Introduction: Mounting Hoverboard Wheels Securely and Easily Onto Stateboard/Longboard Trucks
Hoverboard wheels are great. They are inexpensive (~$25 shipped for 6.5" variant) and provide ample power for many robotic applications, and even human-moving applications. The trouble about utilizing these in an electric longboard is the wheel mounting.
I have been wanting to build an electric longboard using these wheels for quite some time, and I am certainly not the only one. After a brief google search, you can find eboard forums where people have been attempting to use these motors for ~2 years now for eboard builds. Infact, a few people have successfully used these motors in their build. But, when you see how they did it, it certainly doesn't come off as 'secure' or safe. I believe this has pushed off most people from trying to use them.
As far as I can tell, I believe i'm the first person to modify these wheels in this way which provides a very secure and sleek mount solution to conventional longboard/skateboard trucks. I have been using this exact motor mounting on my current eboard for the past few months without any signs of stress or loosening, and as such I believe it is reliable and ready to be shared for others to utilize.
Some of the pictures are from my current, already modified, hoverboard motors which are the 6.5" variant. This instructable will demonstrate the modifications being done to a new truck and motors for the 8" variant.
There are 3 wheel sizes i'm aware of that were made for hoverboards. These modifications will work for ALL hoverboard wheels, as the shaft and cores are all identical between the types.
6.5" - Most common and widely available. Very cheap at ~$25 shipped in USA
8" - Second most common, reasonable availability. Fairly inexpensive at ~$35-45 shipped in USA
10" pneumatic air tires - Very rare. Don't have any but would be awesome for many applications. Expensive at ~$100 shipped from China
This method of mounting requires no expensive tools, only some fairly basic equipment. No Lathe or Mill needed!
Supplies
I have kept the supplies down the basics to make this accessible to as many people as possible. You will likely already have many or all of these tools.
Basic Required Tools:
- A 5/16"-24 TPI Tap & Die (This is a very common thread which is found in most all Tap & Die sets)
- A M5 x 0.8 Tap (Can be substituted for whatever thread you decide for setscrew)
- Two Flathead screwdrivers for prying cover off
- An Angle Grinder with Grinding wheel
- A flat file (optionally w/ round file)
- a Drill & a drill bit set (we utilize sizes up to 1/4")
- An Impact with Philips driver (not required, but sometimes the cover screws are really tight and difficult to remove by hand or drill. An impact makes it significantly easier)
- A Vice large enough to hold the stator of the wheel (not strictly required, but will make your job a lot easier)
- A soldering Iron & Heatshrink
- Side cutters
- Channellocks, vice grips, or something else to grip motor shaft
- Blue threadlocker (243 was used to combat the possible issue posed by residual oil from drill & tapping and motor temps, but standard 242 is likely fine)
- 2 part epoxy or Silicone sealant. (I used JB Weld Plastic Bonder [50133] as I had it on hand)
- Black Sharpie
Step 1: Removing the Motor Cover
Time to get started.
We will begin by removing the cover of the motor. Sometimes the screws used to affix the cover are very tight, and may be difficult to remove by hand or even drill. If you have an impact available, it will make quick work of removing the screws. If you don't have one, just be sure to go slow, you don't want to strip these screw heads.
Once the screws are gone, we can use two flat head screwdrivers to pry the cover off. You need to be careful here. It is easy to have the screwdrivers slip into the motor and scratch or damage the motor windings. Go slow and apply even force.
Step 2: Pulling Out the Motor Stator
Now that we have the cover off, we can now remove the stator.
I find this to be easiest by placing the wheel between your feet and using channellocks to pull up by the shaft.
This will require a bit of force, as its being strongly pulled in by the permanent magnets around the bell.
Step 3: Removing the Wiring
To do the modifications, we need to remove the wiring. I do NOT recommend desoldering the wires, and instead I recommend cutting off the wires with just a little bit of insulation remaining on the connections. This will ensure that you resolder the wires to the correct place when it's time.
Step 4: Grinding the Shaft to Proper Dimensions
Time for sculpting the motor shaft.
Place the cover back onto the shaft, this will protect the stator from being damaged or covered in grinding dust.
Use some cloth to protect the motor stator from the vice. I used some shop towel here. be sure to not over tighten the vice, just snug enough to hold the motor.
The most important important thing to grind down is the flange/nub at the end of the shaft flush, as it will impede reassembly later on.
Secondly, we need to grind down the shaft a little bit to allow room for the wire. We need to bring the overall diameter to ~12.5 mm, but this isn't super critical. Being a little bit over will just make assembly a tigher fit. Be sure to try and not over grind beyond 12.5mm .
