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| The Xiongda motor unit, out of the hub, with the nylon sun gear visible on top |
Xiongda breakdowns
It seems clear the Xiongda 2-speed motor is a somewhat more fragile unit than the standard simple geared hub motor (e.g. the Bafang). We have 4 Xiongda 2-speed motors in our family, amongst the bikes we depend on for day-to-day transport up and down and around the mountain. All have required repairs. One has done over 10,000km and is on its 3rd nylon sun gear. The others have had the nylon sun gear replaced and one has also had the nylon planet gears replaced. One has had the motor magnets coming unglued. All breakdowns have been mechanical, not electrical. All breakdowns have been repaired in our workshop, without cost, although I expect over the long term we will need to keep replacing nylon gears at our own cost (a very cheap repair).
I consider this weakness to be well worth living with, considering the excellent characteristics of the Xiongda 2-speed, for our mountain riding conditions, and their low cost. I also expect Xiongda will resolve their problems with improved materials.
It's also worth considering that nylon gears in any geared hub motor have a limited life in heavy climbing (see my post about replacing Bafang planet gears). My Bafang SWXB did 7000km of mountain riding before needing new gears, and our Xiongda 2-speeds have done over 4000km on one sun gear so far. Changing nylon gears is a cheap and easy service to do occasionally for the tremendous benefits we get from geared hub motors.
It's also worth considering that nylon gears in any geared hub motor have a limited life in heavy climbing (see my post about replacing Bafang planet gears). My Bafang SWXB did 7000km of mountain riding before needing new gears, and our Xiongda 2-speeds have done over 4000km on one sun gear so far. Changing nylon gears is a cheap and easy service to do occasionally for the tremendous benefits we get from geared hub motors.
Failure of the nylon sun gear
The most common problem seems to be failure of the nylon sun gear in the hub motor. This is what both of our motors have had. One failed in less than 1000km, due to a known quality control problem in that batch of nylon castings – there were clearly visible gas bubbles. The other went to nearly 4000km before breakage, attributed to not having the optimal material.
The nylon sun gear transmits power in high gear - low gear power goes thru the nylon ring gear which surrounds the sun gear. For a video explanation of how the Xiongda gears work, see my youtube video here.
The nylon sun gear transmits power in high gear - low gear power goes thru the nylon ring gear which surrounds the sun gear. For a video explanation of how the Xiongda gears work, see my youtube video here.
How breakdown happens
When my front wheel motor failed, I was travelling slowly uphill and suddenly the wheel completely locked up. When I tried pushing the bike along, the main hub started unscrewing from the clutch plate (the right hand end of the motor, which screws in with a RH thread). This was troublesome but made opening the motor very easy. On opening up, we could see that the nylon sun gear had broken into large pieces which jammed other gears. This could have been dangerous at speed.
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| My front motor with shattered nylon sun gear |
When my son’s rear motor failed, the motor still freewheeled, and even ran roughly in low gear. This was because only the teeth had broken on the nylon sun gear, and only small pieces were free inside the hub. On opening, it became clear it wasn’t a good idea to run the motor after breakdown, as the small nylon gear pieces were jammed into other gears, particularly the nylon ring gear and its steel planets. Overall it was a much safer way to fail.
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| Rear motor with broken teeth on sun gear |
Another sun gear failure option: broken TIG welds
More recently, I had a new motor (less than 1000 km) fail by a breakage in the sun gear unit. This was a new model (2017) sun gear, with stronger nylon material. The nylon had no damage, but the steel internal lining of the nylon came unstuck from the steel boss.
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| Here's the sun gear lifted out of the motor, steel boss on top |
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| Here's the 2017 improved model sun gear the other way up. This is a failed one, where the nylon unit hs come unstuck from the steel boss. See the short runs of (what looks like) TIG welding between the nylon gear + steel liner unit, and the steel boss (with bearings pressed inside). |
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| With the steel boss in the vice, I can twist the nylon gear with steel liner around on the boss. That's because the little TIG welds have broken, and that's why the motor can't drive in high gear with this broken sun gear. |
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| The nylon gear with steel liner could be knocked off - it should be permanently stuck on |
I repaired this unit by simply replacing the sun gear. However I'm sure I can repair the failed sun gear somehow, perhaps with some sort of key between gear and boss - later.
Service from Xiongda
Bonnie at Xiongda has provided excellent service in response to breakdowns, with parts arriving in under a week.
