspect of the leakage, skin affect on the conductor/s and edge effect that comes Into play with high frequency switching exactly like what's going on in the motor, So the leakage is coming from the conductors and into the stator creating the Eddy's and heat in the first place doh.

So the square conductor is only rated to 400hz so ive looked at litz rectangle winding wire type 8 like below this is recommended to 10khz and would outperform the stock windings no doubt
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So I'm still very undecided and Still learning also so I will look into the highest frequency windings fit for purpose, I believe it will be ultrafine strands.

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Re: Stand up faggio EV 3.7kw 16s

Post by dventu » Nov 08, 2016 11:23 pm

How do you slip the coil out. Isn't it glued to the side. On a side note make sure your armature magnets arent cracked. I have a magnet cracked. It runs fine but the magnet chipped. I put glue on it until it explodes. I have another motor. [SMILING FACE WITH OPEN MOUTH AND TIGHTLY-CLOSED EYES]

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Re: Stand up faggio EV 3.7kw 16s

Post by Ianhill » Nov 09, 2016 12:55 am

New motor are you going to let's us know which one :?:

Yes the coil would have to be formed In the stator first never to come out, then epoxied in with a polyurethane and encapsulated on the end turn's, I think I will use this motor to learn as much as I can, I've learnt a lot without touching a turn of wire yet but ultimately I would like a nicer quality motor something with a sealed can low kV rating and high frequency capable, so it can be maintained better.

If you have cracked a magnet that would suggest its got mighty hot fast with some thermal shocking maybe even hot then cooled fast in cold climate ?, After striping my motor the front bearing was toast and the windings are very floaty and lose. I'm sure I can Improve it but it will never be a true turbo lump whooshing and poping with a screamer pipe on it so this is my practice run till I can get hold a motor more upmarket.
Ultimately I would like to use my electrical qualifications to get involved fault checking, refurbishing, and health checking any local industrial motors, I have found something I have a very high interest in, I've been bite and got the bug now.

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Re: Stand up faggio EV 3.7kw 16s

Post by Ianhill » Nov 09, 2016 10:34 pm

Another stupid moment

There's 6 commutation steps for one 360° electrical commutation, The controller is based on hall signalling measuring rotor angle to add negative and positive torque to the rotor, At a set speed around 30mph for myself the controller switches into top speed mode trigged by the halls frequency, Then it uses the microcontroller to calculate when the flux density reaches its peak threshold then applies switching and takes advantage of induction flyback (field Orient control)

The boo boo
Based on the info above and my 120° 9n6p motor I'm getting 9 pulses per 360° mechanical rotation, I get 7000rpm before I get major leakage so I have to multiply 7000rpm by 9 pulses for 63000hz but thats per minute, so for hz per second, of all 3 phases I got 1050hz per second at full speed not 21khz like a 200k rpm motor :oops:
On the flip side the litz type 8 is more than upto the job at 10khz its 9times overrated.

So a good point is to have good quality wire in the halls a multi strand sliver Teflon as theres over 1000hz on these at the point its switches from hall control.

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Re: Stand up faggio EV 3.7kw 16s

Post by dventu » Nov 10, 2016 4:23 pm

New motor is referring to a replacement but it the same style. Why not film the teardown of the coil and removal from the housing

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Re: Stand up faggio EV 3.7kw 16s

Post by dventu » Nov 10, 2016 4:24 pm

I find it strange the these scooter s have slotted axle points but they aren't using hub motors. Hmm got me thinking custom rim.

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Re: Stand up faggio EV 3.7kw 16s

Post by Ianhill » Nov 10, 2016 5:13 pm

dventu wrote:I find it strange the these scooter s have slotted axle points but they aren't using hub motors. Hmm got me thinking custom rim.

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These motors are inrunner so the magnets are internal of the coil so the can is stationary, if it was to spin the phase wire would wrap up and break off.
An outrunner has its magnets external of the coil so the can is rotating and the phase wires come out of the spindle/Axel.
Bonus of an outrunner is more magnet surface area for similar size design giving added torque but at the cost of heavier rotor weight. But a good inrunner will have a lighter rotor mass but less magnet area so it will spin up faster but with less torque.

Some outrunners are setup for hub use with two bearings the same size with an enclosed can and the wires come out of the axel, The RC type use a open can design with one small bearing on the output shaft side then a large bearing on the phase wire side so the wires can come out inside the large bearing, the RC type motors have lighter mass but I would have thought a enclosed hub type being equal both sides would give a better balanced rotor and bearings wear more identical.
For the cost and intended purpose the 48v 1600w is a good motor I find I like inrunner designs more myself I'm a fan of high rpm.