To try and keep your grinding as parallel as possible, I use a sharpie to recoat the surface after the first grind pass. Grind where there is still black, reapply sharpie, grind, sharpie, grind, so on and so on... until you bring the dimension down to 12.5mm .
After you finish grinding, I recommend you break all the corners with a file. This will prevent you from cutting yourself on the shaft, but more importantly prevent the motor wires from chafing on the sharp corners.
After grinding that side, we will flip the stator over and grind a small flat on the opposite side.
Step 5: Marking Up the Holes to Be Drilled
Now that the shaft is grinded, we can begin laying out where to place the new holes for wires, and setscrews.
Before we start, use something to plug the hole that the wires pass through on the inside. this will prevent debris from getting on the inside when we begin drilling and tapping. After plugging the hole, be sure to place the cover back onto the shaft for the remaining steps. In the pictures I forgot to do so and that meant I needed to do some post clean up that could've been avoided.
use the shaft of your trucks here for reference. I placed mine onto the motor shaft and made a mark about mid-way between the end of the rod and the beginning of the motor shaft fillet. The distance turned out to be about 38.2mm from the end.
After marking the hole to be drilled for the wire pass through, flip over the stator and make two marks for the holes for your setscrews. The placement isn't particularly critical here, just make sure there is enough room between them for the caps of the screws. If you have a center punch, use it to help prevent the bit from walking when we start to drill.
Step 6: Drilling Out the Holes
The hole for the wiring pass through will need to be drilled out to 1/4", but you of course shouldn't start with such a large size. Start from the smallest bit you have, and progress your way up through the sizes until you reach 1/4". Be sure to use oil, as this will prolong the life of your bits, but will also help capture all the debris from landing in the motor (if you forget to put the cover on like I had). After you reach 1/4", we will use the bit (while the bit is still inside the hole and spinning, of course) and slowly pull the drill down towards the shaft. This will create a slot for the wire to pass through. Make this slot about 14.4mm in length as pictured.
Make sure to run your file over the slot we just created as there will likely be a significant and sharp burr created that we must remove to prevent damage to the wire. Additionally, if you have a small round file, it is a good idea to try and break the sharp corners inside the slot to also prevent damage to the wires.
Now, after we've created our wire slot, and cleaned it up, we will flip over the stator and drill out our setscrew holes. The bit you should use will depend on what thread screw you decide to use, but in my case, since I had some M5 stainless screws laying around, I used a 4.2 mm drill bit. Consult Google for what drill bit size to use for the screw you want to use.
Step 7: Tapping the Shaft, Set Screw Holes, and Trucks
Now that we have the holes made, we can proceed with tapping.
I started with the setscrew holes, which I tapped to M5 x 0.8 . Be sure to use plenty of oil when tapping to make your life easier, and tap last.
After tapping both holes, I flipped the stator upright, and prepared to tap the motor shaft for the trucks. The standard thread of stateboard/longboard trucks are 5/16"-24 TPI , so be sure to use the correct tap, or you will be very sad later on. I made sure to thoroughly oil the tap, and went very slow. Check from multiple angles that you are tapping the shaft as straight as possible and follow the proper tapping etiquette (plenty of oil, go slow, 2 turns forward & half turn back, and back tap out often to clean out chips from flutes and reapply oil) .
Be sure not to tap the motor shaft too deep, as the threads will make wiring difficult to pass through later on. See the Pictures to see about how far to tap the hole from the view of the slot.
After the shaft is tapped, we need to tap both shafts of the trucks to make them fully threaded. This is done easily with the 5/16"-24 TPI die. Again, be sure to apply oil.
After everything is threaded, you need to be sure to clean all the chips and oil from the parts. The trucks are easy to clean, but the motor shaft may be a bit tricker. After removing the paper plug from the motor, I used a combination of compressed air, Acetone, and cotton swabs to remove chips and oil. Remove as much stray metal chips as you can, and try to remove oil as best as you can. it is especially important to thoroughly clean oil out if you opt for the non-oil tolerant threadlocker.
Step 8: Rewiring the Motor
It's time to add the wiring back to the motor.
While you reuse the original wiring from the motor, I opted to use another wire which features the phase wires & hall-effect wires all in a single connector, which is also IP-65 rated. I found this connector after much searching trying to find a nice compact connector that can handle the high motor power, sensor wires, and be decently water resistant. The connector is a HiGo Z910, which appears to be utilized in low-medium power ebikes. Thankfully, Bafang has adopted this connector as the standard for their bike parts, which means we can find inexpensive extension cables on the internet (Wohoo!). You can find extension cables or 60-160cm length easily by searching for "9-pin ebike extension" on Amazon or Ebay.
