Help with "damaged" 5000w hub motor

matt912836

100 W
Joined
Nov 25, 2012
Messages
122
Location
New York
Scored this motor and controller combo at what i'd consider a steal for just $75:


It's a 5000w hub motor laced to a 19" motorcycle rim. Very heavy, no distinct markings or model number. Svmc72080 controller



The only problem with it is there are 5 broken spokes and a sizable dent in the rim.



Is this rim salvageable? Replace the broken spokes, try to reverse the dents with the help of a vice grips/hammer, and tighten back all the spokes? A magnet doesnt stick to it so im assuming aluminum. Would it be usable with the dent? What's the best course of action for this rim?
 
Support the straight side of the rim in a block of soft wood, then use a mallet or nice smooth faced hammer to work the dented sidewall back in. You can probably save time by first squashing it flatter with a vise (with a wood block on the straight side then too).

You might screw it up or break it. But it's already screwed up, so what's the risk?
 
Chalo's right--no harm in trying--you can't make it much worse, and you can always replace it.

If it doesn't work or if it fails later, you can always replace it with a new rim of whatever size you need, along with new spokes. If you can get the same rim (or one with the same ERD/etc) you can just measure the existing spokes and get a new set of the same size. Otherwise just measure hte new rim once you get it, along with your motor's spoke flanges, and order new spokes that will fit the lacing pattern you choose.

Lacing a wheel is not hard, though it can take some practice. There's a bunch of threads (and sites) on lacing / building / truing wheels, if you have to replace the rim and want to try yourself.

I can't see the images (if you upload/attach them directly to the post, they'll show up for everybody) but I'll guess the rim is dented pretty badly? If it's a bad dent the tire bead wont' seat and the tube could pop out under it there, and get torn / pinched. If it's not too bad you can still use it but if it gets worse/cracks, it could do that anyway.

FWIW, if it's not a steel rim, there's a good chance that while bending it back will work, it'll crack where it's bent back and eventually split. That's what happened on my CrazyBike2's rear wheel:
https://endless-sphere.com/forums/viewtopic.php?f=2&t=12500&p=1229244&hilit=crack%2A+rim%2A#p1229244

First pic is from a while before the second, showing progression of the split.

file.php


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and in case the pic above doesn't show the problem well enough

file.php
 
I agree, nothing to lose, while you wait for the new rim and spokes to arrive.

You cannot run with 5 broken spokes at all though. DONT do that. Just remove the spokes, measure them, and get those coming right away. If you don't mind some wobble, the rim might be used for a shocking long time. Or it may crack when you bend it. Main thing though, is you do need the spokes.

Controller alone worth a lot more than the $75 I think. I have to wonder how that got done, car involved?
 
Use some heat on the rim to make it a bit more pliable and have less chance of a cold stress fracture and as mentioned a hard wood former that is a snug internal fit to the rim.
 
hemo said:
Use some heat on the rim to make it a bit more pliable and have less chance of a cold stress fracture

Heating aluminum over 300F or so weakens it permanently. Heating it enough to anneal it will typically reduce strength by 75% compared to its fully heat treated strength.

My advice is don't use heat. Just cold form it and see what you get.
 
You can make it rideable with a rubber mallet.
With such damage, it is unlikely that it is still round. Those rims are usually not worth riding less than perfectly true. I would relace a new rim.
 
Hugely appreciate everyone's input! took a shot in the dark and ordered some 128mm 10g spokes from Holmes hobbies, as those are for a cromotor in a 19" moped rim. I believe this is the same size as a cromotor and spokes are definitely thicker than the 12g spokes on my 1000w hub so 10g seemed right. They also come with the nipple. 19" tire and inner tube coming next, shinko 244? Then its a date with a hammer. Its going in an EEB frame, Mostly street riding with light offroading every now and then.

The only reason I picked it up was because it was such a great deal! As a 120~lb rider my 1000w hub motor in a 26" at 72v 20-40 amps had great acceleration especially once above 10-15mph and more than enough speed wise with a 40-45mph top speed. I do miss the torque from running a smaller diameter hub At lower speeds so I'm hoping to regain that sort of acceleration going higher wattage+more copper.

Besides, I'm starting to realize the 1000w motor just isn't up to handle my kind of riding. Even being such a light rider, by the time I ride the battery till its empty, the vented motor lets off a noticeable smell I can best describe as "hot and plasticy" :mrgreen: i opened the motor after a few of these rides to check on the windings theres surprisingly no marks of burning or charring windings everything still looks good but it's definitely hitting it's limit. My controller only pulls 40 amps when voltage drops to or below 72v so im only feeding it 3000w the most. It's said these motor saturate at 3500w but I already feel it getting somewhat sluggish when it's running hot at my power levels so rather than try to squeeze more power in this motor, add more copper instead. Plus shouldn't this motor feel a lot more powerful compared to the 1000w motor even at the same wattage? Is that noticable even with the added weight? Im Hoping I can gain some torque but limit the controller down to the same 40amps limit so I don't eat up range feeding it 80 amps.
 
Thicker spokes are almost always a worse choice. Spokes are springs. If you thicken them, they don't have as much elasticity and they don't work right.

The good news is that you're using a motorcycle rim that can take immense spoke tension. The bad news is that now you have to use immense tension or your wheel will loosen itself from just normal riding.
 