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Re: Stand up faggio EV 3.7kw 16s

Post by Ianhill » Nov 25, 2016 8:26 am

Well my season of blasting around is officially over, After a brush with death I'm lucky to be writing this post, high speed is fine when the weather is calm and on a nice straight but heavy winds + high speed cornering sent me massively wide on a bend narrowly missing parked cars, lucky there was no oncoming traffic the new brakes were worth every penny at that moment they saved my bacon got me slowed down enough to turn out of it, without them I be posting from A+E.
On the good side its max speed is 78kph I'm still waiting on my sprockets to squeeze it past 80kph I know it can do it if it was summer no wind nice day I'm sure with the sprockets I'd clear 50mph but I can not video it the footage is terrible I need a gopro my phone just goes bright and dark with wavey lines maybe I could do a drive by video when the winds calm.
Its running lovely at the moment I've put new bearings in the motor, the brakes do not rub one bit and the steering bearings feel a lot better its in tip top condition at the moment I'm very happy with the range its got 970wh capacity and will do between 20-30 miles maybe more maybe less depending on ambient etc, I average 30wh normally.

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Re: Stand up faggio EV 3.7kw 16s

Post by Keith_hill » Nov 27, 2016 1:18 pm

Forgive me if I've missed it, but do you have any videos of you riding your scooter?

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Re: Stand up faggio EV 3.7kw 16s

Post by Ianhill » Nov 27, 2016 2:31 pm

Keith_hill wrote:Forgive me if I've missed it, but do you have any videos of you riding your scooter?
https://youtu.be/puC6XQ9Kgus

That vid shows it running 2.8kw or 40mph in 12s lipo, its not the best of footage, I'm hoping tomorrow is nice enough to show it climb a few hills and top speed run at just over 3.6kw or near enough 50mph on 16s lipo, I'm struggling to get usable footage when going fast it just looks awful and not showing true representation of the speed.

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Re: Stand up faggio EV 3.7kw 16s

Post by Keith_hill » Nov 27, 2016 2:49 pm

Very cool! it looks nice and stable.
I hope you get a good day tomorrow to ride - and hopefully a video to go with!

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Re: Stand up faggio EV 3.7kw 16s

Post by Ianhill » Nov 28, 2016 12:41 pm

Top speed run 48.4mph

Short blast and overtake


Took the scooter for a short run today I only charged the cells to 3.95v I didn't want to be riding around for too long the sun was going down and the temps drop off fast. I got 48.4mph on the quick blast after the battery warmed up a bit.
I'm thinking of my next project now I want to go a fair bit faster I don't think a scooter can take me there so I'm going to use my solid tail mountain bike with triple tree forks remove the crank and pedals and replace with a boma motor rewired for lowered kV and encapsulated, 120v Bluetooth controller and 28s of 10000mah lipo still over 1kwh capacity, I'll aim for 7kw bursts and cruising speed of 30mph and top out over 60mph if the recipe is just rite.

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Re: Stand up faggio EV 3.7kw 16s

Post by ElectricGod » Dec 12, 2016 3:40 am

Ianhill wrote:Top speed run 48.4mph
Took the scooter for a short run today I only charged the cells to 3.95v I didn't want to be riding around for too long the sun was going down and the temps drop off fast. I got 48.4mph on the quick blast after the battery warmed up a bit.
I'm thinking of my next project now I want to go a fair bit faster I don't think a scooter can take me there so I'm going to use my solid tail mountain bike with triple tree forks remove the crank and pedals and replace with a boma motor rewired for lowered kV and encapsulated, 120v Bluetooth controller and 28s of 10000mah lipo still over 1kwh capacity, I'll aim for 7kw bursts and cruising speed of 30mph and top out over 60mph if the recipe is just rite.

Hey Ian...I didn't see you had a thread before...don't know why. Oh well.

Your scooter is coming along nicely. Nearly 50mph down hill...not bad. I was wondering why you didn't pass that car sooner. LOL. I don't think I would want to try for 60mph on those knobby tires, but on street tires...yeah for sure..oh wait...I have on a my scooter. On yours with those smaller tires...that might be really interesting. I'm expecting 50mph on my Currie on level ground with the 80-100 outrunner. Should be fun!

Regarding the BOMA, you can see part of why I didn't rewind the burned out one I have. I saw those jigsaw puzzle stators and thought that it would be a problem. I'll still rewind it...eventually and I'll use several 32 awg strands. My thinking is based on several things. Tiny strands are uber flexible so winding an inrunner should go easier with smaller awg wire. Also , the skin effect issue, but also, I should be able to get a bit more copper on each tooth since the wires will lay flatter.