Repairing the gears
If your Xiongda motor has failed only because of the nylon sun gear, repair is quite easy. All you need to do is remove the wheel nuts and washers on the chain (right hand) side, remove the sprocket cluster (on rear wheels), unscrew the side plate clutch unit, lift out the broken nylon sun gear, put a good one back in, then screw the side plate back on. Most of the motor can remain in the hub while the repair is done.
After removing the wheel from the bike and removing the sprocket cluster, the first step is unscrewing the side plate clutch unit. This threads into the RH side of the motor with a RH thread.
After removing the wheel from the bike and removing the sprocket cluster, the first step is unscrewing the side plate clutch unit. This threads into the RH side of the motor with a RH thread.
On the front motor this was easy. The jamming motor unscrewed the clutch mostly, so I only had to spin it off by hand after removing nuts and washers.
The rear motor was hard to unscrew. This is not surprising as the thread is tightened by both the motor torque and the pedalling torque through the cluster. We made a tool to bolt on, but the clutch unit was so tight I was worried we would break or strip the 2 M5 bolts.
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| Home made tool to turn clutch unit |
We poured boiling water on the main hub (tilting it to avoid any water on the bearings or wires) to expand it, and eventually moderate force cracked the clutch loose.
This youku video shows a charmingly easy unscrewing of the clutch unit, presumably by a Xiongda technician.
The nylon sun gear is front and centre of the motor after removal of the clutch unit. Levering it up with a pair of screwdrivers easily lifts it out of place.
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| Lifting out the sun gear |
Make sure to remove all pieces of broken gear from inside the motor. I used a scriber to scratch any pieces from between the teeth of the ring gear and the steel spur gears – there were a few pieces hiding in the sticky grease.
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| Here is the broken nylon sun gear lifted out of its place |
The replacement nylon sun gear easily slips into place.
Take care about removing the steel gear plate (and opening the inner planetary gear set), as there are only certain positions that enable all gears to mesh. There are often pen marks on the steel planet gears which need to be all facing inwards – I have centre-punched these marks on some of my gears to be more durable. Here is a youku video of a Xiongda motor being opened and the gear plate being taken off (and an impressive display of concrete quality).
There is much discussion on Endless-sphere about how best to lubricate these motors. I don’t have any clear conclusions currently. I haven’t been able to import any of the grease recommended by Xiongda, as it is not able to be transported by air. Some people use liquid lubricants in the motor, which makes sense, but isn’t explicitly supported by Xiongda. I’ve run 2 motors with automatic transmission fluid (ATF) in the motor for a couple of years now: it makes the motor run quieter, I think they run cooler, but they can drip a little oil out along the axle, especially if the bike is left lying on its side. Certainly the motors haven't come to harm from using ATF - although the ATF may have contributed to my slipping magnets problem.
Xiongda repair videos on Youku:
Opening the motor case:http://v.youku.com/v_show/id_XMTM2NjA3NjY4NA==.html?from=y1.7-1.2
Taking off the freewheel unit:
http://v.youku.com/v_show/id_XMTM2NjA1Nzg5Mg==.html?firsttime=0&from=y1.4-2
Replacing the nylon sun gear:
http://v.youku.com/v_show/id_XMTUzODg1NzI4MA==.html?from=y1.2-1-176.3.7-1.1-1-1-6-0
Main page:
http://i.youku.com/u/UNjAzODA3MzUy
Hi Bruce - Do you have contact details for Xiongda?
ReplyDeleteEmail Bonnie Xiong at:
DeleteBonnie at xiongdamotor.com.cn
what is the price with shipping when buying these from china?
ReplyDeleteHi Bruce, not sure if you are still following these comments. Thinking about getting the Xiongda motor. Still recommended? Also, I can see that the ATF can help cool the motor, but does the ATF induce drag inside the motor? Getting a motor in the current environment may be a bit sketchy. I've emailed Bonnie, so will see what the situation is. I have enjoyed reading parts of your blog! Has been informative.
ReplyDeleteHi Freddy, I still recommend the Xiongda - all our XD motors are still running well - but it's important to be able to do repairs if required. Not all people are up for fixing things! But we would all do well to get better at it. I don't notice any drag from the ATF - it's only a small amount in the motor case. I'm hoping we can still import Chinese stuff while they recover from corona virus - that's where we get all our bike and chainsaw parts!