Anyone know where I can get an axle nut for this motor? It's missing one and it's not the same as the standard 1000w hub axle nut.
 
Since you don’t know the brand, it is a guess.
16mm 1.5 pitch I believe
But you can measure that

ps. A bigger motor won’t feel more powerful if you feed it the same power that you were feeding. In fact, according to various factors including wheel weight and phase impedance, it could feel less powerful. Anyway, if you are using a bigger motor and motorcycle wheel, it is making no sense not to feed it higher Amps.
 
A few whacks with a rubber mallet and I was able to close up the gap on the lip better than expected.

MadRhino said:
Since you don’t know the brand, it is a guess.
16mm 1.5 pitch I believe
But you can measure that

Grabbed a m16x1.5 nut from home Depot, perfect fit! Trued the rim as best as possible, definitely still a slight wobble but a world's difference from how I purchased it. And $75 for a 5000w kit Who can complain? Using motorcycle spoons made mounting the tire a lot easier and simple, I learned the hard way that sometimes its better having the right tools as I punctured the inner tube trying to pry the tire on with some screwdrivers :oops:


MadRhino said:
ps. A bigger motor won’t feel more powerful if you feed it the same power that you were feeding. In fact, according to various factors including wheel weight and phase impedance, it could feel less powerful. Anyway, if you are using a bigger motor and motorcycle wheel, it is making no sense not to feed it higher Amps.

I figured that, but also figured if I'm getting my 9c hub hot enough to release funny smells, I'm probably wasting a lot of power somewhere along the line. Yes, I'm putting on a heavier motor and tire, but this motor will never get remotely as hot as the 9c does, meaning it's a lot more efficient right? Which should translate to atleast some perceived power difference? My 9c definitely goes from feeling peppy to "rubberband-y" when it gets fed40 amps too long.

Well, I finally got this motor up and mounted, and I must respectfully disagree with this statement! Using the same exact controller, simply swapping motors, this motor feels atleast 50% stronger, at the same exact wattage my 9c was at! On the meter it's pulling the same wattage as before. I'm truly impressed at the difference! This 5000w motor on 20 amps feels like my 9c at 40 amps! I thought any increase that would be there would be negated by the heavier tire/motor/rim, yet it still feels WAY stronger with no added wattage. I know its about an inch smaller in diameter too so maybe thats contributing to it also. Gonna hold back on swapping controllers and see how this feels for now, plus trying to work out getting Bluetooth programming on the sabvoton before I do.

Here it is finally mounted on my bike:


photo upload internet
 
Many possible reasons for that. Your 9c motor might be a different winding, and/or maybe weakened by heat and wear. Could also be a loss in phase wires that were too small for the current that you were feeding...
 
Keep in mind that a wider stator/magnets (like the 5kw motor) gives more torque for the same conditions than a narrower setup (like the 9C), as the wider one has more active length of coil (vs end turns) to magnet than the narrower one.

I found that the X5304, for instance, had significantly more startup torque than the 9C 2807, using the same controller, in the same wheel/tire, on the SB Cruiser trike. Even once I had both on there at teh same time (one left rear wheel, the other right rear), with very similar 12FET controllers (same battery current limits, both generic controllers with I think the same MCU), I could test them at the same time and feel the higher pull of the X5304 side vs teh 9C 2807 side.

The HSR3548 also had a bit more torque than the same 9C, but not as much as the X5304. And the MXUS 3K's (4503 & 4504) had more than any of those (but the X5304 was pretty close).


Some simulator links to show what I mean:
x5304 vs 2807
http://www.ebikes.ca/tools/simulator.html?bopen=true&batt=cust_58_0.01_40&cont=C35&hp=0&wheel=20i&mass=170&frame=mountain&batt_b=cust_58_0.01_40&hp_b=0&frame_b=mountain&mass_b=170&cont_b=C35&motor_b=M2807&motor=M5304&axis=mph&wheel_b=20i

mxus 3k 4504 vs 2807
http://www.ebikes.ca/tools/simulator.html?bopen=true&batt=cust_58_0.01_40&cont=C35&hp=0&wheel=20i&mass=170&frame=mountain&batt_b=cust_58_0.01_40&hp_b=0&frame_b=mountain&mass_b=170&cont_b=C35&motor_b=M2807&motor=MX4504&axis=mph&wheel_b=20i

4503 vs 2807
http://www.ebikes.ca/tools/simulator.html?bopen=true&batt=cust_58_0.01_40&cont=C35&hp=0&wheel=20i&mass=170&frame=mountain&batt_b=cust_58_0.01_40&hp_b=0&frame_b=mountain&mass_b=170&cont_b=C35&motor_b=M2807&motor=MX4503&axis=mph&wheel_b=20i

hsr3548 vs 2807
http://www.ebikes.ca/tools/simulator.html?bopen=true&batt=cust_58_0.01_40&cont=C35&hp=0&wheel=20i&mass=170&frame=mountain&batt_b=cust_58_0.01_40&hp_b=0&frame_b=mountain&mass_b=170&cont_b=C35&motor_b=M2807&motor=M3548&axis=mph&wheel_b=20i

I'm not sure what the flat plateau of the 4503 and HSR3548 are at teh begnning, where they show the 2807 outperforming them in torque at first--that's not what I actually feel during startup from a complete stop. Maybe I have something else wrong in the simiulator setup (some things are guesses).
 
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