Regarding your motor stutter issue...
I have 3 BOMA motors and never had that problem on my Kelly controller. I ran all of them on 82 volts so my RPMs were much higher than yours are at 60 volts. I think you have some other problem...like the controller is too slow to keep up or flaky halls or RF noise that is interfering with proper hall reading.

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Re: Stand up faggio EV 3.7kw 16s

Post by Ianhill » Dec 12, 2016 1:01 pm

ElectricGod wrote:
Ianhill wrote:Top speed run 48.4mph
Took the scooter for a short run today I only charged the cells to 3.95v I didn't want to be riding around for too long the sun was going down and the temps drop off fast. I got 48.4mph on the quick blast after the battery warmed up a bit.
I'm thinking of my next project now I want to go a fair bit faster I don't think a scooter can take me there so I'm going to use my solid tail mountain bike with triple tree forks remove the crank and pedals and replace with a boma motor rewired for lowered kV and encapsulated, 120v Bluetooth controller and 28s of 10000mah lipo still over 1kwh capacity, I'll aim for 7kw bursts and cruising speed of 30mph and top out over 60mph if the recipe is just rite.

Hey Ian...I didn't see you had a thread before...don't know why. Oh well.

Your scooter is coming along nicely. Nearly 50mph down hill...not bad. I was wondering why you didn't pass that car sooner. LOL. I don't think I would want to try for 60mph on those knobby tires, but on street tires...yeah for sure..oh wait...I have on a my scooter. On yours with those smaller tires...that might be really interesting. I'm expecting 50mph on my Currie on level ground with the 80-100 outrunner. Should be fun!

Regarding the BOMA, you can see part of why I didn't rewind the burned out one I have. I saw those jigsaw puzzle stators and thought that it would be a problem. I'll still rewind it...eventually and I'll use several 32 awg strands. My thinking is based on several things. Tiny strands are uber flexible so winding an inrunner should go easier with smaller awg wire. Also , the skin effect issue, but also, I should be able to get a bit more copper on each tooth since the wires will lay flatter.

Regarding your motor stutter issue...
I have 3 BOMA motors and never had that problem on my Kelly controller. I ran all of them on 82 volts so my RPMs were much higher than yours are at 60 volts. I think you have some other problem...like the controller is too slow to keep up or flaky halls or RF noise that is interfering with proper hall reading.
I've been here lerking I don't think many open the thread reading stand up faggio but there's nothing gay about it its a Grand theft auto thing.
I'll give it a blast at 84v soon with my new battery build, I've been cooking along at 67.2v and its plenty, at 84v I can use medium on controller and have say 3.2kw from the start no turbo to 3.7kw it would be more like 4.7kw on boost at 20s and it will melt the windings to bits, where as with 16s on high it starts at 2.8kw gets to 30mph or so then changes up to 3.7kw and the motor holds it as its already spinning in a efficient rpm at 20s it will start at 3.2kw and drop 4.7kw amps on a maxed out motor and I don't think it will go to well in the long run it will over heat.
I think its a little jerky being a cheap controller the motors halls etc work It spins down to 1mph or so but pulls of with a small leap when the controllers on max but it don't on med or low so I don't think there's a fault on my end and its really minor I'm being fussy.

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Re: Stand up faggio EV 3.7kw 16s

Post by ElectricGod » Dec 13, 2016 8:13 am

Your motor can handle it, just keep it cool. Remove those vent grills/covers on the end plates. In fact open them up more and then add a fan on the non-driven side so you can force air through the motor.

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Re: Stand up faggio EV 3.7kw 16s

Post by Ianhill » Dec 13, 2016 5:04 pm

ElectricGod wrote:Your motor can handle it, just keep it cool. Remove those vent grills/covers on the end plates. In fact open them up more and then add a fan on the non-driven side so you can force air through the motor.
Is someone trying to get me go boom :)
I've been thinking those end caps are restrictive on air flow I was going to mount a blower motor directly on the side of the motor sealed with the end cap so its sucking air from the cog side like u mentioned, other option is to seal the end caps and pump a coolant that wont corrode through it but all that will cost and I'm in half a mind on getting something with more kick and wound stock for my needs something like the big block in the 3-5kw range.

