Dapu Motor Disassembly (Thread-on / Screw-on sidecover)

[amberwolf]

This is for a Dapu front geared hubmotor on a Pedego latch 2016, but it should work for any hubmotor whose sidecover as a whole unscrews (is not bolted on), and has the same ~70mm diameter spacing of the four tool notches on the non-brake side.


I was going to make a tool, but Cvin found an existing tool that works perfectly for it, for about $20, a GearWrench 4-wheel-drive spindle wrench, which uses a regular 1/2" drive socket wrench:

The only modification I would recommend is cutting a large notch halfway between two of the drive tips, to allow the motor cable to fit in it and not be damaged (in case you're opening the motor for some other reason than replacing that cable).


It's easier to use if you have a drive wrench on a T-bar, but any will do if you can apply enough vertical force on the tool to keep it in the cover notches while turning, and the wrench is long enough to give enough leverage. (I used one over a foot long) I recommend placing the whole wheel on a bucket, and leaning against the tire while hugging it to keep the rest of the wheel and motor case from turning while you unscrew the cover plate.


First you have to remove the lockring


then use the spindle wrench to turn it clockwise to unscrew it.



Broken cable (speed sensor wire), the reason for doing all this

and the extension cable i'll use to replace the cable with since the original is too short to pull thru the axle and splice, and the break is *at* the axle



Magnets in cover; there is only one in the six slots, so this is a 1-pole sensor system (rather than the six that are used on other such motors)

this is the sensor inside the motor




This all started because Cvin had a Pedego bike that was to be repaired by the local service center; the previous owner broke the system's speed sensor wire in the motor cable when taking the wheel off and putting it back on so it didn't read speed and thus wouldn't operate on PAS for more than a few seconds (throttle worked fine).

The repair center misdiagnosed the problem as the controller and so couldn't fix it, because they were trying to but unable to locate a controller (which wouldn't have fixed it) for a year.

It was very fast and easy for me to diagnose that it was the hubmotor, not the controller, simply by hooking up another Pedego hubmotor (from a second bike) with the same standard Julet connector, whcih then made this bike work, and then verifying the other was bad by hooking it up to the other working bike.... AFAIK they knew that the motor cable was damaged, but they didn't apparently realize that this is what broke the speed sensor.

 

[amberwolf]

Finally got to replace the cable; found that the white speedo wire was broken right at the edge of where it would go into the axle, and the torque washer design leaves a pointy thing right there as well, so it is possible that the wire was shorted to the frame thru the axle or washer. Can't tell now, though, but it did turn out that the sensor itself is actually dead (doesn't ground the signal output when a magnet passes it).

It was a surface mount sensor marked 4106x (see pic at end of post) and I didn't have one of those, but I took a similar sensor (thru-hole type, just like those used for typical motor halls) out of an old Fusin ebrake handle (they used switching halls rather than actual switches), as it was already pre-wired, making installation easier into this motor.

I apparently didn't get a pic of the final installation, but basically i took the SMT sensor off the board, and glued the thru-hole sensor over it's spot, large flat side down (angled side up). Because there is a capacitor right next to it, I coudln't put the leads the easy way out the end ofthe board, but had to put them toward and under hte motor windings (the Y-tie point is right there) and then the wires from it back around and under the windings again. Then they are routed over the board's edges and soldered to the board's 5v, ground, and signal pads.

Worked perfectly. BTW, this motor only uses one of the six magnet spots in the cover, so it uses a 1-pole rather than 6-pole speed signal.

 

[Oliv']

Hello Amberwolf,

I came to your post looking for replacement part for this cable, a phase is broken on mine..
Where did you found this extension cable? Or at least do you have a name or part number? I might not use the right keywords to find it...

Thanks

 

[amberwolf]

AFAICR, Cvin got one of these, or one like them:

https://www.amazon.com/eBike-Waterproof-Motor-Cable-250W/dp/B08YQYSD2F

https://www.amazon.com/BEISGUANGS-Electric-Connector-Extension-Accessories/dp/B09CTH182X

https://www.amazon.com/SCHUCK-Waterproof-Extension-Square-Conversion/dp/B08LQ78K9M?th=1&psc=1

I don't know which ones are better quality, or thicker phase wires, etc.

Grin Tech http://ebikes.ca may also carry them; theirs are probably good but the others may be the same stuff.

 

[Oliv']

Wow thanks! I am new to eBike and was not aware that it was kinda standard connector, your links helped me to find it in France in 5 min when I spent more than one hour before finding your post

Any advice to pass it inside the axle? Just add some soap water like ICTA sheath?

 

[amberwolf]

Any advice to pass it inside the axle? Just add some soap water like ICTA sheath?

It should go thru easily, as long as there is no previous silicone/etc in there, and the hole was machined properly.

If you have to use a lubricant, use some dielectric grease (the little packets they sell at automotive parts stores for battery terminals. Push just a little into the axle end hole without getting it on your fingers, and don't get it on the cable itself (it'll be hard to hold onto to push in if it or your fingers are all greasy). The reason to use this grease is it isn't conductive, but it is water-resistant, so it may help keep water out of your motor (via the axle entrance, anyway) too.

(soap attracts water, and has detergents that remove grease and/or oils that may protect your motor internals against rust, so you don't want that in there).


Just don't strip the outer jacket (just use the flat-cut end) until after you've got it thru the axle and in the motor. Also, if you are using the extension to replace the motor cable with, cut the cable as long as you can, like right at the base of the connector you are *not* using. Then, if you ever damage the cable at the axle exit (most common problem) you can probably have enough length to just feed more of it into the motor and redo the repair right then, without having to go get a new cable.

 

[Oliv']

Thanks! So I changed the cable and the motor is working well again
Having some spare length is appealing unfortunately the extension cable I got was almost the right length...so I'll change the cable again if it ever happens.

On my side after close inspection it was not broken at the axle exit but inside the connector, probably a cold solder joint between the pin and the wire:


Contrary to yours the wire path inside the axle is making a right angle so it might be more tricky to pass the new cable but you where right, it is not really difficult. Here are some pictures of my motor, if it can help others.
You can notice than all phase solders and part of the hall sensor wires are protected by a small plastic cover, be careful to not add any more width to the phase solder than original or it will be extremely difficult to put it back.



Last note if you are testing the hall sensors: on my motor the board silkscreen is wrong and mislead me to think that H2 is connected to H3...don't loose 5 min on this like me