DeleteHello Bruce, my name is tim and after reading your articles i bought one of these motors last year. i have followed both your articles and you have been very helpful. i run this motor on the front with a mid drive pushing the back. i only use it off road on a fat tire cargo bike. it is an exceptional motor. i have it wired with out a display by shorting the two wires on the controller and i have no PAS just throttle. my question is do you know if all i want is low range and more power just at slow speeds could i run a different controller with out the high/low auto switch and strictly run it in reverse with say 25 amp controller 48 volts? you are the only one i thought might know enough about this motor to answer? thank you for all your information it has been terrific nice job sincerely tim wood
ReplyDeleteHi Tim, I’ve often daydreamed about using 2 motors on a bike, I’m impressed you’ve made it work.
DeleteMy understanding of your idea is in 2 parts.
Firstly: using a normal single speed controller to drive an XD 2speed motor. I’ve also wondered about this but never tried. I expect a sensored or sensorless controller would drive the XD, once you work out the arrangement of the wires to get the rotation you want. A sensorless controller would make this easier - I’ve used many generic sensorless controllers from Greenbikekit.com with no problems.
The second question is how the XD would go with 25A and 48V. You’d be aware that voltage determines speed and current determines torque, so 48V would increase the speed of the motor by about 1/3 compared to the designed 36V speed - this may not help with your situation. 25A would be a high current for a little motor like this, so I’d be worried about overheating, especially at low speeds. I’d also be thinking about stressing the mechanics of the motor with more power. The problems I’ve had with the nylon sun gear shouldn’t apply to a motor run permanently in low gear - the nylon sun gear is used for high speed.
Re overheating: XD will include a temperature sensor in the motor as an option. The KT controller and LCD can read the temp but we’ve found the motors with temp sensors get confused about their speed and distance readings on the LCD. I’m sure the temp sensor could be read some other way. I find XD motors can overheat on long slow climbs: I’ve had 135C on an off-road mountain climb with very slow, very steep walking sections I sometimes do.
The good thing with XD is that if you do burn the windings, it’s relatively cheap to replace the windings as a spare part. This compares well with Bafang, who don’t seem to sell their armatures separately.
Good luck, let me know how you go. Bruce.
Thank you for replying to me Bruce your suspicions are correct as is your recommendation. sorry it took so long to reply Covid has affected me so much the last two years.
ReplyDeleteI figured I would just give you an update. I used another Bafang motor for the last couple years but still missed the torque of the XD Motor in low-speed situations. the mid drive i run is extremely low geared and will climb any hill I want by itself but when traction is needed is when I need the front wheel drive to help like in snow conditions and wet leaves. I bought a 30 amp Sensor less controller with Reverse I clipped all the wires I did not need inside the controller. I was going to use reverse if needed but wiring the phase wires only worked perfect first try and it is running in low range only like I wanted. It is very quiet and very powerful. I am running a 48 volt 350watt version of Xiongda It is a front motor I had them make the shaft to 135mm to fit my drop out. I ordered directly from them great experience. The controller now is very clean it has only battery power with an ignition switch wire for a simple on off then 3 throttle wires and the three phase wires. my controller is a 12 Mosfet controller with very heavy phase wires. I have upgraded the phase wires all the way into the motor to 12 gauge with only one heavy duty L10 water proof connecter. I was able to get the larger wires in thru the shaft with heat shrink around them because I did not need the hall sensors.
This step is to avoid melting of small phase wires i have had in the past at various connections between the controller and motor. This all works great now ,yes it could easily self destruct itself if I go heavy on the throttle for long time or on super steep hills but like I said my application is very specific. most days the hub is just along for a free wheeling ride its only when I hit a stretch of muddy ruts, slipper sandy hills or snow when I need the extra traction for very short periods of time. I feel I have fried enough wires and controllers in the past 5 years to know what I can and can not do With in reason. I am going to order an entire spare motor next to have on hand next for parts im sure ill need it. I will update you how long it last for my application. I will install a temp sensor eventually it would be really nice to know the temp but it is running at I am running ATF and have had no temperature problems on the factory controller. I Ran the factory controller at 52 volts for two years and never got anything close to hot. I am back to 48 volts yes this controller is double and the heat will build quick but in very very short usage I think ill be ok. Time will tell, someone has to push the limits so we can all learn as you have done. I realize I am asking a lot of this motor with 30 amps from a heat standpoint but with a LUNA ludicrous 30 amp 1700 watt BBSHD Pushing the bike at all times I'm not asking the front wheel to do much but turn a 26" wheel for a little extra traction. I will touch back with you at a later date. thanks you so much for all your information. it was exceptional and extremely helpful. If you have a recommendation on a way to install a simple temp sensor and read out with out using a std display please do share. it would be a nice piece of mind to look down at and know.
sincerely tim Wood
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