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Re: Stand up faggio EV 3.7kw 16s

Post by ElectricGod » Dec 13, 2016 5:55 pm

Ianhill wrote:
ElectricGod wrote:Your motor can handle it, just keep it cool. Remove those vent grills/covers on the end plates. In fact open them up more and then add a fan on the non-driven side so you can force air through the motor.
Is someone trying to get me go boom :)
I've been thinking those end caps are restrictive on air flow I was going to mount a blower motor directly on the side of the motor sealed with the end cap so its sucking air from the cog side like u mentioned, other option is to seal the end caps and pump a coolant that wont corrode through it but all that will cost and I'm in half a mind on getting something with more kick and wound stock for my needs something like the big block in the 3-5kw range.
The big block will definitely get you more power/speed...lots more...stunningly more. The big block is about the same length as the BOMA motors, but it's taller. In my scooter it just barely fit in the space.

Do you know what temps your motor runs at? Coolant has been discussed endlessly on ES. You would need a thin mineral oil and of course seal everything up. Sealing up the motor is pretty easy with a completely closed up inrunner. The general conclusion about using some kind of cooling fluid is that it adds internal resistance to motion that reduces motor efficiency significantly enough to not make it worth the trouble. If you could seal the stator from the armature, then it would be doable since the oil wouldn't create drag. After reading several lengthy discussions about motor cooling, that's why I went with a blower instead. Air adds no new drag that isn't already there.

BTW...I think the BOMA motors are wound as separate teeth and then assembled into a complete stator. I'm not sure how they do it, but since there are not multiple connections beyond the WYE connection, they obviously wind it with continuous strands.

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Re: Stand up faggio EV 3.7kw 16s

Post by Ianhill » Dec 13, 2016 6:48 pm

Are your 1500w and 2000w boma identical in dimensions?
Forced air is the easiest way of cooling for sure there's a 100mm 24v blower thats inlet matches the motor circumference and it would dump air down the rear of the scooter frame.
But nothing compensates for the extra magnet and tooth area of a bigger motor, the magnets in the boma are held in with a tongue and groove type affect with a pin to secure in place and a bit of tigerseal so there's a big weak spot where a magnet can fly off when spun fast and the end turns of the windings are just floating in the breeze.
I suppose I'm going to blow my motor soon i have a 1600w brand new only spun with no load to test at 48v and i have just serviced the motor that came fitted with the scooter, other than being dirty and the front bearing been toast its still not to bad shape the copper has darkened and hardened but its still got good resistance plenty of life left in it hopefully.

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Re: Stand up faggio EV 3.7kw 16s

Post by Ianhill » Dec 14, 2016 12:06 pm

Took the scooter down the shop for a blast and left it outside when I got on the motor was cold, i think the rotor shaft the sprocket mounts to was slipping but the rotor was spinning, I think its an interference fit ive never checked and when I pulled off there was a few Stutter's like the torque load was changing (slippage of the shaft then when it all warmed up I could fill throttle start again I suppose its from running it to hard and the hot cold cycles are taking its toll.

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Re: Stand up faggio EV 3.7kw 16s

Post by ElectricGod » Dec 14, 2016 12:16 pm

Ianhill wrote:Are your 1500w and 2000w boma identical in dimensions?
Forced air is the easiest way of cooling for sure there's a 100mm 24v blower thats inlet matches the motor circumference and it would dump air down the rear of the scooter frame.
But nothing compensates for the extra magnet and tooth area of a bigger motor, the magnets in the boma are held in with a tongue and groove type affect with a pin to secure in place and a bit of tigerseal so there's a big weak spot where a magnet can fly off when spun fast and the end turns of the windings are just floating in the breeze.
I suppose I'm going to blow my motor soon i have a 1600w brand new only spun with no load to test at 48v and i have just serviced the motor that came fitted with the scooter, other than being dirty and the front bearing been toast its still not to bad shape the copper has darkened and hardened but its still got good resistance plenty of life left in it hopefully.
The 1500 and 2000 watt motors look identical except the cable is larger. All dimensions are identical. The armature and stator are the same design, just a little longer in the 2000 watt version. The windings are done equally poorly as well. Same end caps and bearings too. They use the same sprockets, etc.

On any inrunner worth having the magnets are going to be glued in place. I was looking at a tear down of a larger and super cheap inrunner last week and that design had the magnets trapped inside the armature stack and as a result about 1/8" further away from the stator teeth. I guess it had one advantage...the magnets were just bar magnets rather than shaped to be cylindrical. It's my thinking that the gap between the magnets and the stator teeth is a bad thing. To maximize torque, the magnets need to be very close to the stator teeth. I'm sure it happens, but it must not be too much of an issue since all RC inrunners spin much faster than any EV inrunner and they mount the magnets with glue too. I think that a sufficiently good epoxy would be enough to keep the magnets from flying off. In the BOMA and big block they both use glue and dove tails to hold the magnets in place. Apparently it is "good enough". The BOMA motors are cheap inrunners. You can't really expect them to be stellar performers or to use hi-temp wire. I suspect you are running it close to it's maximum capability without forcing air into it. Most of that air is going to flow through the armature area since the windings are really tightly packed together. Same for the big block.