I use a 60cm extension cable and cut it on half. I used the male-pin side for the motor, and the female socket for the ESC-side.
I stripped a fairly long 4.5" of insulation off which may seem overly long, but it really will make wiring and feeding through much easier if you cut longer than needed and cut it back after the fact.
Getting all the wires in can be very tricky, but I found that if you push all the hall sensor cables through first, then individually feed each thick phase wire in, you can get through it fairly easily without many hassles.
After all the wires are in, push the cable through until the black insulation just peaks through on the inside of the motor hole as depicted in the pictures.
Start with the thick phase wires first by desoldering the excess wire we left behind from the first winding, and strip the new wire and solder it to the phase wire (make sure to place the heat shrink on first, and make sure it's a good solder joint) . Do this to each of the three phase wires, and gently press them out of the way into the gap of the stator.
With all of the Phase wires done, proceed with the same steps on the sensor wires. With the 9-pin cable I opted to use, you will notice an unused white wire. In ebikes, this is usually used as an extra speed sensor, or as an internal temperature sensor. You can optionally cut it off or bundle it up like I did. Leaving the wire behind will allow me the option to come back later and add a temperature sensor if I desire.
After Soldering everything up, use a small zip-tie to gently affix the wires to the core. This will prevent them from moving or vibrating later on.
Now that everything is in place, use epoxy or a silicone sealant to cover the bundle of wires, and most importantly, try to get as much into the wire hole as possible to try and prevent dust and water ingress from the port. Do the same with the exit hole.
As you will see in the pictures, I opted to 'paint' the grinded parts of the motor shaft with sharpie just because I thought it looked better. I doubt it provides any rust prevention, but I'm not particularly worried about that as I store my longboard in a dry area anyways.
Be sure to allow the epoxy or silicone to set before moving it or proceeding to the next step.
Step 9: Reinstalling the Cover
Now that our epoxy has set, we can proceed to the next step.
Before placing the cover back on, I opted to remove the rubber seal, so that I could re-grease it. This isn't necessary, but all the motors I have opened have little to no grease on this seal, which reduces it's lifespan and potential for preventing dust and water ingress. I recommend re-greasing this part, but it's up to you.
I removed the seal by pressing behind it gently with a flat head, where it popped out. I greased the seal and the part it rides on the shaft with super lube synthetic grease. Whichever grease you decide to use, make sure it is rubber-safe before applying it, otherwise you may cause more damage than good.
I pressed the cover back on the shaft w/ wire passing through it. It's likely to be a tight fit, but just be gentle and massage it to allow it to pass over and seat at the bottom. After getting the cover on, I greased the seal area of the shaft, and slid the seal over the shaft and pressed it back into the cover.
Step 10: Mounting the Motor to Trucks
We are nearing completion, just a little bit to go.
With the cover back on, it's time to install the motor to the trucks.
This is done easiest by placing the trucks in the vice.
Apply plenty of threadlocker to the truck shaft, and begin threading the motor on. It may get tough to thread towards the end, so feel free to use channel locks to get more leverage to tighten it. You want to keep going until the motor shaft is flush with the end of the trucks.
After screwing the the motor in, it's time to do the same to the setscrews. Apply a little thread locker to each, and screw them in. Make sure they are snug, but don't try to strip them out, of course.
Step 11: Finishing Up & Reinstalling Wheel
Now that the stator is properly mounted to the trucks, we can now install the wheel/bell back on.
Grab the trucks, and place the the wheel on the floor. Grip the wheel with your feet and slowly lower the stator in. It will pull in fast, so be careful to not let go of the wheel with your feet. Once the stator is in, align the countersunk holes on the cover with the threaded holes in the bell. Once aligned, gently press down evenly on the cover, and it will snap down.
We can now screw the cover back on. Make sure to go slow and tighten in a 'star' pattern. Don't over tighten the screws or you risk stripping the thread or the screw head off.
Once screwed together, I recommend placing a zip tie around the shaft and wire between the setscrews. This will provide more mechanical protection from the wire being tugged out, and potentially compromising the epoxy/sillicone seal.
Congratulations! you have successfully mounted a hoverboard wheel to longboard trucks! This solution is extremely robust, and I have personally been riding with this solution for several months now up hills, through the rain, in mud and gravel, with no issues.