Image

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Re: Stand up faggio EV 3.7kw 16s

Post by ElectricGod » Dec 14, 2016 12:37 pm

Ianhill wrote:Took the scooter down the shop for a blast and left it outside when I got on the motor was cold, i think the rotor shaft the sprocket mounts to was slipping but the rotor was spinning, I think its an interference fit ive never checked and when I pulled off there was a few Stutter's like the torque load was changing (slippage of the shaft then when it all warmed up I could fill throttle start again I suppose its from running it to hard and the hot cold cycles are taking its toll.
That would be bad if it is slipping between the armature and the motor shaft. I have not had that issue on 3 BOMAs running them hard. The 2000 watt version uses the same motor shaft with slightly longer (1/4" longer?) magnets. I ran that motor the hardest and it never did anything like you are describing. I suggest trying a different motor controller. I suppose you could pull out the armature and try turning the armature on the shaft. If there is any movement at all, then yeah, that issue is only going to get worse if you don't do something about it. BTW...pressing the shaft into the armature is pretty typical assembly and doesn't fail very often. Just about any motor ever made has a pressed in shaft. In the big block, there is a key way in the shaft that the armature stack fits into. I have no idea about the BOMA motors.

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Re: Stand up faggio EV 3.7kw 16s

Post by Ianhill » Dec 14, 2016 1:58 pm

I figure this motor could fail by fatigue in the through bolts that are 5mm lol snaping but they are OK, and like mentioned the rotor playing up, I will try it again tomorrow see if I can repeat the fault when it warmed up it stopped and it must of slipped a few turns at most I except it will get worse with time specially in mild weather.
Lucky I have a spare motor, I'm unsure of the millage on this motor, but its covered 100 miles or so since I stripped it for service and it took one bearing and god knows how far the first owner of it took it but it was full of dust and dirt.
I'll have to keep an eye on it, it stopped soon enough when warm so its a cause for concern at the moment maybe lighter gearing help it out.

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Re: Stand up faggio EV 3.7kw 16s

Post by ElectricGod » Dec 14, 2016 6:37 pm

Ianhill wrote:I figure this motor could fail by fatigue in the through bolts that are 5mm lol snaping but they are OK, and like mentioned the rotor playing up, I will try it again tomorrow see if I can repeat the fault when it warmed up it stopped and it must of slipped a few turns at most I except it will get worse with time specially in mild weather.
Lucky I have a spare motor, I'm unsure of the millage on this motor, but its covered 100 miles or so since I stripped it for service and it took one bearing and god knows how far the first owner of it took it but it was full of dust and dirt.
I'll have to keep an eye on it, it stopped soon enough when warm so its a cause for concern at the moment maybe lighter gearing help it out.

For example, If you are running at 5:1 now and go to 6:1, that will ease up the load on the motor shaft...if that's the problem, but you will have a lower top speed.

Slipping a few turns...even one...doubtful. How "Warm" do you think the motor got in the few seconds it stuttered that it would cause sufficient expansion in the armature to seize up on the shaft? I had an RC car some time ago that would not hold it's driver sprocket very well, The flat on the motor shaft was plenty big, but the set screw was some kind of soft steel. I think it never got hardened. Anyway, it went from racing around to free spinning in an instant. There was no sound or performance difference before it failed. One second it was rolling around and the next it wasn't. I filed the set screw flat and retitghtened it. I went back to zipping around and a few minutes later...same thing. Once it had spun, there was no waiting or sitting or warming up and then it would work again. I'm just saying that if your motor shaft had spun in the armature, then you wouldn't be going anywhere after that. There's a lot of torque getting applied to that 10mm motor shaft. There's little chance that it's going to spin and then catch and then not spin again almost immediately.

I have my 2000 watt BOMA all taken apart. I can look at the armature tonight and post pics of it. That will be definitive if it can spin or not.

Through bolt fatigue. The bolts just hold the end caps in place and clamped to the motor can. It's friction between the end caps and the can that keep most of the turning from happening between the parts. Does your motor mount by a bracket welded onto the can or via the end plates? If there's a bracket welded to the can, the torque on the end plates is only whatever is required to overcome bearing friction. If you bolt to the end caps, then it's friction between the can and end caps that resists 95% of the rotational torque. Those through bolts are just holding the end caps in place. If you are worried about slippage between the end caps and the can, just mark the joint between them in a couple of places with a sharpy. If they are sliding or shifting, the mark across the joint will move out of alignment.

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